The Refractive Index, Molecular Refraction And Disp O f Some Phenol Derivatives II. A Universal Laboratory Amalgam Lamp ROGER CLA.iv. ProQuest Number: 10008486 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest ProQuest 10008486 Published by ProQuest LLC (2016). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 (r \ \ '■ I. The Refractive Index, Molecular Refraction And I>ispersion 11< O f Some Phenol Derivatives i \ II. A Universal Laboratory Amalgam Lamp 1,■(^■/ ;1 , " s , By ROGER CLARK DAWES A T H E S IS Submitted to the Faculty o f Michigan State College in P artial Fulfillment o f the Requirements fo r the Degree o f Doctor o f Philosophy KEDZIE CHEMICAL LABORATORY EAST LANSING, MICHIGAN 1936 I THE REFRACTIVE INDEX, MOLECULAR REFRACTION AND DISPERSION OF SOME PHENOL DERIVATIVES component elements modified by the manner of combination.0 This was the first def­ inite statement regarding the constitutive nature of refractivity. Gladstone and Dale confirmed the observations of Delffs and Berthelot, mentioned earlier, that the re­ fractivity of the homologs rises with in­ crease in their molecular weight. Landolt (Pogg. Ann., 125, 595 (1864)), showed that the molecular refractivity of isomeric fatty acids and esters was the same. Lan­ dolt found that with an homologous series the refractive index increased for each ad­ ditional CH2 but this increment decreased as the series ascended. The average value of this increase in refractivity as calcu­ lated from the Gladstone - Dale formula (n - 1/d = R fI, a constant) was found to be 7.6. Landolt employed the increment, 7.6, to calculate the value of the refractivity of carbon, oxygen and hydrogen from the empirical formulae of compounds. The cal­ culations were inaccurate as Landolt neg­ lected the constitutive influences in the molecules. About 1870 attention was turned to the constitutive influence on the refrac­ tive index. Gladstone (Trans. Chem. Soc., 23, 147 (1870)) found that the molecular refractivity of an unsaturated compound is greater than that calculated from the values for the elements, as found in the literature. Bruhl began his investigations about 1880. He calculated the refractivity of an element under different structural conditions. Bruhl obtained different values for hydroxy and carbonyl oxygen and later at the suggestion of Conrady (Zeit. Phys. Chem., 3, 210 (1889)) calculated a new value for the oxygen found in ethers and esters (Zeit. Phys. Chem., 7, 172 (1891)). Bruhl should receive the credit for the modern development of refractivity. Bruhl (Ber., 24, 286-96) improved the 1 0-3 CL/? wf The first experiments on refractive index were made by Biot and Arago (Mem, de l'Instit. de France, 7 501 (1806)). They found that the refractivity of gaseous com­ pounds was equal to the sum of the refractivities of the constituents in the gaseous state, Dulong (Ann. Chim, Phys., (S), SI , 154 (1826)) about twenty years later pub­ lished a series of very accurate measure­ ments which showed that the statement of Biot and Arago was only approximate. Biot and Arago worked with gases whose refractivities differed not far from unity and large errors in measurement were not apparent in the final results. Isomeric substances were first studied by Deville (Compt. rend., 11. 863 (1840)), and Becquerel and Cahours (Compt. rend., 11, 867 (1840)), who found that liquid isomeric esters of the same density had the same refractive index. Delffs (Pogg. Ann., 81, 470 (1850)) and Berthelot (Ann. Chim. Phys., (3) 48. 342 (1856)) examined a few homologous series. The work of Berthelot is espec­ ially noteworthy, since it was the first attempt to give a quantitative expression for the refractivity of a group. Berthelot found that in ascending homologous series the molecular refractivity increases. From his data he was able to calculate the in­ crease in the refractivity for the addition of a methylene group, This value was 18 units by the Laplace formula (Mecanique Celeste, (4) 10,237 (1805)). The Laplace formula is n 2 - l/d = R 1, wherein R 1 is a constant called specific refractivity. The work of earlier investigators led to the classical work of Gladstone and Dale (Phil. Trans., 153. 