SAWDUST-SALT MSXTURES TO DRY AND
TO STORE SHELLED CORN

Thesis for the Degree of M. S.
MECHiGAN STATE UNIVERSITY
Antonio M. Chavos
1962

id

LIBRARY

Michigan State
University

 

SAWDUST — SALT MIXTURES TO
DRY AND TO STU-US SI'IELIED CORN

by
Antonio ll. Chaves

AN ABSTRACT

Submitted to the College of Agriculture
Michigan State University of Agriculture and
Applied Science in partial fulfillment of

the requirements for the degree 0!

MASTER OF SCIENCE

Department of Far- Crops
1962

APPROVED

 

Antonio M. Chaves

ABSTRACT

A dry mixture of sawdust impregnated with about 10% by
weight of NaCl (or CaCle'), when mixed with datp' shelled
corn absorbed moisture rapidly, converting the dry salt to
a saturated solution which was absorbed by the sawdust.
The corn dried until the vapor pressure of the air between
the kernels approached that of the salt solution. For
drying to the equilibriun.relative humidity of a saturated
salt solution, namely 755 a. H. (or about lhfi Ioisture in
the grain), such a sawdust - salt nixture absorbed water
to about 30$ of its original dry weight. lust of the
drying occurred in the first day or two.

The sawdust —' salt can be readily removed fro- the
grain if it is originally screened in a suitable tanner.

The mixture, and particularly its-sawdust conponent,
was a powerful insecticide and repellent for granary
weevils (SitOphylus granarius). Such a nixturvot salt
and an absorbent (sawdust) provides an inexpensive means
of drying grain and avoiding infestation by granary

weevils.

SAWDUS‘!‘ - SALT MIXTURES TO
DRY AND TO sroas SHELLED CORN

by
Antonio I. Chaves .

A THESIS

Submitted to the College of Agriculture
Michigan State University of Agriculture and
Applied Science in partial fulfillment of
the requirements for the degree of.

MASTER OF SCIENCE

Department of Far- CrOps
1962

ACKNOWLEDGMENT

The author wishes to express his appreciation to
several people for their noteworthy contributions to this
thesis. Those directly responsible for the production of
this work through their efforts are as follows:

To Dr. S. T. Dexter of Farm Crops Department as his
major professor and advisor, he expresses his deepest
gratitude. Dr. Dexter contributed innumerable hours of
technical assistance, aid in experimentation, and patient
devotion in the production of the manuscript.

To Dr. C. W. Hall of Agricultural Engineering Depart—
ment for his interest and suggestions throughout the

production of this work.
Grateful appreciation is also extended to all those

who provided encouragement and that undefineable something
without which this whole endeavor would have been a

complete failure.

DEDICATED
TO

MY MOTHER, VIRGINIA, WHO ENCOURAGED ME
AS A BOY

AND TO

HY FIANCE LUCIA MARIA, WHO INSPIRED ME
AS A MAN.

TABLE OF CONTENTS

LIST 0F TABLES . . . . . . . . . . . . . . .

LIST OF FIGURES . .

' IMOWCTI ON 0 O O O 0 O O O O O C O O O O O 0 0
LITERATURE REVIEW

A.
I.

II.

II.

III.
IV.
V.

BRAZIL

Its Geography and Climate, Population,
Agriculture, and Its Power . . . . . .

The Justification of the Author for
This Thesis . . . . . . . . . . . . . .

GENERAL PRINCIPLES OF GRAIN STORAGE
Grain Storage - General Considerations.
Moisture Migration and Mbisture

Accumlation.....
Mbld Growth . . . . . . . . . . . .
Insect Activity . . . . . . . . . .
Drying of Grain . . . . , . . . . . .

MATERIALS AND METHODS

I.

II.
III.
RESULTS

Shelled Corn, Drying Agents, and Insects
used 0 e a o e o e e O O 0 O o a e e 0

Preparation of ”DRIERS" . . .
Preparation of "MIX" . . . . . . .

Preliminary Experiments

DRIER Na5, DRIER - Nalo, and DRIER -
N320 a e a e e e e 0 ~ 0 e e o o e o e

DRIER CaS, DRIER - 0810, and DRIER -
c320 e e e e e o e a e e e e e e e e e

Page
iii

13

18

23
27
29
35

57
67
69

76

76

II.

DRIER - S .
Experiments with DRIER - Nalo, DRIER -

11

0810, and DRIER " s 0

III.

IV.
N310

V.

DISCUSSION OF THE THEORY OF DRYING SHELLED CORN
USING A MIXTURE OF SANDUST AND SALT (DRIER)

SUMMARY AND CONCLUSIONS

1.

sawdust mixture .

II.

LITERATURE CITED

0

Experiements with Granary Weevil

O

The Insecticidal Effect of the DRIER
(mixture of salt and sawdust) on
Granary Weevil .

SUGGESTIONS FOR FURTHER STUDY

Experiments with DRIER - NalO, DRIER -
Oslo, and DRIER - 8 under special
conditions

Experiments in large scale with DRIER -

Drying shelled corn by using a salt -

Page
78

88

98

106

112

115

116
117

Table

10.

11.

12.

111

LIST OF TABLES

Weather Data From.Brazil . . . . .
Electrical Power: Installed Capacity . .
Brazilian Farm.Cr0ps Production 1960 . . .
The Most Productive States of Brazil . . .

Maximum.Mbisture Content For Safe Storage
and Corresponding Relative Humidities for
Specified Kinds of Grain and Seeds . . . .

Reproduction of Rice and Granary Heevils
(50 pairs each) in Wheat as Affected by
Temperature and Grain Moisture, Indicated
by Number of Progeny After Five Mbnths . .

Shelled Corn Equilibrium.flbisture Content
(wet has 18 ) O O O O 0 O O O O O O O O O 0

Water Taken.up b Blocks of Three Species
of Wood Impregna ed in the Dow Flake
Solutions of various Concentrations . . .

Quantities of the Principal Plant nutrients
Contained in Various Plant Products, per

.ton of dry matter . . . . . . . . . . . .

vapor Pressure and Relative Humidity of
Saturated Aqueous Sodium.Chloride Solutions
and Preparation of Saturated Salt Solutions

vapor Pressure and Relative Humidity of
Saturated Aqueous Calcium Chloride
Solutions . . . . . . . . . . . . . . . .

The Drying of Shelled Corn (3075 M.C.W.B.)
When Conditioned in Sealed Containers at
80°F. with: MIX - 3 Na5; MIX - 5 was;
MIX-10139.5; m13m10;m-5m10;
MIX - 10 Halo; MEX - 3 Na20; MIX - 5 Na20;
and MIX 10 Na20 . . . . . . . . . . . . .

Page

12
16
17.

22

3h

39

1&8

57

64

66

Table
12A.

12B.

13.

13A.

13B.

1“.

15.

l6.

17.

18.

iv
Page

The Drying of Shelled Corn (305 HgC.W.B.)

When Conditioned in Sealed Containers at

80°F. with: MIX - 3 Gas; nix — 5 Gas;

NIX - 10 Ca5; MIX - 3 08.10; NIX - 5 08.10;

MIX - 10 0310; MIX - 3 Ca20; NIX - 5 0820;

MIX — 10 Ca20 . . . . . . . . . . . . . . 80

The Drying of Shelled Corn (30% MiC.W.B.)
When Conditioned in Sealed Containers at
80°§.with:m-BS;MIx-SS;HD{- 8
10 0.0.0.0.... 0000000 1

The Drying of Shelled Corn 1120* n.c.w.s.)
in Sealed Containers at 80° . with: MIX -
l Na10;MIX - 3 Na10;NIX - 5 Na10;MIX -
8NalO;andMIX-10Nalo......... 83

The Drying of Shelled Corn (205% M.C.W.B.)

in Sealed Containers when Conditioned at

80°F. with: MIX - 1 Cam; MIX - 3 Oslo;
uni-50am; MIX-80am; andMIX-lo

Calo . . . . . . . . . . . . . . . . . . . 85

The Drying of Shelled Corn (20% 14.0 .W.B.)
in Sealed Containers when Conditioned at
80°F.w1th: MIX-133NIX-333HIX-
SS;NIX-88;andMIX-lOS...... 87

The Drying of Shelled Corn (20% M.C.W.B.)

in Sealed Containers when Conditioned at

80°F. with: MIX - 3 Halo (a); MIX - 3

Halo (b); MIX - 3 Oslo (a); and MIX - 3 S (a). 89

The Drying of Shelled Corn (22.5% M.C.W.B.)

in Bins (as designated) when Conditioned

with MIX - 3 Halo (using "rock salt " as

sodium chloride in DRIER mm) and under

a Great variation of Temperatures . . . . . 96

Behavior of Granary Weevil When in Mixture -
With MIXES e e e e e e e o e o e e e e e e 98

The Theoretical Uptake of Water from Damp

Shelled Corn (100 grams) kept in sealed

containers at 80°F; with designated MIXES,

assuming an endpoint at 75% R.H. . . . . . 108

Uptake of Water From 100 Grams of Shelled

Corn at 2 M;C.W.B. Kept in Sealed Contain-

ers at 80 . during 10 Days with th

Designated MIXES . . . . . . . . . . . . . 110

Figure

BA.

BB.

10.

11A.

113.

110.

V

LIST OF FIGURES

Map of Brazil (showing the region of grain
production) . . . . . . . . . . . . . . . .

Nap of Brazil Average Annual Temperature
(maximum) . . . . . . . . . . . . . . . . .

Map of Brazil Average Annual Temperature
("1111”) a e o e e e e. e e e e e e o e e 0

lap of Brazil

Annual Average Temperature.

Convection Air Currents With Warm.Grain in
Bin With Colder Surrounding Air . . .

Convection Air Currents With Cold Grain in
Bin With Warmer Surrounding Air . . . . . .

The Heisture Content in the Tap Six Inches
of a Bin (variation From July to December).

Effect of Temperature on Hold Activity in
Shelled Corn at 16% Mbisture Content . . .

Desorption Isotherms for Sawdust . . . . .

The Curves Show the Saturated vapor Pressure
of Water and of a Saturated Solution of

NaCl Over the Temperature Range of 0 to 50°C.

and Also the Ratios of the Two Intervals. .

vapor Pressure in Corn, As a Function of Its
Moisture Content for Various Grain Tempera-
tures, and in the Air, As a Function of Its
Relative Humidity at various Temperatures -

c. O O O O O O O O O O O O O O O C O O O

Weighing Shelled Corn and Showing the
Equipment Deed During the Laboratory
Experiments . . . . . . . . . . . . .

Dr. S. T. Dexter and the Author With the
Materials Used in the Large Scale Experi-
ments (Corn in Bags, Salt, and Sawdust) . .

Shoveling Sawdust With Salt Solution 1
Preparing the DRIER . . . . . . . . . . . .

Page

24

2h

26

28
61

62

63

7h

71;

7h

Figure

11D.
11E 0

_12.

13A.

13B.
130.

In.

15A.

153.
150.
15D.
153.

15F.

15G.
15H.

16.

vi

Filling the Bin With the MIX - 3 NalO . . .

Screening to Remove the Sawdust Before
WeighingtheDryCorn......... .

Moisture Content of Wet Shelled Corn
When Stored With MIX - 3 8, MIX - 3 Nalo,
mam-30310 eeeeeeeeeeee

Relative valumes of DRIER Halo to damp corn
Weight and volume of MIX 3 Nalo . . . . . .

The Author ShOwing to Dr. C. W. Hall (his
Minor Professor) the Experiments with the
Granary Weevils in MIXTURE with DRIERS .

Moisture Content of Wet Shelled Corn When
Stored in Opened Bin, Sealed Bin, and in a
Bin With a" Layer of Sawdust-Salt on the
Top, Mixed with Sawdust and Sodium Chloride.

Movement of G. Weevil in "DRIER" Co
Environment . . . . . . . . . . . . . .

Mbvement of G. Weevil in ?DRIER" Environment
Behavior of G. Weevil in Contact With DRIER
Behavior of G. Weevil in Contact With Corn.

Behavior of a. Weevil in Mixture With DRIER
and Corn .,. . . . . .

Movement of G. Weevil in Mixture With DR
md com o a e 'e e e e e e e e . e e e e e

Mbvement of G- Weevil in "DRIER" . .

Movement of G. Weevil in "DRIER" Corn
Environment . . . . . . . . . . . . . . . .

Behavior of Granary Weevil in Sawdust - Corn
Environment When A Source of Air is
supplied 0 e e o o e e e e e a e e e e e e

Page

75

75

90

95
95

95

97-

101
101
102
102

103

103
104

104

105

INTRODUCTION
* Antonio M. Chaves

Techniques for drying and storing grain depend to a
considerable degree upon the culture, degree of mechaniza-
tion and urbanization, etc. of the country involved, Where
hard surfaced truck roads pass every farm and railroads
are available near at hand, drying and storage of grain
may be economically performed in large central establish-
ments. In Brazil a large proportion of the population
inhabits small or middle-sized farms, where the products
that are grown are consumed, except when hauled on donkey-
back or on wagons hauled by horses and oxen to villages or
cities, on paths or roads not designated for heavy traffic.

To document this situation more fully, the first part
of this paper is related to Brazil, in the context of
storage and the losses of small grain and shelled corn. In
brief, the subtropical temperatures and high relative
humidity of the air in the grain-producing regions of
Brazil give rise to profound problems due to molding and
insect invasion in stored grain. The experimental work.
reported in this thesis outlines a method of drying and
storing grain that might be feasible for small farmers in
Brazil and the many other subtropical or tropical countries
with similar problems.

 

‘ Bachelor Science in General Agriculture, graduated
from the U.R.E.M.G. in 1958, and an AID fellowship holder
from Brazil, on a project relating to training in grain
storage.

A . BRAZIL .
I. ITS GEOGRAPHY AND CLIMATE, POPULATION. AGRICULTURE,AND
ITS—POWER

 

Geography and Climate - Brazil's area of 3,287,195
square miles resembles roughly the shape of an equilateral
triangle. The north-south and east-west dimensions of
Brazil at the points of their greatest extent are almost
identical - 2,68h and 2,680 miles respectively. The
farthest reaches of the country extend from latitude
h°20'h5" N. to latitude 33°A5'09" S. and from longitude
3h°h5'5h" W. to longitude to 73°59'30" W., covering 38
degrees of latitude and 39 degrees of longitude. Most of
Brazil is situated to the east of the United States, for
all of its territory lies east of the longitude of New
Ybrk City.

Brazil's neighbors include all the countries of South
America except Chile and Ecuador. 1 '

Fifty-seven percent of Brazil is made up of highlands,
varying from 650 to 3,000 feet in altitude, in which
irregular mountain ranges form high plateaus. The remain-
ing forty-three percent of the land is less than about
650 feet above sea level.

iMost of the territory of Brazil lies within the torrid
zone. Since the tropic of Capricorn passes through the
city of Sao Paulo, only the area to the south, including

parts of the states of Santa Catarina and Rio Grande do
-2-

-3-

Sul, are in the temperate zone.

Practically all of Brazil lies south of the Equator,
and the seasons are the reverse of those in the United
States. The farther to the south, the more pronounced are
the seasonal changes. The Amazon area is rainy and humid,
with high average temperatures the year round. The heat
in the coastal regions within the torrid zone is tempered-
by the trade winds and by the proximity of the ocean, and
stiff breezes are characteristic of the coastal cities of
the Northeast. In the highland areas of the interior, the
altitude somewhat offsets the effects of low latitude.

Frost occurs with some frequency in the three southern-
most states. The northern limit of the frost line is in
northern Parana and the extreme south of Sao Paulo.