217 (1863)) and of Landolt (Pogg. Ann., 125, 595 (1864)). Gladstone and Dale obtained refractivity data from a number of isomeric compounds and they concluded that, nEvery liquid has a specific refractive energy composed of the specific refractive energies of the f ^ ( Vv\. , 2 THE REFRACTIVE INDEX technique of using the Pulfrich Refrac­ tometer to measure refractive indices at high temperatures. His excellent results on the refractive index of water (Ber., 2 4 , 644-49) were used as a guide in the develop­ ment of technique in this investigation. Although several other investigators measured the refractive indices of organic compounds at different temperatures, the first accurate investigation was the re­ search of Perkin (J. Chem. Soc., 61, 287 (1892)), Falk (J. Am. Chem. Soc., 51. 86-107; and 806-21 (1909)), shows the vari­ ation of the refractive index of a compound with changes in temperature. The graphs are straight lines, within the range of experimental errors, for temperatures rang­ ing from 10 to 80° C. The Pulfrich Refractometer was in­ vented by Carl Pulfrich in 1895. Pulfrich's description is found in the Zeitschrift Physikalische Chemie, 18, 294-99 (1895). Still further details concerning its operation are to be found in an article by C. Cheneveau (Ann. Chim. Phys., (8 ) 12. 145). APPARATUS AND MATERIALS Light Sources: An amalgam lamp of the Cenco Laboratory Mercury Arc type; an alternating current laboratory arc of a design described in Part II of this thesis; a Hydrogen Gas Vapor Lamp; a General Elec­ tric Sodium Vapor Lab Arc for use on al­ ternating current; and a Wratten Filter #24 to cut out the light below 5790^. Refractometer: Zeiss Pulfrich Re­ fractometer Nr, 33959, including five prisms and one cooling coil for temperature con­ trol. Constant Temperature Bath: A tenliter glass aquaria fitted with an eightbladed stirrer attached to a water motor and having four* thermo-regulators set at 35° C; 25° C; 20° C; and 15° C. Two 125 Watt, 110 Volt A.C., knife type heaters were regulated by a dry cell relay. A Bureau of Standards calibrated thermome­ ter, No. 49571 was employed for tempera­ ture measurements. Using this thermometer the above temperatures were found to be 34.98° C; 25.08° C; 19.96° C; and 15.00° C. The water flowed by gravity from the constant temperature bath through the Pulfrich Refractometer. It was then re­ turned to the bath by an ingenious device (D.H. Cameron, Ind. Eng. Chem., June 1925). This was a vacuum pump arrangement running off of an ordinary water aspirator. Pycnometers: These were small bulbs of about 1 cc. capacity blown on the end of a very fine capillary. These pyc­ nometers were very accurately calibrated at the temperature used, with mercury of a very pure grade. Only one temperature was used because of the small amount of mate­ rials available for use. Organic Chemicals: These were ob­ tained from Dr. R. C. Huston and were those carefully prepared by his students, many times redistilled and sealed in tubes where they were kept in the dark until ready for use. The compounds measured were: 6 - Bromo, o - Cresol; 2 - Bromo, 6 - Methyl Phe­ nol; 2 - 6 Dibenzyl, p - Cresol; o - Bromo Phenyl, Benzyl Ether; 2 - Bromo, 6 - Ben­ zyl Phenol; 2 - Bromo, 4 - Benzyl Phenol; Methyl Ether of 2 - Bromo, 6 - Benzyl Phenol; Ethyl Ether of 2 - Bromo, 6 - Ben­ zyl Phenol; Phenyl Benzyl Ether; 1 - Phenyl Butyl, Phenyl Ether; 2 - Bromo Phenol; p 3 Chloro Benzyl Phenol (C); p - 3 Chloro Benzyl Phenol (A); p - 3 Chloro Benzyl Phe­ nol; and Dibenzyl Phenol. Tables: The refractive index was calculated for the Cadmium 6439 A; Mercury 5790 A. 5770 A, and 4358 A for Prisms I and IV and added to the tables furnished by the Zeiss Company. For Prisms IIe and Ve the tables furnished by the manufacturer, were the only ones used. At least one cal­ culation was carried through in its entire­ ty for each compound. This method of ob­ taining the refractive index will be dis­ cussed in a later part. EXPERIMENTAL PROCEDURE In order to develop the proper technique in the use of the refractometer many runs were made using substances for which values of the refractive index could be found in the literature. Chief among these were water, absolute ethyl alcohol, benzene and ethyl cinnamate. These were measured at the four different tempera­ tures and for the eight wave lengths of light employed. Repeated trials gave val­ ues of the refractive index that agreed ROGER CLARK DAWES within place. sitive dex to place. agreed place. a few units in the fifth decimal The Pulfrich Refractometer is sen­ to variations in the refractive in­ one unit in the fourth decimal The calibration measurements to five units in the fifth decimal The first step in the procedure was to learn the proper technique to employ in the use of the refractometer. The tech­ nique outlined by M. C. Cheneveau (Ann. Chim. Phys., (8 ) 12, 384 (1907)) and Daniels, Mathews and Williams (Experimental Physical Chemistry, McGraw-Hill, New York (1934), 40-42 and 332) was followed. The principle of operation of the Pulfrich Re­ fractometer is the application of the graz­ ing angle at the surface of the liquid in the small cup fastened to the prism. The refracted light is then brought into focus upon cross hairs, provided in a telescope mounted upon a circular scale. The read­ ings on the scale are degrees of deflec­ tion and are converted into the refractive index by making use of the formula: n = N 2 - sin2 i wherein, n — refractive index of liquid for wave length, N = refractive index of prism for wave length and i = angle read off scale of telescope. The tables give the value of (n) for (irs) of many values and for several wave lengths. For aqueous solutions the cup was cemented to the prism with Canada Balsam. However when an organic substance was placed in the cup a cement made of a sat­ urated gelatin solution containing a trace of potassium dichromate was employed. Assuming that the refractometer is set up with Prism Ie mounted firmly upon the base and the cooling coil connected with the constant temperature bath, let us make a measurement of the refractive index of a compound. Let the compound be 6 Bromo, o - Cresol and have a temperature of 25° C. About 1 ml. of the liquid was placed in the cell on the prism. A period of at least fifteen minutes was allowed in order that the temperature of the liquid should reach that of the constant tempera­ ture water flowing through the cooling coil. The light source was placed 1/2 meter from the condensing lens of the re­ 3 fractometer. The notched shutter was closed until the lines that appeared in the field of view of the telescope were sharply outlined. The cross hairs were placed tan­ gent to the desired line and on the side of least refraction. The value of the angle (i) was then read from the scale and re­ corded, At the side of the eyepiece is a small window having a reflecting prism ce­ mented to it. Light passing through this window is reflected to the prism face and back to the eyepiece of the telescope, giving two images of the cross hairs. When the two images of the cross hairs are made to coincide the zero point of the instru­ ment is determined. The zero point varies for each measurement and must be subtract­ ed from the angle (i) as read from the scale to give the corrected angle. Oppo­ site the corrected angle, the refractive index is found in the tables. It is very important that a good reading be obtained for the cadmium red line of wave length 6439 £, for this line is the one from which we hope to draw our conclusions for the refractive index of these compounds. This line has been adopt­ ed as the standard of length by physicists and the chemists should adopt it as their standard for this type of physical measure­ ment of a compound. EXPERIMENTAL RESULTS This section contains the values found for the refractive index, density at 25° C, molecular refractions for the sodium D and the Cadmium red lines, the change per degree in the refractive index for each wave length and the dispersions for the compounds employed. The values given are the averages of ten trials for each temperature and wave length. The molecular refraction, change per degree and dispersion were calculated using the aver­ age values as recorded. Also under this heading are includ­ ed thirty graphs showing the variation of the refractive index with changes in tem­ perature and in the wave length of light employed. The values for the various