There are three main types of climate in Brazil, each
of which is subdivided: (l) Equatorial or tropical
climate, (2) Subtropical, and (3) Temperate. (Figures
1, 2, 3, and h)

(l) Equatorial climate. This is characterized by a
mean temperature of 26° to 27°C. The area occupied is:
Amazonas, Para, Maranhao, Piaui, Ceara, Rio Grande do Norte,
Pernambuco, Alagoas, Goiaz, Mato Grosso, and Bahia. It is
sub-divided into super humid, continental humid, and semi
arid.

(2) Subtropical climate. Average annual temperature
varies between 230 and 26°C. This includes Sergipe, part

 

 

 

 

 

 

 

 

 

 

 

 

 

 

' r l r
.4: 72° 44° 40° 3%;
ATLANTIC OCEAN
on EOUATOR o.
_ 4, AMAZONAS PA RA 44
MARANHAO
.
IRONDONIA.
i|2° WIAl‘O snosso
r16.
BRAZIL-
SCALE
STATUTE MILES
Mir—250°
KILOMETERS
-2”.
~28.
7.69 7?’ 6.8“ 63°

  

 

 

 

 

 

 

 

 

 

FIG.|.— MAP OF BRAZIL'- (4).

(SHADED AREA= REGION OF seam PRODUCTION) ’

FIG.2- AVERAGE ANNUAL TEMPERATURE-(4),
(MAXIMUM)

Ili-

ll"

 
   

  

 

 

a. ‘

ll mull
.Hlll

    
  

 

 

e.'...

.t-.- In...

 

.
O '0‘

 
 
  
  

   

 
 
   
  

'o'o-
e'.

0.0,.
e' "
e-

 

’Ilm
.‘aéiill'til't'

a." '

 

 

 
 
  

 

  
 

 
 

119““ "ii:

1.:.:.: .0
'4'.
and .‘l""
’ I

L. .2;

 

 
 
 
  

HI .- .-‘Z'.'

. I
.’0‘ .
a 0 A "

    
  

ae‘

  

O.
y-
a...

' a

.—
.—
—
-
“v

 

‘0
.0

 

Jill

'-‘.:-..' -‘ ”W”

- IS TO 26°c.-64.4 T0 78.8’E'

- -: 2::2-«5'26’Tozsoc. 73s TD 32.4%:

 

 

- - 28T030°C-82.4T0 86°F

 

FIG: 3 -AVERAGE ANNUAL TEMPERATURE-(4)_
(MINIMUM)

    

-<IOTO|I°G.-<50TO5I.8°F -

 

I7T0I9°o— ezsro 66.2%”

I9 T02I°C.—66.2 TO 69.8%?

 

FIG.4' ANNUAL AVERAGE TEMPERATURE'(4)

    

-l6 TO 20°c.- 608 TO 68°F

31‘: 22° 0, _ 7|.6°F

Eerie — 75.6°F

 

TABLE 1
Weather Data From Brazil

Relative Humidity Percentage (Monthly Average) in
the Main Grain Producing States (3)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

MONTHS i *MOI-7368‘~F‘S;~igin. _SC ifRGS—TGOIAS
January 72 73 81 82 88 7a 8a
Egbruary 62 76 83 8a 78 76 78
Lurch 75 i 79 86 82 79 75 83
[April 63 73 78 88 80 82 7o

3' 59 76 81 8h 80 86 65
June 60 70 73 80 82 86 65
July 5a 71_ 68 7a 88 81 56
August 52 . 75 75 72 81 82 54
September 56 76 78 79 82 81 #9
October 62 76 I 77 75 79 ’ 76 65
November 7h 75 80 80 80 68 79
December 61 7h ' 81 78 83 71 77

* MG - Minas Gerais GB - Guanabara

Sao Paulo PAR - Parana
Santa Catarina RGS - Rio Grande do Sul
Goias

SP
SC
00

-9-

of Goiaz, ESpirito Santo, Rio de Janeiro, and Minas Gerais,
almost the whole of Mato Grosso and part of Sao Paulo. It
comprises two types, two subdivisions: maritime, semi-
humid and continental semi—humid .

(3) Temperate climate. Its characteristics are that
of the coldest month of the year, where the medium.tempera-
ture is equal or less than 18°C.

One-fifth of the total area of Brazil is included in
the third climate, about half of the state of Minas Gerais,
50% of the state of Sao Paulo, the whole of Parana, Santa
Catarina, and Rio Grande do Sul, part of Mato Grosso. It
is subdivided into three types: super-humid on the coast,
semi-humid in the interior, and semi-humid in the heights.

To illustrate these, see Figures II, III, and Iv
where the author shows the map of Brazil with special
attention to the most productive states as far as produc—
tion of rice, corn, black beans, and wheat are concerned.
(See also Table 1)

Population - The population of Brazil, according to
data from the census of 1960, was 70,527,621; an increase
of 36 % over the 51,976,357 recorded in the census of 1950.
One half of this pOpulation lives in the rural area.

Agriculture - Agriculture continues to be the main-
stay of the Brazilian economy, although the rate of
agricultural expansion has lagged behind the industrial

growth in recent years. Agriculture and industry each

-10-

contributed 26% of the national income in 1959. Neverthe-
less, in 1962 our statistics indicated the share of agricul-
ture as 26 percent, against 27 percent for industry.
Hawever, 58 percent of the labor force was engaged in
agriculture, according to the census of 1950, in addition
to 2 percent of the labor force occupied in forestry and
fishing. The importance of agricultural products in
general, and coffee in particular, in the export sector is
predominant, due to the fact that Brazilian farmers have
price support program for coffee but not for cereal grains
and the rest of our crops and livestock. (25)

Crops, both annual and perennial, accounted in 1959
for 65 percent of the total value of agricultural produc-
tion, livestock and animal products about 29 percent, and
extractive forest products for about 6 percent. (3) Data
in the production of cereal grains and its value are shown
in Table 3.

Brazil has a large potential for expanding agricul-
tural production. The development of agriculture has been
hindered principally by the inadequacy of transportation
facilities, lack of storage facilities and rural electrifi—
cation, insufficient capital and credit availiabilities,
deficiencies in the marketing system, the small number of
agronomists, the lack of agricultural engineers, and
outdated agricultural methods. Only a small proportion of
the country's area, representing 2.3 percent of the land

-11-

area in 1950, is under cultivation. No reliable estimate
has been made of the extent of arable land in Brazil.

The basic reason for the lag in agricultural produc-
tion as calpared with the growth of industrial production;
however, is widely considered to be the inadequacy of the
transportation system. The cost of moving crops to market
is a basic factor in determing whether capital and labor
can be profitably employed in crop production in a given
area. The improvement of the road network within the past
few years has increased agricultural production in Goias
and other frontier areas, and consequently, the loss of
cereal grains and other agricultural products due to the
lack of storage facilities has also been increased.

M - To meet the needs arising from the country's
rapid economic deve10pment, the expansion of the power
generating capacity is one of the maJor tasks of the
Braz ilian government. A ten-year program of around
5,000,000 kw of additional capacity is under way and it
aims to raise Brazil's generating capacity from about
3,100,000 kw in 1955 to over 8,000,000 kw in 1965, and
about 13,000,000 kw by 1970 See Table 2. (25)

Electric energy produced by the principal power
°%anies in the first quarter of 1959 (2, 3) was distrib-

uted, by classes of consumers, as followsfin percent:

-12-

industrial,40; residential, 20; commercial, 15; and others
(including block power sales to electric traction companies
and Federal and state government power consumers as well

as sales for public lighting 1.25.) (25)

TABLE 2

Electrical Power: Installed Capacity
(in 1,000 kw) (25)

 

 

 

 

 

 

 

.YEARS HYDRO THERMAL TOTAL
1940 1009 235 1254
1950 1536 347 1883
1955 2481 667 3148
1960 3262 801 u063

[1065 (Est) 7300 1320 8620

 

 

 

 

 

II. THE JUSTIFICATION OF THE AUTHOR FOR THIS THESIS

Unfortunately I do not have “enough“data fro-Brazil on
the number of storage facilities we have and how many we
need in order to overcome this problem which has been well
known from generation to generation; but so far it remains
the same as in some decades ago. However, I have been in
different states of grain production in my country working
for Escritorio Tecnico de Agricultura (Brazil and United
States) and have received from our farmers requests such
as: can't you give me good plans to build a corn crib, a
bin, a bulk storage, etc., in order to keep my grain well-
stored and safely?

At that time (1959 to 1961) I could not help them
because I did not have sufficient background to solve such
problems. But, now with the knowledge that I have acquired
from specialists in grain storage belonging to the depart-
ment of Farm.Crops and Agricultural Engineering of Michigan
State University, I hope that I will be able to overcome
at least part of this tremendous problem.by using a mixture

of sawdust and salt to dry and store shelled corn. When
corn is dried with this mdxture, it is not necessary to

 

have electricity while the materials sawdust and salt are
both readily available and inexpensive. The mixture of

sawdust and salt may be used in the regions which are under

the following conditions:
-13-

-1h-

1) Corn and other food grains are grown on all farms
in Brazil, especially on small ones where they are used for
home consumption.

2) Transportation to and fromimarket is expensive and
unnecessary for the above reason.

3) When farma get larger and farm populations smaller,
when electricity and good roads become universally avail-
able, then other mechanical means of drying and storage
may be more practicable, and even less expensive than the
use of the mixture sawdust and salt.

Any country, in order to survive, needs food, and
therefore, food storage. This immediately poses two
questions:

(1) Is it possible to improve the conditions of
living of a people without having storage facilities and
transportation?

(2) Is it worthwhile to increase the agricultural
production without having a place to keep such production
safely?

The answers for both questions are positively N0.
Nevertheless, in my country we are Dmproving our transpor-
tation, we are increasing our production, and the problem
as concerns storage facilities still remains the same).

With respect to the national grain situation, we (1)

have:

-15-

8) Brazil will continue to suffer heavy and unneces-
sary losses of agricultural production; and on an ascending
scale as production increases, until there is implementa-
tion of a national construction program designed to satisfy
the major requirements for storage facilities. A national
approach appears Justified by the magnitude of the probable
investment; However, it might be limited to the provision
of credit and technical aid to local entities both public
and private, or cooperatives, as the case may be.

b) The need for more grain storage capacity through-
out the country is obviously so great that well-designed
impending projects, particularly thOse of commercial and
farmers' interests, need not be discouraged or postponed.

c) With respect to individual projects, there is the
need for considerably more engineering preparation
supported by precise economic data based upon production
trends, marketing potential, and research data for our
condition due to the fact that grain storage is a regional -
problem. i

d) Brazilian farmers need price support for cereal
grains and corn.

e) Brazilian farmers need production credit on
reasonable terms.

f) Brazilian farmers need more technical aid, but in
order to solve that problem*we need to have more special-

ists in grain storage.

-16-

The following is an example of losses in corn, wheat,

rice and bean storage in Brazil.

TABLE 3
Brazilian Farm Crops Production 1960 (3)

 

 

 

 

 

 

 

 

 

 

 

 

 

.mszézziian ”“8232.“- L...Y2:3:.....J
mice u,865 2,926,000 44,278.0 _- W
Corn 7,248 6,580,000 41,059.0
[Black Beans 1,676 2,357,143 I; 25,245.0
Fiheat 300 1 , 159, 888_ 11 ,583 .8
[TOTAL 14 .089 13 ,023,028 ' 122 , 165.8

TOTAL PRODUCTION 14,089,000 Tons
TOTAL LOSSES 25% from an annual harvest

(this figure is estimated
by the author)

This example may be summarized as follows:
(1) Losses due to lack of drying facilities . . . 7%

(2) Losses resulting from weather to grain
stored in Open or partially covered shelter . 5%

(3) Losses from insects and rodents to faulty
storage methods and due to infestation in

thefield..... . ......lO%

9
(4) Losses due to improper handling and
transportation in sacks . . . . . . . . 3%

-17-

A.25$ loss from.an annual harvest of 14,089,000 tons

means a loss of 3,522,250 tons valued at 30,541.45 millions

of cruzeiros.

The following table shows the most productive states

of Brazil by crop.

The most productive states of Brazil are:

(See Figure 1)
TABLE 4

 

{a

(1958) (3)

 

 

 

 

 

 

 

 

 

 

 

 

.1. -fl- in- I -. __ _.

STATES RICE CORN [BLACK BEANS WHEAT
(tons) (tons) (tons) (tons)

M. aerais 728,763 1,660,200 331,489 ------

Goias 412,286 258,832 66,188 ------

Sao Paulo 833,323 1,404,435 201,u02 ------

Parana 210,110 1,153,222 304,197 77,529

S. Catarina 134,132 5h8,287 70,160 96,915

a. a. Sul ‘805,035 1.u83.775 139.19u ”07,308

 

The author believes that the data presented justifies

the expense in time and money which were necessary to

increase his knowledge of grain storage in order to

contribute to improvement in this area.

 

B) GENERAL PRINCIPLES OF GRAIN STORAGE
I) GRAIN STORAGE - GENERAL CONSIDERATION

For anyone who wants to invest money in storage of
small grains and shelled corn it is desirable to be or to
become acquainted with certain requirements as follows:

(1) Need of temporary or permanent storage.

(2) Data available of temperature and relative
humidity .

(3) Kind of grain to be stored.

(4) Market price. _

(5) TranSportation facilities.

(6) Construction.material available.

(7) Enough production to compensate a great invest-
ment.

After fulfilling all preliminary requirements above,
one should know other requirements such as:

(1) Condition of grain.

(2) The function of the grain.8torage in order to
maintain the condition of grain. '

(3) The structural requirements of the buildings.

Any of the above requirements should be followed
carefully. It is not necessary to say which requirement
is more important than the other, because the main objec-

tive is to keep the grain safely and to maintain its

quality. (2)
-18-

-19-

The seven first requirements are not difficult to
meet because, roughly speaking, they depend on economic
and weather data.

The other three are most important and it seems
desireable to summarize them before considering drying

agents.

Conditions of Grain for Safe Storage

The principal factors in safe storage are moisture
content and temperature. This has been proved in the
united States and other countries by many years of experi—
ence and research on the storage of grain. Foreign
material and cracked grain can also be factors if they
occur in excessive amounts.

The maximal moisture content at which grain can be
stored safely depends on the kind of grain, the locality
in which it is stored, the methods of conditioning, and
the length of the storage period. Wheat may be stored
safely for a year with moisture content of about 1% higher
in North Dakota than in Kansas, because the mean air
temperature in North Dakota is about 10°F. lower during
the summer. (2) (See Table 5)

The moisture content of grain is also an important
factor in the activity of insects. Where it is as low as
9% in shelled corn and wheat, most of the destructive
insects become inactive. (2) (See Table 6) Nevertheless,

-20-

such low moisture content is not easily obtainable in
current practice. It is well known that grain can absorb
moisture from or give up moisture to the air surrounding it.
When the grain neither loses nor gains moisture, it is
considered to be at its "Equilibrium.loisture Content," for
the temperature and relative humidity surrounding the
grain. Some information on equilibrium.mo1sture content

is given on Table 5.

The second factor in conditioning for safe storage is
temperature. It is already proved that, to some degree low
temperature off-sets the effects of high moisture with
respect to the hazards of mold growth and insect develop-
ment. For this reason, in colder weather the grain can be
kept safely with a moisture content of l to 1.5% higher
than in warmer weather. For example, in northern United
States, grain moisture content may be 1 to 1.5% higher
than in southern United States. (See Table 5) Today, in
order to compensate for this advantage it is ad§isable to
use aeration (cooling grain) in localities with.warmer
climates. (2)

Functions of Storage Buildings

B. M. Stahl (25) has stated comprehensively the
functional requirements for a good storage as follows:

The storage should help to:

1. Keep the grain safe from:

-21-

Damage due to moisture

Damage due to heat

Damage by insects

Loss in quality

Objectionable odors and materials

2. Provide Job safety and convenience when:

b.

c.