angles (i) are also given for the wave lengths 6563 £; 6439 I ; 5893 2; 5790 5770 A; 5461 A; 4861 A and 4358 A. 4 THE REFRACTIVE INDEX REFRACTIVE INDEX OF 6 - BROMO, o - CRESOL t 15 20 25 35 656 1.56242 1.56040 1.55759 1.55293 6439 1.56314 1.56132 1.55852 1.55238 5790 5770 1.56883 1.56702 1.56423 1.55801 5893 1.56771 1.56589 1.56313 1.55691 5461 1.57248 1.57065 1.56789 1.56206 4358 Absorbed Absorbed Absorbed Absorbed 486 1.58190 1.57975 1.57685 1.57207 DENSITY at 25° C = 1.4016 MOLECULAR REFRACTION 656 .0004747 6439 .0005381 D - C 0.00529 0.00549 0.00554 0.00398 CD i —i 0 0 .00453 2 t 15 656 ------ 6439 1.56584 1.56377 1.56154 1.55722 20 25 35 ----------- DISPERSION 486 - D 0.01419 0.01386 0.01372 0.01516 D - 6439 0 .00457 0 .00457 i Cadmium 6439 Obs. 43.04 Calc. 40.43 CHANGE PER DEGREE 5770 5893 5790 .0005409 .0005403 o o t 15 20 25 35 Sodium D 43. 33 Obs. 5461 .0005209 486 .0005517 4358 Absorb 4358 - 6439 Absorbed Absorbed Absorbed Absorbed 4358 - D Absorbed Absorbed Absorbed Absorbed REFRACTIVE INDEX OF BROMO, 6 METHYL PHENOL - - 5770 5790 1.57161 1.56947 1.56729 1.56294 5893 1.57046 1.56833 1.56608 1.56185 5461 1.57536 1.57317 1.57092 1.56660 486 ------- 4358 1.59641 1.59414 1.59190 1.58743 DENSITY at 25° C = 1.4227 Sodium D MOLECULAR REFRACTION 656 t 15 20 is5 r. 6439 .0004310 D - C Obs. CHANGE PER DEGREE 5790 5893 5770 .0004306 .0004334 D 6439 0.00462 0.00456 0.00454 0.00463 - Cadmium 6439 Obs. 42.59 Calc. 40.43 42.87 DISPERSION 486 D - ------ 486 .------ 5461 .0004383 4358 D 0.02595 0.02581 0.02582 0.02558 - 4358 .0004489 4358 - 6439 0.03057 0.03037 0.03036 0.03021 5 ROGER CLARK DAWES REFRACTIVE INDEX OF 2 - 6 DIBENZYL p - CRESOL _t _ 656 15----------SO 25 35 6459 -----1.60060 1.59882 1.59484 5893 -----1.60605 1.60409 1.60003 5790 5770 -----1.60759 1.60541 1.60125 5461 486 ----------1.61155---- -----1.60951---- -----1.60534---- ------ 4358 -----Absorbed Absorbed Absorbed DENSITY at 25° C = Sodium D Cadmium 6439 MOLECULAR REFRACTION 656 .------ 6439 .0003840 t D - C 15 20---------25---------- D - 6439 20 25 35 656 1.60270 1.60100 1.59884 1.59555 5461 .0004128 486 .------- DISPERSION 486 - D 4358 - D _ 0.00545-------------- ------ -------------0.00527------- ------ ------ -------------0.00519 ----------- - 55 t 15 CHANGE PER DEGREE 5790 5893 5770 .0004017 .0004091 6439 1.60398 1.60172 1.59964 1.59538 REFRACTIVE INDEX OF o - BROMO PHENYL, BENZYL ETHER 5790 5893 5770 5461 1.60923 1.61054 1.61465 1.60711 1.60838 1.61248 1.60614 1.60487 1.61025 1.60061 1.60183 1.60591 486 1.62486 1.62302 1.62086 1.61644 4358 Absorbed 4358 - 6439 ------------------------------------- 4358 1.62943 DENSITY at 25° C = 1.40025 MOLECULAR REFRACTION 656 .0003573 t 15 20 25 35 6439 .0004304 D - C 0.00653 0.00611 0.00603 0.00506 Obs. Sodium D 64.68 Calc. CHANGE PER DEGREE 5790 5893 5770 .0004308 .0004355 D - 6439 0.00525 0.00539 0.00523 0.00523 DISPERSION 486 - D 0.01563 0.01591 0.01599 0.01583 64.93 5461 .0004370 Cadmium 6439 Obs. 64.22 486 .0004213 4358 4358 - D 4358 - 6439 0.02882 0.03405 6 THE REFRACTIVE INDEX REFRACTIVE INDEX OF 2 - BROMO, 6 - BENZYL PHENOL t 15 20 25 35 656 1.60928 1.69743 1.60526 1.60100 DENSITY at 25 6439 1.60195 5790 5770 5893 1.61573 1.61379 1.61135 1.60728 5461 1.62124 1.61927 1.61679 1.61268 1.60853 C = 1.3876 Cadmium 6439 Obs. 65.54 Sodium D MOLECULAR REFRACTION 656 .0004141 15 20 25 35 4358 1.64572 1.64369 486 1.63178 1.62974 1.62765 1.62322 6439 D - C 0.00645 0.00636 0.00609 0.00628 Obs. Calc. 65.84 CHANGE PER DEGREE 5790 5770 5893 .0004228 5461 .0004281 DISPERSION 486 - D 0.01605 0.01595 0.01630 0.01594 D - 6439 0.00533 64.93 486 .0004282 4358 .0004064 4358 - 6439 4358 - D 0.02999 0.02990 REFRACTIVE INDEX OF 2 - BROMO, 4 - BENZYL PHENOL 15 20 25 35 656 1.61202 1.60970 1.60760 1.60327 DENSITY at 25 .6439 5790 5770 5893 1.61811 1.61622 1.61415 1.60996 5461 1.62370 1.62175 1.61966 1.61545 486 1.63479 1.63238 1.63014 1.62574 C = 1.3777 Sodium D MOLECULAR REFRACTION 656 .0004375 15 20 25 35 4358 1.64839 1.64634 1.64424 1.63983 6439 D - C 0.00609 0.00652 0.00655 0.00669 Obs. 66.55 CHANGE PER DEGREE 5790 5770 5893 .0004074 D - 6439 --------- DISPERSION 486 - D 0.01668 0.01616 0.01599 0.01578 Calc. 65.40 5461 .0005154 4358 - D 0.03028 0.03012 0.03009 0.02987 Cadmium 6439 Obs. None 486 .0004529 4358 .0004282 4358 - 6439 ---------- ROGER CLARK DAWES 7 REFRACTIVE INDEX OF METHYL ETHER OF 2 - BROMO, 6 - BENZYL PHENOL t 15 656 1.59383 1.59204 1.59004 1.58567 20 25 35 6439 1.59465 1.59276 1.59082 1.58597 5790 5770 1.60093 1.59902 1.59697 1.59293 5893 1.59968 1.59779 1.59575 1.59169 5461 1.60489 1.60295 1.60090 1.59683 486 1.61515 1.61320 1.61111 1.60656 4358 1.62774 1.62570 1.62356 1.61932 DENSITY at 25° C = 1.3290 Sodium D MOLECULAR REFRACTION 656 .0004080 t 15 Obs. 6439 .0004337 D - C 0.00585 0.00575 0.00571 0.00602 20 25 35 70 .90 CHANGE PER DEGREE 5790 5893 5770 .0003996 .0003999 DISPERSION 486 - D 0.01547 0.01541 0.01536 0.01487 D - 6439 0.00503 0.00503 0.00493 0.00572 Cadmium 6439 Obs. 70.42 Calc. 69. 53 5461 .0004029 486 .0004296 4358 - D 0.02806 0.02791 0.02781 0.02763 4358 .0004209 4358 - 6439 0.03309 0.03294 0.03274 0.03335 REFRACTIVE INDEX i OF ETHYL ETHER OF 2 - BROMO, 6 - BENZYL PHENOL t 15 20 25 35 656 1.58043 1.57857 1.57646 1.57224 6439 1.58114 1.57927 1.57724 1.57315 5790 5770 1.58715 1.58529 1.58320 1.57907 5893 1.58616 1.58412 1.58204 1.57792 5461 1.59097 1.58907 1.58695 1.58281 486 1.60068 1.59884 1.59655 1.59231 4358 1.61270 1.61081 1.60867 1.60434 DENSITY at 25° C = 1.2334 Sodium D MOLECULAR REFRACTION 656 .0004096 t 15 20 25 35 6439 .0003993 D - C 0.00573 0.00555 0.00558 0.00568 Obs. 80. 10 CHANGE PER DEGREE 5790 5893 5770 .0004038 .0004123 D - 6439 0.00502 0.00485 0.00480 0.00477 D ISPERSIQN 486 - D 0.01452 0.01472 0.01451 0.01439 Calc. 74.13 5461 .0004080 4358 - D 0.02662 0.02669 0.02663 0.02642 Cadmium 6439 Obs. 79.57 486 .0004187 4358 .0004225 4358 - 6439 0.03165 0.03154 0.03143 0.03119 8 THE REFRACTIVE INDEX REFRACTIVE INDEX OF PHENYL BENZYL ETHER t 15 20 25 35 656 1.59572 1.59380 1.59149 1.58714 6439 1.59670 1.59464 1.59244 1.58792 5790 5770 1.60309 1.60105 1.59881 1.59429 5893 1.60184 1.59975 1.59754 1.59303 5461 1.60726 1.60512 1.60287 1.59831 486 1.61760 1.61563 1.61316 1.60878 4358 1.63067 , 1.62857 1.62623 1.62143 DENSITY at 25° C = 1.3224 Cadmium 6439 Obs. 47.13 Sodium D MOLECULAR REFRACTION 656 .0004288 6439 .0004391 D - C 0. 00612 0 .00595 0.00605 0. 00589 t 15 20 25 35 Calc. 46.81 Obs. 47. 46 CHANGE PER DEGREE 5790 5893 5770 .0004403 .0004400 D - 6439 0.00514 0.00511 0.00510 0.00511 DISPERSION 486 - D 0.01576 0.01588 0.01562 0.01575 5461 .0004473 486 . .0004410 4358 - D 0.02883 0.02882 0.02869 0.02840 4358 .0004624 4358 - 6439 0.03397 0.03393 0.03379 0.03351 REFRACTIVE INDEX OF 1 - PHENYL BUTYL, PHENYL ETHER t 15 656 6439 R47RR 1 •J ti 1L•R4RR7 «-)kJ I 1.kJ R43P3 J iUfviU 1.53891 20 25 35 1.53818 5893 1.55189 1.54982 1.54747 1.54314 5790 5770 486 1.55087 5461 1 RR626 1 RR41R 4358 1.57534 1.57319 1.54414 1.54746 1.55574 1.56622 DENSITY at 25° C = 1.0086 1 Cadmium 6439 Sodium D MOLECULAR REFRACTION 656 • t 15 6439 0004335 D - C 20 25 35 0.C0496 Obs. 71.15 Calc. 70.86 CHANGE PER DEGREE 5790 5893 5770 .0004372 .0004483 D - 6439 0.00431 0.00425 0.00424 0.00423 DISPERSION 486 - D 0.01260 5461 0004403 Obs. 70.70 486 — 4358 0004RR7 4358 - D 0.02345 0.02337 4358 - 6439 0.02776 0.02762 0.02308 0.02731 ROGER CLARK DAWES R REFRACTIVE INDEX OF 2 * BROMO PHENOL 5790 t______656 -----15 20 -----25 -----55 ------ 6459 1.59171 1.58886 1.58671 1.58275 5893 1.59678 1.59391 1.59163 1.58770 5770 -----1.59514 1.59288 1.58895 5461 1.60207 1.59913 1.59688 1.59290 486 4558 ----- - - 1.62214 1.61976 1.61566 DENSITY at 25° C = 1.6609 Sodium D MOLECULAR REFRACTION 656 ------- 6439 .0004478 t 15 20 25 35 D - C ~ - Obs. 35. 43 CHANGE PER DEGREE 5790 5893 5770 .0004537 .0004126 D - 6439 0.00507 0.00505 0.00492 0.00495 Cadmium 6439 Obs. 34.98 Calc. 35.83 5461 .0004585 DISPERSION 486 - D 486 4358 .0004320 4358 - D 4358 - 6439 0.02823 0.02813 0.02796 0.03328 0.03305 0.03291 REFRACTIVE INDEX OF p - 3 CHLORO BENZYL PHENOL (C) t 15 6439 1.59949 1.59761 1.59566 1.59130 656 20 25 35 5893 1.60461 1.60268 1.60071 1.59636 5790 5770 1.60585 1.60398 1.60200 1.59758 5461 1.60993 1.60803 1.60601 1.60157 486 4358 -- 1.62926 1.62456 DENSITY at 25° C = 1.2031 Sodium D MOLECULAR REFRACTION Obs. 62.20 Cadmium 6439 Obs. 61.78 Calc. 61.84 \ 6439 .0004097 656 • — • t •— — ■ — D - C 5461 .0004181 486 . ---------- 4358 .000465 7 