Moving grain (to, into, out of, and
from the storage)

Inspecting the grain

Servicing the grain and storage

C. W. Hall (12) lists the functions as follows:

1. The basic requirements of bins for grain are:

8..

There should be no Openings or cracks
permitting loss of product.

Rain, snow, and soil moisture must be
excluded.

Reasonable protection.must be provided
against thieves, rodents, birds, poultry,
insects, and obJectionable odors.
Facilities mst be permitted for
effective fumigation to control insects.
Reasonable safety must be provided from

fire and wind damage.

The structural requirements of the building:

1. Special attention should be given to: (2h)

Foundations

-22-

b. Anchoring

c. Floors
d. Walls

e. Roofs

f. Openings, ducts and closures

TABLE 5

Maxim moisture content for safe storage and corresponding
relative humidities for specified kinds of grain and seeds.

(11)

 

Kinds of grain and seed

Maxim moisture
content for safe
storage ( ercent
wet basis?

Relative humid-
ity of air at
which grain is
in equal ibrium
with air (77°F.)
(percent R.H.)

 

 

Shelled corn, oats
Wheat hard red winter
Wheat soft red winter
Wheat hard red spring
Soy beans

Rice

Pea beans

Grain sorghum

 

A 13.0

A 13.0 - 13.5
A 13.0 "' 1305
B 1h.0 - 1h.5
11.0

13.0

16.0 - 18.0
13.0

 

61

6h - 68
67 - 73
73 - 7h
68

1
76-51.
65

 

South areas of the united States - 12%.

A.
B. Higher moisture limitis applicable because of lower
average air temperatures in producing area during

the storage period.

 

II. MOISTURE MIGRATION AND MOISTURE ACCUMULATION

There are marked changes of air temperatures from“
summer to fall and winter in the Uhited States. Consequent-
ly, temperature differences show up within a‘grain mass
where the grain is stored in large bulk. Grain near the
bin wall and surface cools or warms faster than in the
bin interior. The air, warm or cool, keeps in approximate
equilibrium with the grain. Thus, warm air has' actually a
slightly higher relative humddity than does cool air. The
difference in grain temperatures is responsible for con-~
vection currents which move downward through the cooler
grain and upward through the warmer grain. There is a
slow but continuous exchange of moisture from.the warmer to
the cooler grain due to differences in vapor pressure.
(Figure 5A) The moisture tends to move upward due to the
effect of the rising convection currents taking place
within the central portion of the grain bulk. There the
warmer air rises because it is lighter than the surrounding-
cooler air. As the warmer moist air reaches the cooler
grain near the surface, condensation generally takes place
to a degree depending upon the conditions of the grain and
the atmosphere. (in) (12)

If the grain is cold in the center of the bin as in
the winter, the air currents rise along the surface edges

of the bin during the late winter and early spring. As
-23-

-2u_

I

p
. .. J MOISTURE

 

' '24'372'5’” ’7' '/,u - ACCUMULATION
,r- «439mm; - x
/ ’ ’, fl/{I/f/j ‘,— «’ \
I

' .'
COLD ' WARM COLD
AIR GRAIN ; AIR

‘ COOL COOL I

. GRAIN 6 IN

 

 

 

FIG.5A -— CONVECTION AIR CURRENTS WITH WARM GRAIN
_ IN BIN WITH COLDER SURROUNDING AIR. (l2)

 

   

.- - «a -» ~ \
WARM , COLD I WARM
AIR , GRAIN . AIR
. WARN ',' WARM'
I GRAIN cRmN‘

 

   
  

 

 

COOL sRAnN/ mom ACCUMJLATION

FIG.58— CONVECTION AIR CURRENTS WITH COLD GRAIN
IN BIN WITH WARMER SURROUNDING AIR.(I2)

-25-

the outer layers become warmer, the air currents move down
through the center of the bin to the bottom where moisture
condenses on the cold bottom. The air then moves to the
walls and up along the walls upon being heated. In this
situation the grain spoilage occurs at the bottom or the
bin instead of in the top as explained previoust (12)
(Figure SB) ‘

The most important factors affecting the two state-
'ments are: .

1) The average moisture content of the stored
grain.

2) The size of the storage.

3)‘ The length of the storage period.

A) The atmospheric and grain temperature
differences.

The accumulation of moisture at the surface or at the
bottom of the stored grain may cause: molding, caking and
insect infestation and consequently, the product stored
loses in quality.

As previous studies have indicated, an increase in
moisture content in the surface layer of grain is first
noticed in the late summer or early fall. The relation-
ship between moisture content in the surface layer and in

atmospheric and grain temperature is shown in Figure 6.(23)

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III. HOLD ORWTI'I

Grain is a hygroscopic material and its moisture
content determines the relative humidity of the interseed
atmosphere. Studies on the role of microorganisms in
storage deterioration indicate that mold growth is the
primary cause of spoilage and heating. The relative
humidity of the interstitial air has a pronounced effect
on mold growth and the various species of fungi have
definite limits for growth and reproduction in relation
to minimlm relative humidity. Experimental research on
these limits and many years of practical elevator manage-
ment here in the United States have led to the establish-
ment of maximum moisture levels for the storage of various
grains. (1?)

The mold activity as related to temperature and
relative humidity has been shown that reduction of storage
temperature has a marked influence on the respiratory and
reproductive process of the connon grain storage molds.
The prevalent spec ies of aspergillus molds in stored grain
can grow 10 to 20 times faster at 70°F. than they will at
60°F. Figure 7 shows how a moderate decrease in storage
temperature caused a significant reduction in the per-
centage of germs invaded by storage molds with shelled corn
at 16% moisture content. Thus, with a comparatively short
period of storage, all during cold weather, molding and
insect problems are relatively insignificant.

«27-

-28-

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IV. INSECT ACTIVITY
The damage of stored corn in Brazil due to the attack
of insects in elevators, farmersi bins, corn cribs, etc.,
is primarily due to the granary and rice weevil. Therefore,a
general description of these insects is given below.
1) Classification
Granary weevil - SitOphylus granarius (Linne)
Order: Coleoptera
Family: Curculionidae
Rice weevil - Sitophylus orizae (Linne)
Order: Coleoptera

Family: Curculionidae

2) Distribution
The granary and rice weevil are cosmopolitan. The

first one is probably not native to North America, and the
second one is supposedly a native of India. They are very
frequently found together. The granary weevil is less
prevalent, at least in tropical and semi-tropical climates.
It prefers a temperate climate and is more frequently
found in the northern part of the United States than in the

south. In Brazil, it occurs more in the south than in the

north.
3) Food

Wheat, corn, macaroni, oats, barley, and other grains

and grain products. Adults feed upon.whole seeds or flour

-29-

-30-

but the larvae develop only in seeds or pieces of seeds or
cereal products large enough for them, and not in flour
unless it has-become caked: (19)

u) Life Histggy, Appearance, and Habits

In unheated storages, winter may be passed as larvae
or adults, the latter stage surviving zero oF. weather for
several hours. The adult granary weevil is a somewhat
cylindrical beetle, about 1/6 inch in length. It is dark
brown or nearly black in color, with ridged wing-covers,
and a prolonged snout extending downward from the front of
the head for a distance of about one fourth the length of
the body. (19)

The rice weevil has much the same general appearance,
although on the whole it will average somewhat smaller.
There is a patch of somewhat lighter, yellowish color on
the front and back of each wing cover. A distinguishing
mark is in the shape of the small shallow pits on the
prothorax of the beetles; in the rice weevil these are
round, in the granary weevil they are oval. (19)

The female weevil chews slight cavities in the kernels
of grain or in other foods, and there deposits small white
f eggs, one in a cavity, sealing it in with a plug or gluey
secretion. The eggs hatch in a few days into soft, white,
legless, fleshy grubs which feed on the interior of the
grain, hollowing it out. On becoming full-grown, they are
about 1/8 inch in length. They change to naked white pupae

-31-

and later emerge as adult beetles. The entire life cycle
may be passed under favorable conditions in from four to
seven weeks, they live seven'or eight months, and may
even survive for over two years. The rice weevil has well-
deve10ped wings, and frequently flies, especially during
periods of high temperature. The granary weevil has the
wing covers somewhat grown together and is unable to fly.
(19)

The granary weevil has become more specialized than
the other members of the genus to which it belongs, has
lost the power of flight and is dependent upon.more for its
dissemination. Unlike the closely allied rice weevil, it
is never found breeding in the field. It occurs only in
places where grain is stored. In other respects, the two
insects closely resemble each other in their life histories,
and will very frequently be found associated and working
together in the same bins.

5) Effect of Temperature

Within certain limits, the rate of development and
reproduction of all grain infesting insects increase with
the rising temperatures. A grain temperature of 70°F., is
considered to be the danger line. At that or higher
temperatures, insect populations increase rapidly and
severe damage to stored grain may be expected; whereas
below this temperature level little damage need be
expected. The effect of temperature on the rate of

-32-

reproduction of the granary and rice weevil are shown in
Table 6. (6) .

The abundance-of insects in stored grain is directly
affected by temperature, moisture and food requirements.
The insects that attack stored grain as a group are mostly
of sub-tropical origin and do not hibernate. They did not
develop resistance to low temperatures, so that in the
southern portion of the United States they are in greater
numbers than in the northern portions.

6) Effect of Moisture

The insect pests of stored grains depend on their
food supply for their moisture requirements. Some insects
such as the flour beetle and moths are able to break down
the food supply and thus supply their moisture needs. The
rice weevil and granary weevil are unable to obtain
moisture in this manner. .They are unable to breed in
grain with a moisture content of nine or below nine per
cent, and the adults soon die in dry grain. Little
breeding of these grain weevils occurs where the moisture
content of grain is below 11 percent, unless grain
temperatures are 80°F. to 90°F. The effect of grain mois—
ture on the reproduction of granary weevil and rice weevil
is shown in Table 6. (6)

7) Insect Control
Assuming that the grain is dry enough to store without

heating when placed in the bin and insects are not present,

-33-

there is little danger of insect infestation in the north-
ern portion of the United States. This has been discussed
in the topic "Effect of Temperature on Insects." In the
regions where small grains and corn are produced in Brazil,
however, there is a much greater problem of controlling
insects than in the area mentioned above.

In order to control insects, there are many methods,
and the effectiveness of each one of them depends upon the
skill of the person who is using it. They are:

a) Good house keeping - is one of the simplest and
best ways to prevent insects.

b) using grain protectants
c) Drying and heating sterilization of grain
d) Turning the grain or aeration
e) Fumigating
f) Surface spraying for moth infestation
Using repellents — substances that keep insects
away from crops because of their offensive
appearance, odor, or taste.
8) The use of a protective covering of dust, wood ashes
or similar finely divided material, or the mixing of the
material with grain to prevent insect damage was first
practiced many years ago and has never been entirely
abandoned. When finely divided chemically inert dusts
are mixed with grain, they promote the rapid loss ‘of body
moisture of insects infesting the grain and cause their

death by desication. (6)

 

 

 

 

 

 

 

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V. DRYING OF GRAIN

The principles involved in drying of grain are similar
to air drying of other solid materials. The general idea
in drying of grain is that one is usually concerned with
removal of a limited amount of water from the grain in
order to keep it safely for a period of time. This limited.
amount will depend upon the kind of grain and-other factors
which have been discussed previously. In order to abridge
this discussion we can state: Dry the.grain until it meets
the minimum moisture content required for a safety storage.

0. H. Hall (12) has pointed out the importance of
drying farm crops as follows:

(1) Permits "early harvest" by reducing field loss of
products from.storm, insects, and natural shattering.

(2) Permits "planning the harvest season" to make
better use of labor. Farm crops can be harvested when
drying conditions are unfavorable.

(3) Permits "long time storage” without deterioration.
Extended storage periods are becoming increasingly import-
ant with the large amount of grain being stored and carried
over through another storage year by the government and
industry.

(A) Permits farmer to take advantage of "higher price"
a few months after harvest. In the United States from 19h5
to 1955, the increase in value of corn and wheat from.

harvest to the market peak price was about 25¢ per bushel.
-35-

-35-

(5) Permits "maintenance of the viability" of seeds.
By removing moisture the possibility of heating of the
grain with subsequent reduction or destruction of germina—
tion is decreased. . '

(6) Permits the farmer to sell a "better quality
product" which is worth more to him.and to those who must
use those products.

Water in the Grain

The amount of water which is held by a kernel of any
kind of grain is due to the following reasons:

(1) A certain amount of water may be loosely held in
the intergranular spaces and within the pores of the
material. The water held in this way may be termed as
free water and it possesses its usual properties. In
this situation the molecules of the absorbing substances
are not concerned except as a supporting structure.

(2) Another portion of the water is.more closely
associated with the absorbing substance. There is an
interaction between the water molecules and those of the
substance; in other words, the properties of one substance
influence the properties of the other. In this situation,
water is said to be adsorbed. To denote such interaction
the general term sorption is used, while adsorption and
desorption are used specifically to denote the processes

of taking up and giving off water of sorption.

-37-

(3) The third portion of watermay combine in a
chemical union with the absorbing substance; and conversely,
water which is an integral part of a given substance may
be removed by unduly rigorous conditions at time of

moisture determination. (2)

Representation of Water (moisture content)

The amount of moisture in a product is designated as
the basis of the weight of water and is usually expressed
in percent. There are two methods of designating the mois-
ture centent: a) wet basis, and b) dry basis. The moisture
content on a wet basis is obtained by dividing the weight
of water present in the material by the total weight of the
material. (Equation l—A) The percent moisture on a 951
(235i; is determined by dividing the weight of water by the
weight of dry matter. '(Equation l-B) (12)

Wet basis (% moisture) = Ww x 100 (Equation l-A)

4.

Dry basis (% moisture) : Ww x 100 (Equation l-B)
“‘TEF"

The meaning of the symbols used is:
ww = weight of water Wd 2 weight of dry matter
Both ways are widely used to designate the amount of
water in a product. However, for grains the wet basis is
more commonly used.

Methods of Drying Grain

l. Unheated air Natural ventilation
Forced ventilation

-38-
2. Heated air Direct heater
Indirect heater

3. Infrared drying

u. vacuum.drying

'5. Drying with absorptive substances

In all or these cases, the object of the method is to
make the vapor pressure of the grain higher than that of the
surrounding air, and thus permit evaporation.

Table 7 shows the variation of the moisture content of
sheiied corn (yellow dent) at 0°C., 10°C., 21°C., 30°C.,
38°C., and 50°C. as a function of the relative humidity of
air. This table shows the equilibrium.moisture content of
shelled corn for a particular temperature and relative
moisture content of corn surround by air with a relative
humidity of 70% and a temperature or 30°C. is 12.9 percent.

Table 7 also shows that for a specified and
constant temperature, the equilibrium moisture content
increases as the relative humidity increases.

The Drying Process

When grain or other hygroscopic material is exposed to
an atmosphere at constant temperature, water will evaporate
until the gas pressure of the vapor balances the vapor
tension or the "liquid," water. When equilibrium is reached
the gas pressure is referred to as the saturation vapor
pressure under these conditions. The drying conditions are

Obtained when the atmospheric pressure is unsaturated, that

-39-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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is, lower than the corresponding saturation vapor pressure
at the same temperature. The definition'of the hygrometric
state of the atmosphere can be made in terms of the vapor
pressure as, (a) the "relative l'ui‘niidityu which is the obser-
ved vapor pressure expressed as a percentage of the satura-
tion vapor pressure exceeds the observed value. It can be
shown that for any given temperature the saturation deficit
is equal to Ps (100 - R. H.)/100, where Fe is the vapor
pressure at saturation and R. H. the relative humidity
percent. (22) Therefore, the distribution of saturation
deficit is the inverse of that of relative humidity, but
since the saturation vapor pressure varies directly with
temperature, the saturation deficit for a given value of
the relative humidity is greater at higher than at lower
temperatures. Thus, for example, it is possible to have
a saturation deficit at 70°F. double that at. 50°F.,
although both have R. H. of 85%. (22)
[Egying Grain with Unheated Air

The water vapor of air exercises a pressure or tension
of vapor, but the water which is held by the grain also
develops a vapor pressure. The difference between the vapor
pressure of grain and vapor pressure of the surrounding air
and its equality will determine the direction of the
exchanges of water or their cessation. Dricot, Bruggemans
and Dufey (10) illustrate this phenomena very well with the
use of Figure 10 which on the left gives the vapor pressure

-ul-

in the shelled corn as'a function of its moisture content
for various grain temperatures. The same figure on the
right shows the vapor pressure in the air, as a function of
relative air humidity at various temperatures.

Example 1: If the corn (A1) contains 18% of water and if
its temperature (5:) is 12°C., one can see that its internal
vapor pressure (Cl) will be 9.3 mm of mercury. In order to
determine whether the corn will lose or gain moisture in

the presence of air having these characteristics, the graph
on the right of Figure 10 is used._

Supposing the atmospheric air having a relative
humidity (D1) of 80% and a temperature (El) of 20°C., with
these conditions the vapor pressure of the air is higher
than the vapor pressure of the grain, so the grain will
pick up moisture instead of give it off.

Example 2: Considering the same grain at 18% of water at
the same temperature (31) of 12°C., and having a vapor
pressure (CI) of 9.3 mm.of merCury.

Supposing now the grain is located in air (D2) at.a
relative humidity of 87.5% and a temperature (E2) of 12°C.,
the vapor pressure under these conditions will be also
9.3 mmt So, drying will not occur.

Egggple 3: Supposing that grain (A1) having 18% of water
at a temperature (132) of 20°C. be put in contact with air
having a R. H. (D3) of 65% and a temperature (Eé) of 26°C.,
it is shown from the Figure 10 that the grain will not be

-ug-

able to dry. For the two vapor pressures (03) are equal at
16.6 m. at if the grain temperature (133) rises to 26°C.,
the grain dries, for its vapor pressure (Cu) is 24.3 mm:
higher than the air (C3)

In short we can say that the more the temperature of
the grain is raised in relation to the temperature of the
air, the faster will be the drying.

In conclusion, one can see that the drying-process of
grain with the use of unheated air blowing into the mass of
grain is a function of the weather. When the atmospheric
air is dry and the temperature high, the process will be
satisfactory but if the air is damp and cool the drying will

not take place.

IV. DRYING AGENTS

Chemical absorbents or dehydrating-agents have been
used for drying grain at least experimentally. W. H. Hurst
and H. R. Humphries (l5) conducted an experiment using a
silica gel in mixing with grain (they used samples of wheat,
soybeans, flax, Corn, and rice). The technique used was:
The moisture of the grain was determined and sufficient
water added to increase the moisture content to 20%. After
water was added, the samples were kept in airtight contain~
ers for approximately #8 hours. The drier (silica), the
equivalent of four times the weight of water was added, and
then placed into the container and mixed with the grain by
shaking and tumbling. The container'was then sealed and
allowed to stand for the desired length of time, after
which the figures below were taken.

Weight of sample: 400 grams

Water added: 32.5

Quantity of silica used: 130 grams

Percent of moisture content before wetting: 113.5

Percent of moisture content after wetting: 20%

Percent of moisture content after being mixed with

drier during 96 hours: 11.5

These figures show that n32 grams of corn at 20% I. C. in
mixture with 130 grams of silica lost 40 grams of water.
H. N. Hurst and U. R Humphries have made the following

statement: "Calcium.chloride and sodium.chloride and some
-4L

-hu_
other chemicals‘have'a high affinity for'moisture', but
would doubtless have an injurious effect on grain, and
they deliquesce when saturated with moisture." Recent
work using ua01 and CaClz, however, avoids most of the
objections mentioned by Hurst and Humphries, Dexter
and Creighton. (7) .

S. T. Dexter and J. W. Creighton (7) describe absorbent
blocks which are impregnated with drying salts for imbedding
in stored grain to reduce its moisture. The drying agent
used was calcium chloride in the form of "Dow Flake" due to
many reasons such as: the cheapest desiccant in Michigan,
the advantage of taking up large amounts of water as water-
of-crystallization, has a positive heat of solution, and
it is not in highly soluble harmful to livestock in any
reasonable amount, since both the chloride and the calcium.
ion are common and necessary for livestock. The blocks
were of wood and they have been prepared in the following
way:

The penetration of liquids or gases into woods is more
rapid longitudinally than it is radially or tangentially.
The sap wood is more readily penetrated than the heartwood
in most cases. From.the standpoint of penetration, there
is an advantage of cross-sectional sawing. The blocks so
prepared are, of course, relatively easily broken, but
mechanical strength is not a particularly important factor.
The thickness of these blocks was from 1/2 to 1 inch and

_u5-

1 square inch cross section; After sawing these, they were
placed at one time in boiling calcium chloride solution,
sp.gr. 1.20, slightly acidified to eliminate troublesome
carbonates, and were boiled for 15 mimtes. They were left
submerged in this solution for about 15 hoursand then dried
at approximately 102°C. Some species were by no means
completely impregnated in this length of time. Most of
the blocks failed to float in the solution after impregna-
tion. The following species were exceptions: sassafras,
sycamore, magnolia, catalpa, Peruvian mahogany, and arbor
vitae, in thicker sections. Elm, ash, and beech were found
hard to impregnate inanother experiment. Other methods of
impregnation were also used. Cold impregnation is
possible but is much slower than hot. .11 vacuum system of
impregnation was used with success. (7)

The behavior of blocks as far as relative humidity is
concerned was as follows: at high relative humidities when
impregnated with a solution as concentrated as 1.20 sp.gr.,
blocks of dense wood tend to become moist on the surface,
due to slow diffusion. This is also true of the exceedingly
light woods, which, due to their porosity, have absorbed
an unusually large amount of the solution ; and consequently,
contain a large amount of calcium chloride in comparison
with. the weight of the wood. For example, the dry pieces
of northern white cedar of l/ll and 1/2 inch thickness
weighed 0.91 and 1.74 grams respectively. After impregnat-

-u7-

ing and redrying, they weighed 1.91 and 3.60 grams. They
can absorb more waterthanthey can retain. Corresponding
aspen blocks went from'1.51 and 3.57 grams to 2.79 and
5.66 grams, respectively, by uptake of calcium chloride. (7)
Dexter and Creighton in another‘experiment'found out
that blocks impregnated with solutions of various strengths
were kept at 50% relative humidity for a period, after
which they were transferred to a chamber with a relative
humidity of 75%. ‘At the lower relative humidity, there
was a steady increase in the percentage of moisture
absorbed asothe concentration of the impregnating solution
increased, but at the higher relative humidity the blocks
with a higher proportion of calcium chloride dripped badly,
losing a good deal of the calcium chloride solution that
they were unable to absorb. This statement calls our atten-
tion to the point that the tendency to drain is decidedly
more pronounced in thin (1/h inch) than in thicker (1 inch)
sections. 0n thinner sections, a more dilute solution
should be used as on the very light woods. This avoids
undue surface moisture and yet improves the percentage
uptake of water. It is definitely an. error to believe
that the more the calcium chloride, the better the uptake
of moisture. (See Table 8) Where the solution is too
strong,- the absorbing capacity of the wood is decreased.
A specific gravity of 1.20 would usually be a maximum in
at least the high relative humidities involved in the

-u8-

TABLE 8

Water taken u by blocks of three species of wood impreg-
nated in the ow Flake solutions of various concentrations.

(7)

 

m—-«.-—~“-——.—-—o-— » -- , A . - .H.—_ o...» ---—-.— 9.-....i ——_-— _—..-— . .— - _ _. . A- . -g.-.‘ -yu. 4—..-'~-.. e—-- 9*}

Concentration of impregnating

 

Hater absorbed from.oats solutions
in percentage of:
_i__.i_--- ii, .4. . i_iixiii .MW“i_

“2.91; 30 no- 50 7’6‘0”

r-- «HMM 1‘ J; -I‘ at- r Inn-1.. -

 

 

 

 

Weight of original wood 110 115 90 81 59

VClume of original wood #8 #7 39 3h 25
r.__,,..._......_.. , -.. - H- _-- -_-.1_..-,._._. . -__,.._.,--.__. _ - -1 i ..___.JL.1_._,._1.- -.. .-...... ., --- -._,-- ._ -. A

Weight of dried impreg—

nated block ’ 7h 67 n8 3a 32

Weight of absorbed Dow .

Flake 215 167 103 76 51

 

 

 

 

 

 

 

 

‘ II“I... W ‘4

*grams of Dow Flake to 100 cc water

-u9_

situation considered here. (7)

Other results from-Dexter and Creighton were found
such as: For high relative humidities, above 75%, a sodium
chloride solution may be used to impregnate the blocks.
Other things being equal, it would be anticipated that,
gram for gram, a salt with atoms of small atomic weight
would be more effective than one with heavier atoms. Magne-
sium chloride would appear well adapted for the purpose.

The authors (7) have been using grains and hay with
the blocks, but they used mainly oats and beans. One
thousand pounds of freshly threshed oat grain with 18.5%
moisture were placed in a bin, together with 100 pounds of
dehydrator blocks. At the end of 11 days the dehydrator
blocks were removed and found to weigh 146 pounds. The
cats were found to contain 12.5% moisture at this time.

The conclusions of this experiment are: one advantage
of sodium chloride over calcium.chloride is sodium chloride
blocks dry readily under ordinary atmospheric conditions.
Ordinarily, calcium or magnesium chloride blocks require
artificial heat or low humidity for drying. Blocks of wood
or other porous material impregnated with a suitable pro-
portion of calcium chloride, magnesium chloride, or other
desiccant have been found effective in removing moisture
from.the interstitial atmosphere, and thus from-hay or
grain in mows or bins with this method of reducing the
relative humidity in the storage space, spoilage was

-50-

prevented. Blocks may be so prepared that they will readily
absorb from.50 to 100% or more-of their dry weight.

S. T. Dexter (8) has described a method for condition-
ing popcorn to the proper moisture content for best pOpping.
It has been known that for the best popping, popcorn should
contain about 13.5 percent moisture, by weight. Corn that
is too dry or too wet paps poorly. When stored in the open
air, papcorn commonly dries out until it will give far less
than maximum popping volume. On the other hand, if it is
stored for a few days in very damp air, it becomes too
damp to pop well and may even mold or spoil. Dexter (8) has
stated the following conclusion: Popcorn that has been
grown and dried in such a manner that'it has once possessed
good papping quality may be restored to good papping Qual-
ity in case it becomes too dry. Storage of the corn in an
atmosphere of approximately 75 percent relative humidity
will bring the moisture content up to the desired figure.

.A saturated solution of table salt (sodium chloride),
absorbed by blotters, corn cobs or other material, may be
placed in a closed container with the corn. This solution
provides the proper relative humidity. Corn has been
stored in such containers for more than a year with no
damage to the corn and with the popping quality unimpaired.
No sample was discovered, no matter how old, that could

not be restored to good popping quality, providing that it
had not been injured in the initial drying.

-51-

Another experiment that has been conducted by S. T.
Dexter (unpublished) was the conditioning of beans with a
mixture of sawdust and sodium chloride. The beans were
mixed with the mixture sawdust-salt and then kept in a closed
container. The initial moisture content of the beans was
22 percent, after several days it had become 16.5 due to
the action of the mixture. This little trial has been
kept by Dexter for more than two years and the beans still
have a good appearance. No damage due to insects or
molds has taken place.

0. W. Hall (13) has been conducting an experiment with
calcium.chloride in order to absorb moisture in corn storage.
The reason of this experiment has been already explained
when the author discussed the migration of moisture content
which occurs in stored grains. The conclusions of C. H.
Hall in using calcium chloride to maintain a safe moisture
content in shelled corn stored longer than one year can be
abridged as such: .

a) In 1955 and 1956 in Michigan, six containers of '
calcium chloride in the tOp of 3,200 bushels of shelled
corn in a storage bin kept the moisture content below in
percent when the moisture content of the corn was initially
13.5 percent or less at the time the containers were
installed.

b) Placing calcium.chloride above the grain where

there is an interchange of air from.the outside does not

-52-

prevent moisture accumulation in the surface of the grain.

c) Pellet-type calcium chloride was superior to the
lump-type.

d) Less than six calcium chloride containers per bin,
each container holding 80 pounds, was not satisfactory in
preventing moisture accumlation in the surface of the
grain.

e) The annual cost of Operation for one container
based on a four year life is approximately $2.76. Protec-
tion is provided for the upper two-foot layer of shelled
corn.

f) By coating ferrous metal parts with epoxyl resin
plastic and using plastic screen for covering the metal
frame work, the container and collecting pail did not
deteriorate. The calcium chloride did not damage the
shelled corn next to the container.

Since sawdust, sodium.chloride, and calcium.chloride
were used in the experiment to be described, certain facts
concerning them are apprOpriate.

l) Sawdust (wood)

A) Hardwood and Softwoog_

 

The trees are divided into two classes:
‘hardwood and softwood. Hardwoods, such as elm, oak, cherry,
beech, and bass wood have broad leaves. Some softwoods or
conifers, such as the cedars, have scale-like leaves, while

others such as the pines, Douglas fir, and the spruces,have

-53-

have needle-like leaves. We have to be careful when men-
tioning the terms hardwood and softwood due to the fact that
they are not directly associated with the hardness or soft-
:ness of the wood. In fact, such hardwood trees as cotton
'wood and yellow poplar have softer wood than such softwoods
as longleaf pine and Douglas fir. (21)
b) Sapwood and Heartwood

Sapwood plays an important part in a tree's
living process. Generally, only the last few outside
layers of the sapwood are alive. The rest carry moisture
from the roots to the leaves and store food for the tree.
As far as moisture content is concerned sapwood has a
higher moisture content than heartwood. (21)

During the life of a tree, sapwood gradually changes
into heartwood, and becomes less permeable as the cell wall
thickness and the cell opening become smaller.‘ Since
moisture movement is thus retarded considerably, heartwood
dries more slowly than sapwood. In general, heartwood is
darker in color and also more resistant to decay than sap-
wood. (19)

c) Equilibrium.loisture Content
The amount of water in sawdust is spoken of
_as its moisture content, and is usually expressed in terms
of percent of moisture content - dry basis. However, we
think it is useful to use the moisture content in terms of

wet basis due to the moisture content of grains being

-5u-

always expressed in percentage wet basis. Any piece of
wood (sawdust) or any hygroscopic material is said to be in
equilibrium moisture content when it no longer gives off or
picks up moisture, but is in balance with that in the
surrounding atmosphere. The percentage of moisture in the
sawdust at this point is called the equilibrium moisture
content. The equilibrium moisture content of sawdust at
different relative humidities and in some constant tempera-
tures is shown in Figure 8. A curve resulting from plotting
the equilibrium.moisture contents on the ordinate and the
respective relative humidities on the abscissa at a constant
specified temperature is called an "isotherm". This
relationship is illustrated in Figure 8, which shows, for.
example, that sawdust kept in air constantly at 80°F. and
75% relative humidity will eventually come to equilibrium
at a moisture content of about 12.5 percent (wet basis).
Similarly other isotherms are shown on the same graph
using temperatures of 60°F. and 70°F. (21)
d) How Sawdust Dries
Most woods have a microscopic structure

rather similar to a bundle of long connecting capillary
tubes, rather than that of a foam (disconnected) bubbles.
This anatomy is important in its use as a drier.