DISPERSION D - 6439______ 486 - D_______ 4558 - D_______ 4358 - 64 3D n nnc;i o n r\r\^ r\rf ^ w W 1 _L«J on 25 35 CHANGE PER DEGREE 5790 5893 5770 .0004123 .0004137 ------ 0 .0 0 5 0 5 0 .0 0 5 0 6 --------------------- 0 .0 2 8 5 5 0 .0 2 8 2 0 0 .0 3 3 6 0 0 .03 32 6 10 THE REFRACTIVE INDEX REFRACTIVE INDEX OF p - 3 CHLORO BENZYL PHENOL (A) t 15 656 6439 1.60106 1.59953 1.59792 1.59529 --------- 20 25 35 5790 5770 1.60743 1.60590 1.60434 1,60167 5893 1.60617 1.60468 1.60310 1.60040 5461 1.61153 1.61005 1.60841 1.60570 486 4358 -----1.62912 DENSITY at 25° C = 1.2106 Cadmium 6439 Obs. 61.59 Sodium D MOLECULAR ! REFRACTION 656 . ------ t 15 6439 .0002884 D - C Obs. CHANGE PER DEGREE 5790 5893 5770 .0002886 .0002879 25 35 5461 .0002914 DISPERSION 486 - D D - 6439 0 00511 0 00515 0.00518 0.00511 20 Calc. 61.84 62.02 486 4358 4358 - D 4358 - 6439 ------0.02872 ---------0.03383 REFRACTIVE INDEX OF o - 3 CHLORO BENZYL PHENOL t 15 6439 1.60030 1.59837 1.59629 1.59177 656 20 25 35 5790 5770 1.60671 1.60477 1.60262 1.59804 5893 1.60545 1.60348 1.60139 1.59681 5461 1.61077 1.60882 1.60668 1.60207 486 4358 --- 1.63002 1.62515 DENSITY at 25° C = 1.2088 Sodium D REFRACTION MOLECULAR ! 656 t 15 20 25 35 6439 .0004266 D - C Obs. 61. 97 CHANGE PER DEGREE 5790 5893 5770 .0004322 .0004335 D - 6439 0 .00515 0 .00511 0 .00510 0 .00504 DISPERSION 486 - D Calc. 61.84 5461 .0004353 4358 - D ------0.02863 0.02834 Cadmium 6439 Obs. 61.54 486 .------ 4358 .0004870 4358 - 6439 ------------------0.03373 0.03338 11 ROGER CLARK DAWES REFRACTIVE INDEX OF DIBENZYL PHENOL t 15 20 25 55 656_______ --------------------- 5790 6439_______ 5893_______5770 5461_______486_________4358 -----1.61880 --- 1.62447 -----1.64924 -----1.61670 -----1,62828 — 1.64687 -----1.61478 -----1.62057--- -----1.64475 1760531 1.61039 1.61191 1.61611---------1.64034 DENSITY at 25° C = 1.1095 Sodium D MOLECULAR REFRACTION 656 * t 15 20 25 35 6439 • D - C Obs. 86.21 CHANGE PER DEGREE 5790 5893 5770 nODAPflR • D - 6439 0.00508 DISPERSION 486 - D Cadmium 6439 Obs. Calc. 85.82 5461 nnriAl fln 4358 - D 0.03044 0.03017 0.02997 0.02995 486 4358 nnn444fl 4358 - 6439 0.03503 o - CRESOL F ig_ g, 6 - BROMO, 66 06 93 93 66 33 03 9 / 9 / & Do jw jm s u w ju o - CRESOL *6 BROMO, 9 6 £063 £533 £ 03 3 6 5 /3 £ 0 /3 £50? 6:003 £ 9 6 / £06/ £ 5 6 / £ 0 6 / 6 5 // S O // £ 5 9 / £ 0 9 / £S 5f ___________ /-/ 63 J?/ // 6 - BENZYL PHENOL a, s m iv a fJ M W J i 9. 2 - BROMO, i£ £ Fig. S f £0£3 ££33 £033 £ £ /3 £ 0 /3 ££03 £003 /- O / * ££6/ £06/ ££&/ £00/ & J m m / J A t/M £ £ /./ £Ot£/ £ £ 0 / £09/ £££/ £0£/ PHENOL 4 - BENZYL 3 - BROMO, 12. Fig- os &/ &/ Fig. 11. 3 - BROMO, 4 - BENZYL PHENOL zs £ -0 £ S ££S S 20Z S £ £ /S £ 0 /2 ££OZ ZOOS /. o / x £SG / £0& 2 /jm w ££& / £ 0 9 / jn m £ £ // £ 0 2/ £ 2 0 / 2 0 0 / £S £f £0£( PHENOL 6 - BENZYL 2 - BROMO. OF ETHER 14. METHYL :-J 9 + ' ___ Fig. ==p££!--- &£■ a£- e& a? +& e& 0& jm 0/ 0/ o -< 13. METHYL ETHER OF 2 - BROMO, 6 - BENZYL PHENOL x +t iv & z /s v ji £?/ Fig. +£ £0£Z £-J?3?S t9tt &>*? £9tZ £S0Z £00? £56/ £06/ SSG/ ,„o /* d /j& rn v ja m £00/ £££/ £d£/ ££S>/ £00/ £££/ £OSf ________ PHENOL 6 - BENZYL 2 - BROMO, OF ETHER 16. ETHYL Fig. OF «b> ft? £& e/ &/ +/ 15. ETHYL ETHER OF 2 - BROMO, 6 - BENZYL PHENOL ST Fig. AT SOGFFS&F £OZZ FS/& SO& SSOP £002 £S6/ £06/ £FO/ £00/ £££/ £CU/ £££>/ £0S>/ SSS/ SOS’/ _____ i-O/ y 2/3&W/7A/ JAMA________________________ ETHER BENZYL 18. PHENYL - Fig. &F 0F A? Fff 0F &/ &/ +/ o/ Fig. 17. PHENYL BENZYL ETHER F£ £0£F ££Z£ £OFF £ £ /F £OZF ££OF £OC£ £££/ £06/ £ £ 0 / £00/ £££/ £0£/ £ £ 0 / £ 09 / £££/ £OS/ ^ _________ /- £ff SSffff £Offff £9/3 £0/3 £903 £003 £90/ £09/ £99/ £08/ /_O /y & JffW f)N JAVM ££6/ £03/ £99/ £09/ £99! £09/ ____ PHENOL 30. DIBENZYL Fig. 33 os 9/ £>/ £/ 3/ Fig. 29. DIBENZYL PHENOL p0 jm i w & s m £0£3 ££33 £033 £S/3 £0/3 ££03 £003 ££6/ £06/ /- O /v ££»/ £03/ ££/./ SO// £££/ &J&W /7A / SMM £09/ £££/ £OS/ to d4 m c 02- d4 d4 m to t- co go Od m 0) 0 .0 Od4 in tO E- GO 02 O 02 2H02C rtoHWC 0 02 to t - tD 02 O OOOHH02Nin co co d4 d4 in in 0202C OC Od* O0202O OHH to to 22- t- CO C in in to to 02 to to to to to CD to co r- t- i> « 0 d4 d24 C OC OC OC D01020 02 2030302C 3OOco O C O d4 d4 02 o o o o o oo Ho o o o oo o o o o o o o o o o oO d 4 in