Chemically, wood consists mainly of cellulose, hemi-
celluloses, and lignin. These substances have a strong

affinity for water, which explains why dry wood or sawdust

-55..

absorbs moisture from the air, when the humidity is high.
(20)

N In sawdust, water occurs in two forms: as free mois-
tggg_in the cavities of cells, and as bound moisture held
within the cell walls. When sawdust dries, the free
moisture is removed before any bound moisture can be with—
drawn from the cell wall. The reverse is of course true
when dry sawdust is allowed to_absorb moisture, i.e., no
free moisture can form*within the cell cavities until the
cell walls have been completely saturated. Technically,
this state, where there is no free moisture in cells but
the cell walls are fully saturated, is known as the fiber
saturation point. (20)

Water in sawdust (wood) normally moves from zones of
higher to zones of lower moisture content. This fact
supports the familiar statement that "wood dries from the
‘outside in," which means that the surface of the wood must
'be drier than the interior if moisture is to be removed.
(21). Similarly, the same happens with sawdust (pieces of
wood), and since the size of particles of wood are smaller,
tame amount of water in the surface and in the interior
wtmuld be practically the same.
lk>isture in wood moves as liquid or vapor through several
kixads of passageways. These consist of the cavities of
fitaer and vessels, wood ray cells, pit chambers and their

911: membrane openings, resin ducts of certain softwoods,

-56-

other intercellular spaces, and transitory cell-wall
passage ways. Host of the moisture lost by wood during
drying moves through cell cavities and the small openings
in the cell walls. Moisture moves in these passage ways
in any direction, longitudinallyas well as laterally.
Lighter woods in general dry more rapidly than do the
heavier woods. (20) However, if we are concerned with
sawdust, there is no difference; if there is any it should
be very small and we can neglect it.

The reasons of movement of water during the drying
or wetting process of sawdust are as follows: (21)

l) Capillary action, which causes free water to flow,
for the most part, through cell cavities and small openings
in the cell wall. '

2) Differences in relative humidity in the sawdust
that causes water vapor to move through various passage-
ways by diffusion.

3) Differences in moisture content that move the
bound water through the small passageways in the cell wall
.by diffusion.

‘ The factors which influence the drying rate or the
wetting rate are: -

The rate at which moisture moves into sawdust or moves
out from sawdust is dependent upon the relative humidity
of the surrounding air, the steepness of the moisture'

gradient, and the temperature of the sawdust, the lower the

‘-57-

relative humidity, the greater the capillary flow. Low
relative humidities also stimulate diffusion by lowering
the moisture gradient. The higher the temperature of the
sawdust, the faster will be the rate at which the moisture
moves from the wetter interior to the drier surfaces. (21)
For the opposite reasons, the same will take place when
dry sawdust is mixed with wet grain.

e) Composition of Sawdust

' The average plant-nutrient content of saw-

dust in comparison with wheat, straw, and alfalfa hay is
given in Table 9.. It will be observed that sawdust is

extremely low in nitrogen, phosphorus and potassium. (1)

TABLE 9

Quantities of the principal plant nutrients contained in
various plant products, per ton of dry matter. (1)

 

 

 

 

 

Dry material Nitro en Phosphorus Potash Lime Mag.
(in lbs.) (N_ (P205) (K20) (CaO) (H30)
Sawdust h 2 h 6 0.5
Wheat straw lO 3 12 h 1.2
Alfalfa hay #8 10 4 28 28 7.0

 

 

 

 

 

 

f) §2ecific Gravity
The specific gravity of the woods (sawdust)

which have been used in this proJect are:

(l) Basswood (Tilia americana) sp.gr. - .32

 

~58-

(2) Beech (Fagus grandifolia) 8p.gr. - .56
(3) Cherry (Prunus serotina ) sp.gr. - .h7
(4) Elm (Ulmns americana) sp.gr. - .h6

All are hardwoods.

2) Sodium.0h19ride (HaC1)

Salt, sodium chloride, has probably been with us
from the beginnings of geologic time, and has probably
always been necessary either directly or indirectly through
all stages of the evolution of living things. The import-
ance of salt in all recorded civilizations may be gauged
by the number of salt words in contemporary literature.
With the exception of water, no other chemical substance is
mentioned so often. (18)

Composition

In natural occurence salt is never found absolutely
pure. Average analysis of large quantities of salt as
mined may run.we11 over 98 percent. The most common
insoluble impurities in salt stocks are anhydrite, dolomite,
calcite, pyrite, quartz, and iron oxides. The most common
soluble impurities include the following ones: Ca, Mg, K,
Cl, co , and son. (18)

Occurence

The various occurences of salt can be classified
geologically as follows: (18)

1) Salt in Solution 2) Dry Deposits

a) Ocean water a) Playa salts

-59-

b) Lake water b) Bedded salts
c) Ground water c) Flowage salts

Physical Properties

Doubtless, sodium chloride has been subjected to
every known physical test. A

Studies of grain storage in closed containers
with air at various relative humidities showed that molding
occured at more or lessiconstant relative humidities of
the air surrounding the particles of grain. The air in the
bin between beans at 16% moisture content may be as damp
(75% R. H.) as the air between flaxseeds at 10%, or wheat
at lhfi. (9) Thus, it is now quite generally agreed that
the so-called critical moisture level for any individual
species is the percentage at which the seed is in equili-
brium with an atmospheric humidity of about 75%. (2) From
that statement, we have concluded that the way to maintain
an environment of 75% relative humidity to materials in
storage is with the use of a saturated solution of sodium.
chloride.'

Figure 9 shows the vapor pressure curves for water and
for a saturated solution of sodium.chloride. (18) The
figures given at the various temperatures on the sodium
chloride curve are the ratios of the vapor pressure, or the
relative vapor pressure (relative humidity) of the air over

the salt solution. Supposing the dry bulb reading to be

-60-

15°C. and the wet bulk (NaCl) reading 13°C. as located by a
circle on each curve. The curve shows that these would
correspond to vapor pressures or approximately 9.2 mm and
13.5 mm or a relative humidity of 9.2/13.5 or 68% which

is somewhat drier than necessary for safe storage. In
general, if the wet bulb (NaCl) is 1°C. colder than the dry
bulk, the grain should store without trouble, usually about
71%. (9) Hilner and Geddes (2) consider 7h$ R. H. or less,
sufficiently dry for ordinary storage of dry grain. Table
10 shows the vapor pressure and corresponding relative

humidity of saturated solutions of NaCl.

uses of Salt (HaCl)

Among the "big five" (the primary raw materials - salt,
sulfur, limestone, coal and petroleum), salt is unique in
versality and number of uses, due to application of a
large number of its physical and chemical properties. The
following brief list contains both large and small uses.
(18):

a) Deliquescence: Removal of water vapor from air
and gases; removal of water haze
from.turpentine, gasoline

b) Freezing point depression: Ice and snow removal
from streets; refrigerant , brines ,
etc.

c) Nutritiveness: Human and animal foods; fertili-

zers; fermentation industries, etc.

-61-

oo-

:N-..-.m303<m mom ms-mUI-bm-

 

.53 and {to-2:... naked-a ans-350m

ZO-kn-mommo I m .0:-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OG 00 o» 00 on ow om GAO
N
v
\ \
\x o
L1 \\ O
\

\\ O-
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W -\

boom Ullllb
woo... Ollie e.

n“ woom I
I-I @-

 

 

Ow

susvs 13M iwaosad ‘iwaiNoo asnisow

 

SATURATED VAPOR Peessuae — Mm. wescusv

 

-62_

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

95 I}?
so.
as A————A WATER
m——. SAT.SOL.NOCI. /
8' /
75 /
70 /
es
,0 // //
55 j /
5 / /
45
4 / 14.2%....
35 / /
K /
3. /
2.5 /
/ 75.1%“.
2 A“?
I5 ”firman
:0
74.9%

5 7 /

new,
0 .-

C. I0°c. oc. OC. 00. '
32°: 50°F? 33°»: 39% no?” :2

 

 

 

 

 

 

 

FIG.9- THE CURVES SHOW THE SATURATED VAPOR PRESSURE

OF~WATER AND OF A SATURATED SOLUTION OF NOCI .
OVER THE TEMPERATURE RANGE OF OTO 50°C. AND

ALSO THE RATIOS OF THE TWO

INTERVALS. ( 9XI8)

c.
0F.

-53-

 

— VAPOR PRESSURE- mm MERCURY —

 

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39-0- <b-uom tmmmmcmm -2 oomz.>w b mac-40452 O... -._.m ZO-wflcmm
002.324 mom (hm-Ocm orb-2 amz-uNmDHC-wmw. >20 _2 41m b-m.>m b

fiCZ-ZOZ Om. _._.w mmr>fi<m ICE-02.4 >4. (bx-Ocm fimZ-ummbficmmmnoo.A-O-

_5u-

TABLE 10

 

vapor Pressure and Relative Humidity of Saturated
Aqueous Sodium Chloride Solutions. (18)

 

 

 

 

 

 

 

 

Temperature Vapor Pressure (nu Hg) Equilibrium

Relative

00 F0 Sat. Sol. H20 Humidity

HaCl _

o 32 3.5 11.579 76.1%
10 50 6.9 9.209 74.9%
20 68 13 .2 17 . 535 75 . 3%
30 85 23.9 31.824 75.1%
ho 10h 41 .6 55 .324 75 2%
50 122 69.5 92.510 75.1%

 

 

 

 

 

Preparation of Saturated Salt Solutions

\

In order to saturate 100 grams of water, the weight of
salt required in grams is:' (12)

 

 

 

 

 

 

 

 

 

 

 

 

Chemical Tegperature figight
NaCI (Sodium chloride) 10 50 35.8
20 68 36 .0

30 86 36.3

IIO 10h 36.6

Ca012(Calcium.chloride) 20 68 59.5

’ ' 30 86 - 7n .5

i no ' 104 102 .0

 

 

 

 

-55-

d) Taste: Flavor for foodstuffs, stimulant of sweet
flavors, etc.
e) Toxicity: Weed and algae killer, fungicide,
germicide, bactericide
f) Preservative action: Curing meats, hides and
skins; preserving dairy products, vege-
tables, fish and shellfish, etc.
g) vapor pressure: Desiccant, air dryer; wood curing
agent.
As we can see, salt has a tremendous application, and
we hape very soon to include in this list the property
of drying and keeping grain safely with its use in combina-
tion with sawdust and other absorbent materials.
3) Calcium Chloride (CaClgl ‘
Composition .

The content of actual calcium-chloride in
commercial solid calcium-chloride is from.73% to 75%, and
in flake calcium chloride, it is from.77% to 80%, the
balance being principally water of crystallization with a
small amount of salt (NaCl). Magnesium chloride is absent,
thus precluding the danger of corrosion.

Properties

Calcium chloride dissolves readily in water;
in fact, it has such an attraction for water that when
exposed to air under ordinary conditions, it absorbs

atmospheric moisture until the calcium chloride is

-55-

dissolved. Its solutions are relatively stable. Such a
property mines it a strong drying agent, and its wide use
in chemical laboratory as a desiccator.

Table 11 shows the vapor pressure and corresponding
relative humidity of saturated solutions of' Ca012. The
relative humidity is calculated from P/Po, where P.= vapor
pressure of saturated air and Po = partial vapor pressure
of water.

Other prOperties and uses of calcium.chloride were

mentioned already when we covered the topic "Drying Agents."

TABLE 11

vapor Pressure and Relative Humidity of Saturated
Aqueous Calcium Chloride Solutions. (16)

 

 

 

 

 

 

 

 

 

Te?erature Va or Pressure ma 'Equil ibrium
. . . 01. Relative
08012 Humidity
0 32 2.08 n.579 45.u$
10 50 3.71 9.209 “0.3fi
20 68 6.06 17.535 38.5%
30' 86 7.22 31.821: 22 .636

 

 

 

* Computed

MATERIALS AND HETHODS
I. SHELLED CORN, DRYING AGENTS, AND INSECTS USED:

The corn used in the first stage of this experiment
was a yellow dent hybrid which had been stored at O°F. for
a period of eight months. It had an average moisture
content (wet basis) of 30%. A portion of this corn was
dried at room.temperature (approximately 77°F.) in order
to reach 205 moisture content.

In the second stage of this experiment, the corn used
was a yellow dent hybrid which had been stored in an
elevator for a period of more than one year. It had an
average moisture content of 12.5%. This corn was wetted
to 22.5% and was used in the final experiment.

The drying agents which were used are: sodium-
chloride (table salt and rock salt), calcium.chloride, and
dried sawdust which was screened through a 12/6h inch round
hole screen. The dried sawdust was a mixture from four
different woods: beech, elm, cherry, and basswood.

The insect used to test the DRIERS as an insecticide
or an insect repellant was the granary weevil (adults)
(Sitophylus granarius - Linne). ‘

II. PREPARATION OF "DRIERS"

Several mixtures of sawdust and salt were prepared

using different concentrations of salt. These mixtures

will henceforth be designated as:

-68..

DRIER - Nas (1 part NaCl : 5 parts sawdust)
DRIER - N310 (1 part NaCl : 10 parts sawdust)
DRIER - Na20 (1 part NaCl : 20 parts sawdust)
DRIER - Ca5 (1 part CaClz: 5 parts sawdust)
DRIER - CalO (1 part CaCla: 10 parts sawdust)
DRIER - Ca20 (1 part CaCle: 20 parts sawdust)
DRIER - 8 (plain dried sawdust):

The term.DRIER refers to the combination of sawdust
and salt either NaCl, CaClz, or only plain dried sawdust.
Na refers to sodium chloride and the number following it
refers to the preportion of sawdust as can be seen above.
Ca refers to calcium.chloride with the same notation as
used for sodium, i.e., DRIER - NalO - 1 part of sodium
chloride (#0 grams) to 10 parts of dried sawdust (“00
grams). The prOportions given as the examples refer to
concentration by weight, not by volume.

In order to describe how the "DRIERS" were prepared,
the DRIER - Nalo may be taken as an example. Supposing
that about 500 grams of the mentioned drier is needed. Then
to prepare it, the following steps were followed: I

l) Weigh 50 grams of sodium chloride and 500 grams
of dried sawdust.

2) Prepare an aqueous solution of the salt. The
quantity of water has to be sufficient to wet the 500
grams of sawdust because in this way the sawdust will be

impregnated with the solution of sodium chloride. Different

-59-

quantities of water have been used to prepare the DRIERS
and based on these results, an amount of water equal to
about 1/3 of the weight of sawdust.is needed to prepare
the salt solution. Thus, there will be 35 grams of water
for each 100 grams of sawdust. In this example, 175 grams
of water (about 1/3 of the weight of the sawdust) should
be used to dissolve the salt. The quantity of water
indicated as percentage of the weight of the sawdust (35$)
was used to prepare all the DRIERS.

3) After preparing the salt solution, it is mixed
thoroughly with the sawdust. The damp mixture was placed
in an oven at 180°F. for 2h hours in order to obtain the
DRIER. To mix the sawdust with salt solution is very easy.
With small quantities it can be done with the use of hands;
otherwise, in large scale as used in the second stage
it can be done with a shovel. (See Figure 110)

III. PREPARATION OF MIX

Different quantities of DRIER in relation to the
quantity of wet shelled corn were also used in this
experiment, and for these proportions of DRIER to shelled
corn the following notations were adopted:

EEEEBEEEEEEEEéBEEEEBEEEEE

NaS
NaS
nus
ns5
N35
Halo
Nalo
Nalo
Halo
Halo
NHZO
uszo
naao
waao
uszo
Ca5
Ca5
C35
Ca5
Ca5
CalO
CalO
CalO
CalO
CaIO

-70-

( 1 part corn

(3
(5
(8
(10
(1
(3
(5
(8
(1o
(1
(3
(5
(8
(1o
(1
(3
(5
(8
_(10
(1
(3
(5
(8

parts
parts
parts
parts
part

parts
parts
parts
parts
part

parts
parts
parts
parts
part

parts
parts
parts
parts
part

parts
parts

parts

(10 parts

corn
corn
corn
corn
corn
corn
corn
corn
corn
corn
corn
corn
corn
corn
corn
corn
corn
corn
corn
corn
corn
corn
corn

c ODD

P‘ 0* P' r4 (a P‘ be P‘ +4 (H P' ta ta ho rd Id h’ F4 (a F‘ ta ta F‘ r4 Ia

DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER
DRIER

N35 )
11:5 )
Na5 )
Na5 )
N85 )
Nalo)
NalO)
RalO)
NalO)
NalO)
uszo)
Na20)
Na20)
nszo)
sto)
0&5 )
Ca5 )
Ca5 )
Ca5 )
Ca5 )
CalO)
Calo)
CalO)
cuo)
CalO)

-71..

MIX - l, Ca20 ( 1 part corn : 1 part DRIER - Ca20)
MIX - 3, Ca20 ( 3 parts corn : 1 part DRIER - Ca20)
MIX - 5, Ca20 ( 5 parts corn : 1 part DRIER - Ca20)
MIX - 8, Ca20 ( 8 parts corn : 1 part DRIER - Ca20)
MEX - lO, Ca20 (10 parts corn : 1 part DRIER - Ca20)
MEX - l, S ( 1 part corn : 1 part DRIER - 3)
MIX - 3, S ( 3 parts corn : 1 part DRIER - 8)
MIX - 5, S ( 5 parts corn : 1 part DRIER - 8)
MIX - 8, S .( 8 parts corn : 1 part DRIER - S)
MIX - 10, S (10 parts corn : 1 part DRIER - S)
The term."MIx" refers to the mixture of shelled corn

and DRIER. The first number after the word MIX refers to
the quantity of corn in proportion to the quantity of DRIER.
The symbols Na5, CalO,S, Nalo, and so forth, are referred
to as the DRIER which had been used to prepare the specified
MEX. In all cases, the proportions given refer to quanti-
ties by weight, and not by volume. To illustrate, an
example is given below.

In order to describe how the MIX was prepared, the MIX
3 Ca20 may be used as an example. Supposing that we have
300 grams of wet shelled corn and we would like to use the
DRIER - Ca20 as the drying agent to dry it by the use of
MIX - 3 Ca20.
may be followed:

1) Weigh-100 grams of DRIER - Ca20 that has been

Then to prepare it, the following steps

prepared as indicated previously.

-72;

2) Put the 300 grams of wet shelled corn and the 100
grams of DRIER - Ca20 in a container (bottle), seal it with.
a lid, shake the container to mix the corn with the DRIER,
and then keep it in an appropriate place.

3) An even mixture can be prepared by shaking the
corn with the DRIER in a bottle. Hewever, when the quanti-
ty of shelled corn is increased as in the second stage of
this study, the author advises mixing them in smaller
containers before filling the bins (See Figure 11D).

V. MEASUREMENTS (WEIGEING)

An oven method was used to determine the initial
moisture content (wet basis) of the shelled corn. To
compute the moisture content due to the effect of drying
agents the following procedure was used:

At intervals after preparing the MIX, the corn was
_ removed on a u/16 inch square hole screen. The shelled
corn was then weighed. (See Figures 11A and 11E) From
this weight the moisture content was computed by using the
following equation:

lsC.W.B. = 100 - Y

Y = Initial weifiht of S.C. x X

Final weigh1 of . .

Where: M.C.W.B. — Moisture content wet-basis

 

3.0. - Shelled corn
X - Percentage dry matter (initial)
Y - Percentage dry matter (final)

-73-

Supposing 200 grams of 8.0. at 20% M.C.W.B. has been
mixed with DRIER, and that after 2 days in the MIX, the
weight of 8.0. was 180 grams. Therefore, the M.C.W.B. will
be:

X 3 80%
100 - 20% M.C.W.B. 3 80% Dry matter

y I: 200 x 80 = 88.88%
186 '

11.03.13. 5 100 - 88.88% = 11.12%

 

 

Figure 11A — Weighing shelled cornaand showing
equipment used during laboratory experiments.

 

 

 

Eigure llE — Dr. S. T. Dexter andrthe author with
the material used in the large scale experiment
(corn in bags, salt, and sawdust).

 

 

rigiEé‘i:c“T"sBo?eiiEBg"§E&&us£ with salt solutions
in preparing the DRIER. ‘

-75-

   
 
 
  
  

Figure llD —

Filling the Bin
With MIX — 3 NalO.

_- f...

...--:M‘!. .' wim1‘.qf§n“f

 

Figure 11E - Screening to remove the sawdust before
weighing the dried corn.

RESULTS
I . PRELIMINARY EXPERIMENTS

A. 'DRIER - Na5, DRIER - Halo, and DRIER — Na20

With these DRIERS, the following MIXES were prepared:
DEX-3M5,MIX-3Na10, MIX-3Na20,MIX-5Na5, MIX-
5 NalO, MIX - 5 N820, MIX - 10 N85, MIX ’— 10 NalO, and MIX -
lfilazo.

A sample of 200 grams of shelled corn at 30% MWC.W.B.
was used in each one of these MIXES. The bottles filled
with the MIXES were kept in a temperature-control chamber
at 80°F. and the measurements were made at intervals of
3., 2, h, and 6 days as shown in Table 12.

Table 12 shows that the minimum.moisture content
reached was 18.13% in MIX - 3 Na5 and 19.15% in MIX - 3
Nalo. In the others, the moisture content was greater
‘tdaan 20$.

Mold growth was observed in MIX - 10 Has, MIX - 10 NalO,
and MIX - 10 Na20 at the fourth day; in MIX - 5 Na20,
MIX - 3 Na20 at the sixth day. In the other during the
first six days mold growth did not take place. we bottle
with plain shelled corn at 30% M.C.W.B. was kept under
the same conditions and mold growth started at the second
day.
go DRIER - Ca5, DRIER - 0310, and DRIER £8.20

The same experiments conducted in A as far as MIX,

 

*T'Ee am chloride used in this experiment was table salt,
c>l'lly in the experiment conditioning the MIX in bins was the

rock salt used .
-76-

-77-

TABLE 12

The drying of shelled corn (30% M.C.W.B.) when conditioned
in sealed containers at 80°F. with: MIX - 3 Na5; MIX - 5 Na5;
MIX - 10 N25; MIX - 3 Halo: MIX - 5 N310; MIX - 10 N810;

"IX - 3 No.20; MIX - 5 N820; and MIX - 10 N320.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TIME WEIGHT MOISTURE WEIGHT MOISTURE WEIGHT MOISTURE
CORN CONTENT CORN CONTENT com CONTENT
DAYS GRAMS as GRAMS :6 GRAMS st)
fMIX-3Na5 “*Mix-suas (flux-101125
0 200.00 30.00 200.00 30.00 200.00 30.00
1 178.00 21;; 181.00 22.65 18640 24.91
2 172.10 18.65 179.10 21.81: 186.119 211.99“
8 171.50 18.37 178.30 21.53 W 386.35 211.81“
6 171.115 18 .35 178.30 21 .50 186.35 211.87. *
*MIx - 3 NalO H *Mxx - 5 Halo fMIx - 10 NalO
0 200.00 30.00 200.00 30.00, 200.00 30.00
1 179.10 21.9? 383.11? w#2337 186.60 211.98
2 1711.50 19.77 179.90 22.18 185.70 211.60
a 173 . 9O 19 . 50 179 .80 22 . 1a 185 . 70 2a . 6O
~6 173.80 19.u5 179.80 22.1u 185.65 2u.58
*MIx — 3 Na20 *MIx - 5 Na20 __ *MIx -~10,Na20
0 200.00 30.00 200.00 30.00 200.00 30.00~
._ 1 181.52 22.88 185.30 20.15 189.20 26.00
; 2 178.70 21 .76 182.60 23.33 188.00 25.50
‘_ a. 177.70 21.22 182.110 23.25 188.00 25.50
4; 6 176.70 . 20.77 182.00 23.10 187.90 25.118 7

 

 

 

 

 

 

 

 

 

*See-pages 70, and 71

for the meaning.

-78-

sample of corn, and temperature control are concerned were
followed with these DRIERS. The measurements at intervals
of 1, 2, h, and 6 days are shown in Table 12A.

Table 12A shows that the minimm moisture content
reached was 18.04% in MIX - 3 Ca5 and 19.08% in MIX - 3 Oslo.
In others, as in the experiment with sodium chloride, the

moisture content was greater than 20%.
As far as mold growth is concerned, the same results

which were observed with the use of DRIER - Na were obser-
ved with the use of DRIER - Ca.
0 . DRIER - S

With this DRIER, the following MIXES were prepared:
"IX - 3 S, MIX - 5 S, and MIX - 10 S. The shelled corn used
was the same used in A and B and the bottles with the MIX
were kept also in a temperature-control chamber at 80°F.
The measurements followed the same procedure as in A and
B and they are shown in Table 128.

Table 12B shows that the minimum moisture content
reached was 23.92 with MIX - 3 S and the maximum 27.70%
with MIX - 10 S.

Mold growth was observed in all of the MIXES at the
Second day as in the bottle with plain shelled corn.

From these experiments, the author decided to eliminate
the DRIERS: Na5, Na20, 005, and Ca20 due to the following:
1 ) DRIER - Na5 and DRIER - Ca5 have almost the same effect
°f DRIER - NalO and DRIER - Ca10 as far as drying shelled

-79-
corn is concerned, and 2) DRIER - Na20 and DRIER Ca20 have

atlmost the same effect as DRIER S as far as drying and mold

Egrowth are concerned.

-80-

TABLE 12A

The drying of shelled corn (30% M.C.W.B.) when conditioned

in sealed containers at 80°F. with:

MIX-30853MIX-5085;

”IX - 10 035; MIX - 3 0310; MIX - 5 .0310; DEX - 10 CaIO;

MIX-303203MIX-50820;andMIX-100a20.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[ TIME WEIGHT MOISTURE WEIGHT MOISTURE WEIGHT MOISTURE
D... .391” ”"9?” £218 W?“ .222: WT“
fMIx - 3 Ca5 l m - 5 Ca5 *MIX'- 10 005mm
0 200.00 30.00 299.00 30.00 200.00 30.00
‘ 1 174.82 19.92 177.00 20.90 186.95 25.12
2 171 .00 18.13 175 . 50 2o .20 186.90 25 .10
4 170.90 18.10 175.50 20.20 186.90 25.10
E 6 170.80 18.04 175.40 20.15 186.80 25.06
'MIx-3cs10 J flux-509.10 A *MIx-1ocs10
0 200.00 30.00 200.00 30.00 2L00.00 30.00
1 178.50 21 .53 181 .30 22 .88 187 .70 25 .42
2 174.30 19.68 179.80 22.16 186.60 24.98
4 173 .40 19 .27 179.50 22 . 00 186 .60 24 .98
6 173.00 19.08 179.404 21.97 186.50 24.94-
fMIX - 3 C820 'MIX - 5 Ca20 H .141ij
0 200.00 30.00 200.00 30.00 200.00 30.00
__ '1 180.70 22.53_ 184.52 24.13 190.30 26.44
‘2 179.10 * 21.84 182.80 23.42 189.20 26.00
(‘4 179.00 21.79 182.80 23.42 189.10 25.97
.\6 178.90 21.75 ’ 182.70 23.38 189.00 25.93 {

 

 

 

 

 

 

 

 

 

 

 

*See pages 70,and 71 for the meaning.

-81-

TABLE 12B

The drying of shelled corn (30% M.C.W.B.) when conditioned
MIX - 3 S; MIX - 5 S;

in sealed containers at 80°F. with:

andMIX-lOS.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

“-

m "23:? 8W "ERR Raw ERR Raw
DAYS GRAMS % GRAMS % GRAMS 5
*MIx-3S (fax-53 [wigs
0 200.00 30.00 200.00 33.00 200.00 30.00
‘ 1 187.20 25.22 190.50 26.j1__ 194.90 28.17
2 185.20 24.40 189.60 26.17 194.50 28.13 ‘
4 184.59 24.12 189.60 26.17 193.70 27.73
5 18h.00 23.92 189.03 25.93 193.60 27.70

 

 

 

Percent moisture content (wet basis)

 

 

II, EXPERIMENTS WITH DRIER - N310, DRIER - 0310, AND

A. DRIER - N810
Three samples of shelled corn at 20% M.C.W.B. weighing

100 grams each were mixed with DRIER - N310 in order to
make the MIXES: MIX - l N310. Three similar replicates
were made of the following MIXES: MIX - 3 N310, MIX - 5
N310, MIX - 8 N310, and MIX - 10 N310. The bottles filled
with these mixes were kept in a temperature-control chamber

at 80°F.
The corn was screened from the mix and weighed at

intervals of 1, 2, ll, 6, 8, and 10 days. After the tenth
day, the bottles were transferred from the chamber to a
room without temperature control and at the 30th day the
13st measurement was taken as shown in Table 13.

Table 13 shows that at the end of six days the mini-
mum moisture content reached was 12.40% in MIX - l N310
and the maxim 17.02% in MIX - 10 N310. However, in MIX -
3 N310 at the end of the same period of time the moisture
content reached was 14.17% which is satisfactory for the
storage of shelled corn due to the fact that mold growth
did not take place. Table 13 also shows that the moisture
c=<>ntent at the end of ten days and at the end of 30 days
Were practically the same, leading to the conclusion that
Variation of temperature had no effect on the DRIER - N310.

Mold growth was observed on MIX - 8 N310 and MIX -
10 N310. In the first one, mold started at the end of 15

days and in the second one at the end of ten days.
-82..

-83—

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2.24 8.8 8.2 8.8 8.2 8.8 8.2 8.8 2.2 2.8 H
8.8 862 8.8 8.02 8.8- 8.02 18.8. 8.82 8.8 8.82 0
2022-3“ 22¢-fixh 202m..x=.s__202m-fi:w 2022-52.
Samson fimo Emmzoo mauve Emmzoo flame Eumzoo zmnmwo Summons flaws 23.
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.onoz 0H 1 NH: poo .oaoz m 1 NH: .onz m . xH: .onz m 1 NH: .oaoz a 1 me
"and: .moow no 20:82.00 .8an a." 7836.: $08 930 00308 no 3280 05.

ma mama.

 

_gg DRIER - Calo

Similar experiments were conducted with DRIER - CalO
in the following MIXES: NIX - 1 Oslo, MIX - 3 Oslo, KIX -
5 Oslo, MIX - 8 CalO, and MIX - 10 CalO. (See Table 13A)

Table 13A shows that the mininum moisture content
reached at the endof six days was 12.31156 in MIX - l Ca10
and the maxim 16.90% in MIX - 10 Calo. 'In MIX - 3 08.10
the moisture content reached was 13.76% which is also
asatisfactory for storage of shelled corn.

The variation of moisture content from the tenth to
the 30th day can be neglected as shown in Table 13A.

Mold growth was observed in MIX - 5 03.10, MIX — 8 Oslo,
and MIX - 10 08.10, in the first one at the end of 30 days
in the second at the end often of ten days, and in the
last one at the end of eight days.

So far, the data show that as far_as drying of shelled'
corn is concerned, the DRIER - Oslo and DRIER - Nalo have
about the same properties. Nevertheless, from the stand-
point of mold growth, sodium chloride has more fungicidal
action.

0 . DRIER - S
The same procedures which had been followed in the

 

experiments conducted with DRIER - 0:110 and DRIER - Nalo
were used with DRIER - S in preparing and keeping the
following MIXES: MIX - 1 3,111): - 3 3, MIX - 5 s, and xxx

“ 10 S. The measurements are shown in Table 138.