to to t en E'­ 02 02 H H H H 02 W co d1 0 2020202C Oto c do4 rl rl rl rl rt r( Hrl rl 020202 r| O O O O OO O O O O O 02 to C- E“ 00 CO 00 00 m cn to d4 O O O H oo oo o o H m m to to to to E- C- E- t- t- E- t- CO 00 00 CO 00 02 d4 d4 a d4 02 P- £“ t- CO 00 CO 02 02 dl d4 H I- I C12 02 d4 m m to co to C- t- GO CO 02 03 d4 d4 in Oi 02 CV! Q to r- o o o o o o o o o o o o rl rl H O C O(3) 0) OIO 0 C OOOco d24 d4 rl rl rl 020202 i —1 —Ii —Ii —II —{' —I rH rl H H H020202C OC C dO i dO i O O rl H co co to co co co 003010)0)0)0)0)0000 OOHHHHH 020202o:02C OC OC OC OC Od4d4 d4 d4 in in in in in to to to to H H H O 2 C O t O t O ' « t f l O l O l r t t O < O t o r - C O C O C O O i 0 i O O O r l n l C \ 2 C v i f c a t O ^ ^ ^ m i r t C O ( 0 t Q t ‘- t ' - . E ‘~ C O C O O > C n O O O r l H inLOininLOinLOininiOinLOininiOlOininLOlOCOCOCDCOCOCOCOCOCOCOCOCOCOE'-r^C- - rl iC o 03c — 1C ic C*-H C ^DO C DcoO OH 0202 0202rl zO o C O C OG O02 C DOtOCOOrltQ^lfllDlflin^ O^ C Oc C O02o in _ 02 zC >rl O mOOOiiiOiOC C O oOo 3 C0 2C OC O >C o o OC OC 0O 20 2Hrl O O mO0 ^) ^C 0O 0o ot- tW **- C DC O^ 'Si^) O OO )co co CG to ^ o o H o o o 02 to ^ o in o O H H M O I W O l co o o o o i—I 02 to H rl t - i—I m co to to W r • o m O tO tD O C Q C D O lW lO C O H ^ C 0 0 2 i —l O O C J i C O C O t ’ C O C O l O o o H o o o c\2 co ^ o m o o o o o i—I 02 co ^ o o in o H o o 02 to o o in tot- r- cocoG 3a o o HH02O2COCO^'tflOC0tOC-t‘-COCO 02 02 CO C OC OC OC Od4d4 in lo lo in <0 (32 O O O O 02 02 02 02 inininincd OC OtoC OcoC O02 ^ ^ ^ sH02^ ^ ^ mininin 0 2020202C OC OC 02 02 02 o o o o o o o o o o o o o o o o o o o o o o o o o o o o o oroHo o o o o rH o o o o o o o o o o o o o o o o o o o o o o o oo o o o o oo o o o o o O -P C T w d4 -p to d4 02 ^ rtf ^ inininmin 02 OCDC OC OC OC OC-C-t* tin 3C0C 03inininininl0O C OC O r| rt-Hr| rl2r00C o02C Ofr c-rl O o303OC 0203< Oco03C 3mrl rlO 20 O 0 Oo 0 3in - -c Oto0 to0 mr| coinr| OC 20 2Hrl Oo z>£ *-C OC 0mmin C OC O0 oo0 30303C O03C O O O oo C O C O C O C OC O rHrl rl rl rl 5 rir-t:i2c\2cocod4d,d4incD(DcDC-cDcoco03oooHHC'2cQcQcQd4d,ininintot''t-cococDO3CJ2OHri <3 4 H o o o o o o in LO 03 02 in 03 rl 02 CO CO 02 m o CO rH CO r| 02 I> 02 t03 03 CO GO £- t- CO CO in in o4o Oo Oo o oOo oOo oc oi2o o4o o o2C Oo 02o C Od mo ri cod m 02C mOo O m rl 02C O mo o o in rlo o O o rl o 02C too ooo in rl 0 O oo o02 oC o orl O rl H H rl rl t - CD CO CO 03 H co ^ co r - 03 o 03 H 02 CO LO CO 2> CO d< rH in co r - co CD 03 O H W W C O r H in c O t- t- C O C J O H W M t- co co co co co co rH d* rH rH d1 to to ^ ^ in co o - I D C I l O H M ' f f f l C D M D m O H rH m co e- co CO CD 00 GO CO CD CO CO CD CO CD CO CO CO CO CO CO ! > CO CO 02 co ^ CD 00 co d< d< d 1 in in in co co co o - t - C\i 02 CO 03 03 03 03 O m tO ^ 02 CO CO rH d< in co to t - £~ co 02 02 CO CO CO CO d 1 rH rH d 1 rH d 1 m in in co co c - 7>- H £■— CO 00 CO H r - co 03 o 02 co ■>d) in co co O H h E~ CO 03 r H 02 co co ■d' in m H 02 02 02 co co co rH d< rH co rH 'CD t - co o H 02 02 CO rH d 1 in co c - r~ co 03 H H co co co co d 1 rH in co co to co t - O o O H H H 020202020202 02 02 02 02 02 CO CO CO CO CO CO CO CO CO d< rH rH rH 020202020202020202020202 02 02 0 2 C L 2 0 2 C O C O C Q C O C O C Q C O CO CO CO CO CO CO co CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO rH C- CO CO CO CO CO 03 03 03 O co 23- t - r - e- co 03 O O O O rf r ( D00 CO 02 CO rH rH O 02 CO CO CO rH O O O r l rl H 02 02 02 02 CO CO CO CO CO rH rH rH rH d * d 1 in d 1 d 1 rH in in in d< rH in in in co E~ CO CO CO 03 03 in co H r - (33 H co ao E -00 1- t o (33 CO C12 rH H M ^ (900 to If) t - CO H 02to^ inoo> 10 co r - co 'i1uo10 10 rH octftomi-ooow^ooc-oi O M r t * C O C - 0 > r l t O l O C ^ C O O cato 10 jot- CO00CO0)0)0 oo I) Sc II tototototo totototototototototo ooooo oooooo co if)in to I S I S CO CO coco -a*LO rl M K W If) (O is co o> toto ^1Tjl^1 tO ® S S 0 0 tO (D O )O )O ) ^ ^ TjlJ^l^ ^1^ I f ) If) if) CO CD H O)O)0)0)o o is is co co co co CI2 02 CO CO CO is co co co o) o) O O O r l r l W N K t O t O ^ H l 02 02 02 CO CO ^ if)If)COCOCDISISIsCOCOO) O)cj)coo)cococococococot-co oo ooo CO. to CO CD I S 0 0 O rH C 0 lf)C -< D O 0 2 C 0 lf)IS CO o 02 ^ CO If) o co o 02 O H 02 CO If) CO CD t - C v 2 c O '# if)C D IS lS