-85-

8553. 2.3 sou 2. and om. 3on 0mm *

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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5. 2 mm. 8 :0. 2 8. 8 mm. 2. 2.. am is. 2 «a. 8 8. 2 8.8 2
18.2 .88 8.2 8.00 mm. 2 2.3 me. D 8.8 3.3 08.8 m
om.ma 0N.mm mm.md mm.mm om.mH mb.:m m>.ma mh.mm :M.NH mm.om m
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-86-

Table 13B shows that at the end of six days the minimum
moisture content reached was l3.1h% in MIX - l S and the
maximum 18.92% in an — 10 s. *

Hold growth was observed in HIX - 3 8, MIX - 5 3,

MIX - 8 S, and HEX - 10 S. In the first and second one at
the end of eight days, and at the end or six days in the
other two.

A sample of shelled corn at 20% H.C.W.B. was kept
under the same conditions and the mold started to take

place at the end of four days.

0222.806 on» .200 20 Us.» 00 000.00 000...

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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a<a

 

III. Expsamurs ms DRIER - Nami DRIER - chic, AND

After preparing the Damnswamn - NalO, DRIER - Oslo,
and DRIER - S), they were left for three days spread out on
a table at room.temperature. The following figures were

taken under these conditions:

DRIER - CalO DRIER - S DRIER — Nalo
Start 200 gr. 200 gr. 200 gr.
3 days later 218 gr. 213 gr. 209 gr.

From these figures, one can see that the DRIER — CalO
picked up from the air twice as much water as the DRIER —
N810.

A sample of 100 grams of shelled corn at 20% H.C.W.B.
was mixed with each drier under consideration in order to
'make the following nuns: xxx - 3 NalO, m - 3 CalO, and
‘ nIx - 3 s. The bottles filled with these ms were kept
in a temperature-control chamber at 80°F. The measurements
were taken as in the Experiment II and are shown in Table lh
and illustrated in Figure 12.

Table 14 shows that the minimum moisture content
reached at the end or six days was 1h.66% in MIX - 3 NalO
(a), and the maximum 16.89% in NIX - 3 S (a). At the end
of the same period of time the moisture content in MIX -

3 Calo (a) was 15.53%. Mold growth was observed in MIX —
3 CalO (e) at the end of 15 days and in tux - 3 s (a) at

the end of six days.

-88-

-89_

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:2 mgm<a

MOISTURE CONTENT(PERCENT WET BASISI

 

 

0—0 MIX-33 - 0 "

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I9 H MIX-SCOIO —O
A—A MIX-SNOIO —b
I8 \\ H MIX-SNOIO —0
I7 k
I6 1- T 1
‘7“ 1+2-
'5 k
~\1
I4 ‘” “
I3 —
I2
II
0 I 2 3 4 5 8 7 8 9 IO
TIME- (DAYS)

 

FIG.I2 -MOISTURE CONTENT OF WET SHELLED CORN WHEN
STORED WITH MlX-38,MIX-3NOIO, AND MlX-BCOIO.

 

 

"O-AFTER PREPARING THE DRIERS THEY WERE LEFT FOR 3 DAYS SPREAD OUT
ON A TABLE. (AT ROOM TEMPERATURE)

 

b-THE DRIER-3NOIO WAS DRIED AT ROOM TEMPERATURE.

 

-91-

At the same time, a similar trial was prepared with
DRIER - Nalo in the following way: the DRIER - NalO was
prepared and dried at reom.temperature for 48 hours, and
at the end of this time its moisture content was 5%. MIX -
3 N010 (b) was then prepared under the same conditions as
before (See Table 1a and Figure 12).

Table 14 and Figure 12 show that the moisture content
reached in MIX - 3 Halo (b) and nix - 3 NalO (a) are
practically the same. From this experiment (Table 13 and
13A) the author concludes that there is no great difference
between MIX - 3 N810 and NIX - 3 Halo (a) or MIX - 3 NalO
(b). However, there is a great difference between NIX -

3 CalO and MIX - 3 Oslo (a). Therefore, he also concludes
that DRIER - NalO 18 better than DRIER - Calo for the
following reasons:

1) To obtain the DRIER - Nalo it is not necessary
to use artificial drying as in obtaining DRIER - Calo.

2) The DRIER - NalO is therefore easier to make than
the DRIER - Oslo and also less expensive.

_ 3) 'The DRIER - NalO obtained without using artificial
drying is good enough to be mixed with shelled corn at
20% M,C;W.B. and to bring down its moisture content to
the limit for safe storage of shelled corn.

Iv. EXPERIMENT ON A LARGE SCALE WITH DRIER - NalO)

In this phase, the DRIER - Nalo was prepared as des-
cribed in "materials and methods." The only modification
made was in the quality of the sodium.chloride. Instead of
using table salt, "rock salt" was used. (Rock salt is
unpurified salt, as removed from salt mines.)

The containers used were 3 metal cylindrical bins
with the following dimensions: diameter - 11 inches,
height - 60 inches.

Three samples of shelled corn at 22.3% H~C.U.B. weigh-
ing 60 pounds each were mixed with the DRIER in order to
make: MIX - 3 NalO. The bins were covered as follows:

The bin.was sealed with a plastic sheet.

Bin (a)
Bin (b) - The tap of the MIX - 3 Nalo was covered
‘ with four inches of DRIER - NalO.

Bin (c) The tap of the MIX - 3 Nalo was left Opened.

(The bins were kept in a room.with a great variation
of temperature.)

Some phases of this experiment as the quantity of
salt, quantity of dried sawdust, and quantity of damp
shelled corn used are shown in Figure llB as the mixing
of salt solution with sawdust in Figure 11C. The Opera-
tions of filling the bin and screening the corn from MIX -
3 Halo are shown in Figures 11D and 11F.

-92-

-93-

The corn was screened from the MIX and weighed at
intervals of 1, 2, u, 6, 8, and 10 days. (See Table 15)
The data from Table 15 are illustrated in Figure in.

Table 15 shows that the minimumwmoisture content reached
at the end of six days was 13.25% in bin (c). Nevertheless,
at the end of ten days the moisture content was computed
again and there was no difference between the bin (a) and
the bin (b). At the same time, a sample of corn from the
three bins was taken and the moisture content determined
by using the oven method, and as Table 15 shows, the mois-
ture content as computed or determined was practically the
sale.

Mold growth was observed in all of these two months
later. The degree of mold was not marked but this result
leads to the conclusion that after ten days (maximum) the
corn should be screened from the mix and kept clean, or
mixed with a small amount of dry drier.

From this experiment the author also concludes that
to dry wet shelled corn with the use of DRIER - Halo, it is
not necessary to have the bin with the mix sealed when
the top is covered with four inches of the DRIER. Another
conclusion is that rock salt is somewhat more effective
than table salt to dry shelled corn.

The relative volumes of corn grain plus DRIER before
and after mixing are of some interest. An example is
given below for MIX - 3 NalO:

-911-

900 grams of shelled corn (20% M.C.W.B.) = llIOO ml

300 grams of DRIER - Nalo - 1350 ml
The total volume is 2,750 ml before mixing and 2,000 ml
after mixing. From this result, one can see that it is
not necessary to weigh the corn or the DRIER, because they
have practically the same volume. (See Figures 13A, 133,
and 113) So, to dry damp 'shelled corn (moisture content
equal to or less than 22.5%). he advises'one volume of corn
to one volume of DRIER; with wetter corn more DRIER should
be used.

Relative volumes of salt and sawdust used to make
DRIER Nalo were: Salt 1.9 cc and Sawdust _1_gg cc, or a
prOportion of about _1_ to 52 by volume.

A sample of corn from bin (b) was analysed after two
months and the amount of salt which was held by the corn-
grain was 0.05%.

 

Figure 13A - Relative volumes of DRIER — NalO
to damp corn.

 

Figure 13B — Weight and volume of MIX — 3 NalO.

 

Figure 13C — The author showing to Dr. C.w. Hall
(his minor professor) the G. Weevils in mixture
with DRIER.

-96-

TABLE 15

The drying of shelled corn (22.5% H.C.W.B.) in bins (as
designated) when conditioned with MIX - 3 Na10 (using rock
salt as sodium chloride in DRIER Nalo) and under a great
variation of temperature.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TIME WEIGHT MOISTURE WEIGHT MOISTURE HEIGHT MOISTURE
nus P8333133 cougENT ngggs cougsn'r ngggs cougsm
- fgm (a) fan: (b) *ijIN (G)

0 60.00 22.50 60.00 22.50 60.00 22.50

1 455.50 15.u6 51.20 14.68 51.00 19.112
2 5u.50 Iu.68 5n.00 13.89 56.50 17.68

h 54.30 14.37 53.80 13.57 55.70 16.52

6 5h.00 13.89 53:50 13.25 55.50 15.46

8 53.80 13.57 53.50 13.09 55.00 15.uo #
10 53.50 13.09 53.50 13.09 5u.50 14.68
10 ¥::--- #13.50 ----- #13.60 ' ----- #'1u.75

*:g:: (g : 3%: 2331:? :fizhnixp}a§t§§13h3§§ covered with h inches

**’Bin (0) - The top of the MIX - 3 Halo was left open.

of DRIER - Na10

#loisture content determined in oven.

MOISTURE CONTENT(PERCENT WET BASIS}.

 

2’;

22

2|

-97..

 

 

 

 

 

 

 

 

\\ 0—0- 4" LAYER ON TOP-
- IN.
\ I SEALED s

 

 

 

 

\ \

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

fi

\ K A;

 

 

 

 

 

 

 

 

 

 

 

 

TIME - (DAYS)
FIG. :4 — MOISTURE CONTENT OF WET SHELLED OORN WHEN
STORED IN OPENED BIN, SEALED BIN, AND IN A BIN WITH

4" LAYER 0F SAWDUST-SALT ON THE TOP. MIXED WITH
. SAWDUST AND SODIUM CHLORIOEmacI).

V. EXPERIMENTS WITH GRANARY HEEVIL

Nine samples of shelled corn at 20% M.C.W.B.'weighing

' 100 grams each were mixed with DRIERS to make the following
MIXES: NIX - 1 Halo, qu — 3 Na10, NIX - 5 Na10, MIX - 1
Ca10, NIX - 3 Oslo, MIX - 5 Ca10, nIx — 1 S, 141x - 3 S, and

MIX-5S.

At the same time, when the bottles were being

filled, 50 granary weevils (adults) were put inside the

containers.

For illustration see Figure 15E.

~A bottle

with 100 grams of shelled corn was left with 50 insects as

a check. All the containers were kept at room temperature

(average temperature of five weeks was approximately 80°F).

At the end of five weeks, the MIXES were screened

and the insects counted.

TABLE 15

Table 16 shows the results.

Behavior of granary weevil when in mixture with MIXES below.

 

 

 

 

 

 

 

 

 

 

 

 

RATIO BY
MIX VOLUME OF INSECTS INSECTS INCREASE OF
CORN T0 DEAD ALIVE ,POPULATION
DRIER _
NIX - 1 N810 1 : 3 no 10 0
MIX - 3‘N310 1 :1 10 “O 0
MIX - 5 N210 5 : 2 9 41 0
"IX - 1 0810 1 : 3 45 5 0
MIX - 3 0810 1 : 1 11 39 O
MIX-508.10 5:2 10 (40 O
max“; 1 s- 1 : 3 35 15 0
MIX - 3 S 1 : 1 8' 42 0
MIX - 5 S 5 z 2 7 “3 0
CHECK ----- 0 75 25

 

 

 

 

 

-98-

 

-99-

In the bottles where the volume of DRIER was greater
than the volume of the corn, the insects did not generally
stay in the mixture. At least 80% climbed to the top of
the MIX, trying to leave the containers, and most of these
eventually died.

Table 16 shows that when the granary weevil was in
mixture with corn and DRIER for a period of five weeks, at
least seven insects out of fifty were dead. Other conclu—
sions from.this experiment are: a) In spite of the fact
that five weeks are adequate to allow reproduction, there
was no cycle of life except when the granary weevil was
in plain corn. b) The effects of DRIER - NalO and DRIER -
CalO in comparison with DRIER - S on the insects were
almost identical, leading to the conclusion that the
insecticidal effect was largely due to the sawdust.

Seven additional experiments were set up based on the
fact that the insects climbed to the top of the MIX when
the amount of DRIER.was increased. (See Figures 15A, 15B,
150, 15D, 15F, 150, and 158). In each of the experiments,
all of the DRIERS mentioned were used. In Figure 15F, the
DRIERS were mixed as MIX - 3 NalO, MIX - 3 CalO, and MIX -
3 S and were covered additionally with one inch of each
respective DRIER. The methods and results are illustrated
in the figures mentioned.

The figures show that in none of the trials, the
insects went to the bottom of the container and in all of

-100-

the trials, they died except in Figures 15B, 15D, and 15H.
In Figure 15H, the insects left the bottle.

The main conclusion from this experiment was that the
insects died when the air for their respiration was passed
through the sawdust, and they were in contact with the
DRIER (See Figures 15A, 150, 15F, and 15G) supporting the
point that the sawdust used had some volatile substance
which killed the granary weevil if they were unable to
excape.

To prove this statement, the author set up the experi-
ment as shown in Figure 16. An Erlenmeyer suction flask
was used to supply fresh air to the insects and to avoid
air‘which passed through sawdust. Forty-six insects out
of 50 stayed at.the bottom of the flask and did not die
during a period of three weeks. The four that climbed to
the top (after 2h hours) died within a week.

When the direction of the air was reversed, in another
trial, so that all air must pass through sawdust, all
insects climbed to the top and eventually died.

 

Figure 130 shows the kind of bottles used in the
experiments with the granary weevil.

—lOl—

BOTTLE

$297 V7 ‘55

 

A
A

 

 

A.-(THE INSECTS WERE DEAD
AFTER 0 DAYS)

AVAVAVAVAVAVA
AVAV v v v A
AFTER IO MINUTES

FIG.l5A-MOVEMENT 0F G.WEEVIL IN "DRIER'l CORN ENVIRONMENT.

AVAvAVAVziVAVA
A v VAV v v VA

 

8
START

 

e,-(THE INSECTS DID NOT DIE)

AE TEB 8 HIE!!! E3

FIG.I58- MOVEMENT 0F G.WEEV|L IN "DRIER" ENVIRONMENT.

 

 

fl —DRIER- (3 INCHES LAYER)

VAV—CORN- (I INCH LAYER)
'0‘: — GRANARY wEEVILISOINSECTS)

 

 

 

~102—

Cl-(THE INSECTS WERE DEAD
AFTER 5 DAYS)

BOTTLE

  

AVAVAVA VA
VAVAVAVAVA VA 6'

START AFTER 2 MINUTES
FIG.I5C- BEHAVIOR OF G.WEEV|L IN CONTACT WITH "DRIER".

 

D-(THE INSECTS DID
NOT DIE)

AVAVAVAVA

VAVAVAVAVA

   

 

FIG.I5D- BEHAVIOR OF GWEEVIL IN CONTACT WITH CORN.
Mfg) —DRIER- (3INCHES LAYER)

 

AVA —coRN- (I INCH LAYER)
1. -.-.'II — “5295', _VYEEY'EQQJNSFCTS’

—103-

El- (SOME OF THE INSECTS WERE
DEAD — THE REST OF THEM
DID NOT REPRODUCEJ

BOTTLE

 

START

 

AFTER 5 WEEKS

FIG. I5E-BEHAVIOR 0F G.WEEVIL IN MIXTURE WITH "DRIER" AND CORN

71- (THE INSECTS WERE DEAD
AFTER 3 DAYS-I

   

 

Fl
FIG.|5F - MOVEMENT OF G.WEEVIL

IN MIXTURE WITH "DRIER" AND CORN.
% — DRIER —(60 GRI-“I INCH LAYER -

AVA -C0RN -(200 GR)
:3.

—GRANARY WEEV|L(50 INSECTSI

 

—lou-

Gl—(THE INSECTS WERE DEAD
AFTER SDAVSI

BOTTLE

 

5)

START AFTER 8 MINUTES

FIG.ISG— MOVEMENT 0F G.WEEVIL IN "DRIER".

H| -(THE INSECTS LEFT
THE BOTTLE.)

VVVVVA
H

VAVAVAVAVA
VA V

"I

   

FIG.I5H-MOVEMENT 0F G.WEEVIL: IN_"_D_RIER3CORN ENVIRONMENT

 

 

% —DRIER — ( 3 INCHES LAYER)

AVA —CORN —( I INCH LAYER)
0:0... —GRANARY WEEVILISOINSECTSI

 

 

 

-105-

SOURCE OF AIR.

 
 
 
 
  
  
 
   
   
 

GLASS TUBE.

RUB BE R STOPPER.

 

AIR.
If
n .W VIL .
3 0 EE
CORN.
SAWDUST.

 

i

  
   
  
 

 

  
  
   
 

   

I

AVA
VAKZAVA
VAVAVA

AVAV <7 <7
AVAVA Av

VAVAWAVAWA

FIG.I6-— BEHAVIOR OF ORANARY WEEVIL IN SAWDUST-CORN
ENVIRONMENT WHEN A SOURCE OF AIR IS SUPPLIED.

  

   

DISCUSSION OF THE THEORY OF DRYING SHELLED CORN USING A
‘flI2TURE‘OR‘SIWDUST'IND'SIET’TDRIER)

To explain the phenomena which take place in drying

 

shelled corn with a "DRIER," corn at 20% NiC.W.B.*when in
mixture with the DRIER — Nalo was chosen as a good
representative example.

As the sawdust becomes damp when in mixture with damp
corn, the following processes or methods of movement of
water from corn to sawdust occur: (a) Capillary action -
which causes the free water of damp corn to flow through
sawdust, (b) Differences in vapor pressure between damp
corn and dried salted sawdust. It is considered that (b)
is usually the major drying effect.

The water which is held by the damp shelled corn when
in a NIX will move mainly in the form of water vapor. This
will be taken up, at first, mainly by the sawdust, because
of its low vapor pressure. At the same time, however, some
water is absorbed by the sodium.chloride and the relative
humidity due to the conversion of dry salt to a saturated
solution will be 75%. After the sawdust reaches equilibrium
‘at 75% R.H., further solution of salt will maintain
approximately 75% R.H. until the salt becomes dissolved.

To saturate 100 grams of water, the weight of sodium
chloride required at 80°F. (temperature at which the MIXES
were kept) is 36 grams (12). This means that 36 grams of

sodium chloride can hold 100 grams of water in a saturated
-106-

-107-

solution at a vapor pressure only 75% that of ordinary water.
The relative humidity from the time when the salt absorbs
the first drop of water until all 100 grams are absorbed is
75%. This amount is 100/36 orrU2.75 grams of water/gram

of RaCl. '

The equilibrium moisture content (wet basis.) of saw-
dust at 80°F. and 75% relative humidity (See Figure 8) is
12.5%» Thus, if we have 100 grams of dried sawdust and
submit it to these conditions, it will absorb 12.5 grams
of water.

From these figures, the theoretical capacity of
absorbing water of 100 grams of DRIER - NalO (90.9 grams
of dried sawdust and 9.09 grams of sodium chloride) may
be computed to be 36.61 gramp (11.36 grams by the sawdust)
plus 25.25 grams by the salt) ) (See Table 17). This
capacity is when the DRIER - Na10 is in equilibrium at 80°F.
and 75% relative humidity. Nevertheless, the theoretical
capacity of the DRIER for absorbing water under other
temperatures will be practically the same. (See Figure 9).

With the data from Table 13 and Table 17, the author
made the Thble 18, which shows (1) the actual water uptake
from 100 grams of shelled corn at 20% N.C.H.B., (2) the
actual quantity of water taken up by 1 gram of the DRIER,
(3) The percentage of the theoretical drying capacity of
DRIER - NalO.

—108-

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-109-

In all of the MIXES, except MIX - 10 NalO, one can see
by comparing Table 18 with Table 17, that there was an
extra quantity of DRIER which was not used. This is due
to the fact that once the equilibriumImoisture content of
shelled corn was reached its drying process stopped.
Nevertheless, with an excess of DRIER, as in MIX 1 Nalo, the
corn reached a moisture content of 12.24%, where the
relative humidity was below 75%» In this case, little, if
any, salt dissolved, all being absorbed by the sawdust. In
NIX - 3 NalO and MIX -' 5 NalO, the corn reached its
equilibrium which is in the region of 111% at 80°F. and
75% relative humidity. Considerable salt was still
undissolved. '

At last the corn in MIX - 8 NalO and MIX - 10 NalO
reached a moisture content greater than 16% proving that
the relative humidity in these cases was above 75% due
to scarcity of DRIER. All or most of the salt was
dissolved, and the solution became less than saturated.

Table 18 shows that where the quantity of DRIER to
dry the same amount of corn was decreased its uptake of
water was greater per gram of DRIER. For example, in
MIX - 3 NalO only Sufi of the drying capacity of the DRIER -
Nalo in picking up moisture from corn was uSed, and_in
MIX - 5 N810 83%. The author concludes that when the
drying capacity used is greater than 83% or smaller than

-110—

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-111-

511% the amount of DRIER used is in scarcity and excess
respectively. Thus, the DRIER - Halo in MIX - 3 NalO
easily met the requirements for safe storage of shelled
corn.

From the computations, it is shown that the DRIER -
Halo absorbed more than 20% of its weight of water in
reducing the moisture content of shelled corn from 20% to
111%.. Similarly, DR’IER - Nalo (having "rock salt " as
sodium chloride) dried at room temperature, when in
MIX - 3 mm with shelled corn at 22.5% H.C.U.B. absorbed
water to about 30% of its weight in reducing the moisture
content or shelled corn from 22.5% to 13.5%.

SUMMARY AND CONCLUSIONS

I. DRYING SHELLED coax BY USING A swr — sawnus'r MIXTURE

1. Corn that was too damp for safe storage was dried
sufficiently for short periods of safe storage by mixing
with it a sufficient amount of a "DRIER" composed of sawdust
dried after being dampened with a solution of sodium
chloride, or calcium chloride. To prepare the solution a
«13111: of water about 35% of that of the sawdust is needed.

2. The proportion of 10 parts of dry sawdust to 1
part of dry salt (by weight) is recommended, prepared as
above.“ -

3. For moisture contents up to about 22.5 - 25% in
the corn a proportion of 3 parts of corn, by weight, to 1
part of DRIER was adequate, i.e., NIX - 3 Halo, or MIX - 3
Calo. This prOportion can be attained also by using equal
volumes of corn and DRIER.

it. Although calcium chloride had some advantages in
a DRIER, the use of sodium chloride seems preferable because
it could be prepared by air-drying the impregnated sawdust,
whereas a calcium chloride DRIER required oven drying, and,
even then required protection to avoid excessive uptake of
moisture from somewhat damp air.' For longer storage,
additional water may be removed with sawdust treated with
CaClz. .

5. "Rock salt" was as satisfactory as was purified

"table salt," and somewhat more effective.

-112-

~113-

6. Depending upon the proportion of salts to sawdust,
DRIER to corn, the moisture content in the corn, the
relative humidity at final equilibrium, the amount of
water absorbed from.the damp corn may vary widely, from a
few percent up to almost 100% of the weight of the DRIER.

7. Screening the sawdust through a l2/6h inch round
screen before preparation of the "DRIER", made possible the
easy separation of the corn on l/h inch square hole screen
when drying was completed.

8. Screening to remove the damp sawdust should be
done after about 10 days and not longer than a month, to
permit examination, mixing, and the decision in regard to
the need for further drying. If the sawdust is obviously
very damp after a day or two, one may screen and start
afresh with additional DRIER. '

9. Comparing the drying of‘shelled corn at 20% M;C.W.B.
using the DRIER - Nalo with the drying of the same grain
using unheated air (See review of literature), the following
advantages in using the first method can be listed:

a) Drying shelled corn with DRIER - Nalo (rock
salt) is cheaper than when drying it using unheated air.

b) The drying of shelled corn by using the DRIER
does not depend upon the weather after laying the MIX inside
the bin. HOwever, using unheated air to dry it, the

weather is a crucial factor.

~114-

c) To dry shelled corn at 20% MoC.W.B. for a
period of ten days to one month mold growth does not take
place, but using unheated air under unfavorable conditions
(as the climate of Brazil), the shelled corn will not dry
in a period of time safe against mold growth and consequently
spoilage will take place.

10. The final moisture content of the corn properly
dried with salted sawdust,varied from about l3-lh.5%»M.C.W.B.
depending upon the conditions.

‘ II. THE INSECTICIDAL EFFECT or THE DRIER (MIXTURE or
""‘1flflnnnhr1uurInnmfiflnrlxnunuurlnfinnu;

 

In the experiments conducted with granary weevils as
shown in Figures 15A, 153,150, 15D, 15E, 15F, 150, and 15B,
the following conclusions were made:

1) The insects when in MIXTURE as illustrated in
Figure 15E did not reproduce and a certain proportion died.
This proportion increased when the volume of the DRIER.was
increased in prOportion to the volume of corn (See Table 16).

2) The repellant and insecticidal effect of the DRIER
on the insects was proven when: (a) the insects climbed to
the tap of the MIX trying to leave the container. (b) the
insects left the container, and (c) when they eventually
died if they were not allowed to leave the container (See
Figures 15A, 150, 15F, 150, and 15B). '

3) The insects in all of the trials never went to the
bottom.of the container (all of the figures illustrate this
fact), leading to the conclusion that to avoid granary
weevils in storage of shelled corn a good means is to use
a layer of the DRIER at the top of the corn mass.

A) The sawdust had some volatile substance(s) in it
which was (were) fatal to the granary weevils. This
statement is supported by the experiment conducted as

illustrated in Figure 15.

-115-

SUGGESTIONS FOR FURTHER STUDY
1. Drying to about 12.5% 11.0 .W.B. rather than 14.5% (65vs.
73% R.B.) would be helpful for longer storage. How may this
be done using a Neel base?
2. Instead of preparing an.aqueous solution of sodium
chloride to mix with sawdust to make DRIER - Nalo to use
colloidal salt and to compare their effectiveness. Dexter
(unpublished) has shown that this can be done.
3. To fill a bin with dried shelled corn (having a moisture
content from 13 to lu%) and at the top of the corn to use
a layer of four inches of DRIER - Halo and to verify the
capacity of the DRIER in avoiding moisture accumlation at
the top and eventually mold growth.
a. To use the DRIER - NalO in drying coffee due to the
fact that coffee is the main crOp of Brazil.
5. In regions where sawdust is not available to try other
absorbent materials as: ground corn cob ,‘coffee straw, etc.
6. To use sawdust from.ceveral different kinds of wood in
preparing DRIERS to study the behavior of the granary
weevil with only one specified quality of wood. At the
same time, it would be advisable to use other species of
insects which attack the grain when in storage.

I

-116-

1.

2.

3.

h.

5.

6.

7.

8.

9.

10.

11.

12.

LITERATURE CITED

Allison, F. E., The Use of Sawdust for Mulches and Soil
Improvement, Circular No. 891, U;S.D.A., Nov. ~

1951.

Anderson, J. A., Alcock, A. W., Stora e of Cereal Grains
and Their Products, American AssocIatIon o?
CereaI Chemists. St. Paul, Minnesota. 195a.

-------- , Anuario Estatistico Do Brazil - I.B.G.E. -
Conselfio Nacional DefEstatIstlca, 1960.

-------- , Atlas Do Brazil, Conselho Nacional De
GeogrEfia, R. J., Brazil, 1959.

-------- , Brazilian Technical Studies, Institute of
IntefiamerIcan ITfaIrs. FBreign Operation
Administration, Washington, D.C., 1953.

Cotton, R. T., Pests of Stored Grain and Grain Products,
Burgess Publishing Company, fiinneapolis, Hinn.,
195 .

Dexter, S. T.. and Creighton, J.W., A Hethod for Curing
Farm Products by the use of Drying Agents.JOurn.

American Societ of A rono , Vol 90, No. 1,
p. ?O-79, Jan. 1958. GEneva, New York.
Dexter, SEAT., Congittoning Popcorn to the Proper
isture on ent for Best Popping, Michigan

A ricultural E eriment-Station Quar erl
figlletin,lrtic§e 26-8, p. 63569, RSV. 19*6.
Dexter, S. T., The vapor Pressure or Relative Humidity

Approach to Moisture - Testing for Safe Storage

of Harvested Crops. Aggonogy Journal, Vbl.h7,
No. 6, p.267-270, June, 1955.

Dricot, C., Bruggenaus, R. J., and Dufey, V., Drying
Combine — Harvested Grain, National Institute

of Agricultural E ineerin (Gr. Brit.),
TTanslatIonNo. E, 1951.
Foster, G. E., Stahl, B. E., and others, Aerations of

Grain in Commercial Storages. U S ricultural
Marketing Res. Report 118,h6 pp., 1365

 

Hall, Carl W., Dr in Farm.Cro s, Edwards Brothers, Inc.,
Ann Ar or, ichigan, 1957.

-117-

—118-
13. Hall, Carl W., Calcium.Chloride for Moisture Absorption

in Corn Storage, Michigan Aggicultural ggfieri-
ment Static Quar er 1e in, o . , o. ,
p. 561-567. FeBruary I958.

1h. Holman, L. E., Aeration of Stored Grain ricultural
Engineering, Vol. 36, p. 667-668, Eatofier 1955.
15. Hurst, M. W., and Humphries, R. W., An Absorptive
Agent for Drying Grain. Ag§icultural Engineering,
'Vol. 17, p. 62, February 9 -
16. ------ , International Critical Tables, v61. 3, p 365.
raw— 0 ompany.

17. Johnson, H. R., Cooling Stored Grain by Aeration

Aggicultural Engineering, Vol. 38, p. 238-2u1,
Pr .

18. Kaufmann, Dale W., Sodium Chloride, The Production and
Pr erties of Salt and Brine. IfiErIcan Chemical
Socgety, Monograph series No. 145, Reinhold
Publishing Corporation, New York; Chapman and
Hall, Ltd., London, 1960.

19. Metcalf, L. C., and Fling, P. W., Dest ctive and
Useful Insects Their Habits and Control),
raw- 0 ompany, nc., ew or and
London. 1939.

20. Panshin, .A..J., Lumber Dry Kilns and Their Operation,
Michigan ggricultural Egperiment Station,
section 0 ores r ,ggpec a e n o. 359,
June 1M9 .

21. Rasmssen, Edmnd F., Dry Kiln, Operator's Manual,
Agriculture Handbook No. 188, U.S.D.A., Forest

Service,MarchOI§61.
22. Robertson,I. M., Swath Harvesting: The Process of

Drying, Journal of éggicultural Engineering
Research, p. - , 56}

23. Robinson, R. N., Hukill, W. J., and Foster, G. H.,
Mechanical ventilation of Stored Grain

A icultural E ineerin , Vol. 3h, p.681-68fl,
Oggofier 1955.

 

 

 

2h.

25.

-119-

Stahl, B. M., Grain Bin Requirements. U.S.D.A.,
Circular No. 835, Washington, D. 5., 1950.

------ , Surve of the Brazilian Econo - 1960.
BFazI¥Ian Eifiassy, Washington, D. C.

ROOM USE cm

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