C O C )O rH 0 2 C O 'tflf)C O IS CO 02 CO ^ ^1 l O CD O O rH rH I—I H 02 02 02 02 02 02 02 02 02 02 CD rH II ap CO CO CO I S I S I S 02 02 CO CO CO CO CO 00 CO 00 CO CO CD 0 ) O) H I S I S CO CO CO 0 ) ISC O C O IS C O C O C O C O C O C O 0) 0) 0) 0) 0) 0) 0 0 ) 0) 0) CD t - I S CO CO 0 ) 02 O rH H H 02 02 02 CO CO O LO E- 00 O 02 to o t- to oi h ^ CO O CO o w to in cd 0s- oi o w co in m (D t“ (D Oi O H 02 02 CO dl W CO M D E00 oo dl e- e» 000003000101O) O) o t —1 r —I i —I i —I i —I i—! oi O 02 CO d< CD E- 00 OI rl 02 *01 CD O) O O rl 02 CO dl in W CO E- 00 CD O O rl 02 to d< lo in cd E- 00 CO 01 O rl H 02 co -41 di m 01 dl CO CO E- E cd > di o o o H H H rl W CL! I —I I — I H r'l I — I H H r-l H H rl CV2 02 CO CO CO CO CO d1 d< 'CH d< in m m m co cd cd CD E- E- E- E- co 02020202CL202CO CO dl dl dl di W Cil M BI W M <0 CO CD CO E- E- t- E- E- E- E- E“ E- E- E- E“ E- E- e - e - c- c- e - e - E~ E- E- E- E- E- r- co co oo oo co oo oo co oo oo oo CO CD OI 01 01 £31 o rl in H 02 to CO to CO lo cd co > > 00 CO 00 CO 00 00 oo co co co co oo —I i—I CL2 02 02 02 to CO CO d< d* dt di in in in O O O rl rl 02 02 02 CO CO CO dl d< d< ID in Ltl CO CD E- E- E- 00 00 C0 CO OI 01 OI o O rl i o 01 CO 3C002c002rlrlOOOai01010000E-0-ZC-CDinc0unin'^-ctit0c00202HrlHO03 03O100c0E~0-E-CDCDinin^C0 CO CDC OCO COO OCD CDO O C O E - E - E - E - E - E - E - E - E - E - E - E - E - E - E - E - E - E - E - E - E - E - E - C D C D C O C p C O C D C D C D C O C O C O C O C O C O dl ECO rlCD CD dl CO 02 CDO 02 dl CD CO 0202 H C oo 0202 02 CO dl in e- ai 02 m co 02 t-rl CD H E- co O 02 -d1 CD 33 O 02 d1 0- 01 rl d1 COCD rl d1CO CD coe - co in di d l C O M H O O cd cor- e - co m di o e- in co 02 H O O H 02 CO m c-o co cd o di CD di O E- di 02dl E- O CO CD CD02 in CO H dl E- H dl E" rl d< t- H in co 02 o i cd co c - r - cd inin d< co co 02 rl rl O CD CD diCO 02 02 H o 02 rl CO CO o o o o o o o o i—I 02 co d* in CO dl CD C0 CD rl co in E- co o 02 dl CD E- CD O 02 dl in E- CD O 02 di in EO rl CD cd o 02 in m CD cd oo o H 02 co di m CD E- 00 CD O rl 02 CO dl in CD E- 00 01 O H 02 CO di in co E- co oi O O rl 02 CO dl in co d< di di in CD co dl dl dl dl d< rl 02 CO dl dl in c di dl O O O rl rl rl 02 02 02 CO CO dl di di m in CD CD dl dl cd cd co r- e- e- r- e- ^ ^ CD CD O rl H 02 02 CO CO CO CO CO di di di in in CD co oi dl dl H 02 02 CO CO CO di di in in in to e- t- c- co ao 00 CD CD 01 o o rl H rl 02 02 02 co co co co di di di in in in CD 01 o dl di in CO 00 CO CO 00 00 00 00 00 CO CO 00 CO dl dl d< dl dl di di d< di di di T^l *}l ^ o rl cd cd in 2> 00 O 02 to 02 cd cd 00000000010101 01 CD 01 01 01 01 01 01 01 CD 01 dididididididi didididididi in in m m in in in m in m in CD CD E- 00 CD O rl rl rl rl rl rl 02 02 co co di in in in in in CD E- E- E- 00 00 CO CD CD o o o rl rl H 02 02 02 cd CD in CD CD.CD E- E*- 00 00 CD 01 01 CD ^0cDininioinLndiindididicodico:i2coo2 0202riririririoocDocia20icooocoE-E-o-cDcDcoininininincQdiio < 0) O in H m to CD t- CO to cn O H 02 CO CO dl in coe- co ai ~ 02 co di in cd co 01 O 02 CO dl CO 0) o o «—i rH 03 CO CO to C\2 o O 0100 E- CD in dl CO 02 rl O Ol cd coe - co in d CO COCM rl O “ in CO 03 i—1 o 0> CO r- CD in o o o o o o rl 02 co di in o rl oo oooo 02 co d< m e o o o a rl 02 CO dl ID to GO rH to o 03 in T> r- to m ROGER CLARK DAWES SI Nd = 1.62080 i 73° 74° nD 0 10 20 30 40 50 0 1.30862 800 739 678 618 558 1-30499 A 6.2 D *ft D ml b *■-L b .U 6.0 656 606 6 6 7 7 7 607 6439* 519 9 20 0 0 1 521 Correction for wave length 486 5461 5770* 579G* 1516 518 134 109 7 8 4 9 7 8 4 9 8 9 4 9 9 9 4 9 20 9 4 9 519 1520 134 109 4358 2745 6 7 9 50 1 2752 TEMPERATURE < CORRECTION TABLE FOR PRISM NO. I. A N C 0 .24 n = 1.60 1.50 1.40 1.30 F D 0.39 0.28 Units of the fifth decimal of n G’ 0.50 | AN = 0.25 0.26 0.28 0.30 0.29 0.30 0.33 0.35 0.40 0.42 0.45 0.49 0.52 0.55 0.59 0.64 TEMPERATURE CORRECTION TABLE FOR PRISM NO. II A N C 0.70 n 1.70 1.65 1.60 1.55 1.50 1.45 0.72 0.74 0.76 0.79 0.81 0.84 D F 0.77 1.05 Units of the fifth decimal of n I an = n 0.80 0.82 0.85 0.88 0.91 0.94 1.10 1.13 1.16 1.20 1.24 1.28 G1 1.31 1.38 1.42 1.46 1.51 1.56 1.62 These two temperature correction tables were furnished with the instrument, by the Zeiss company of Jena. CONCLUSIONS A study of the Temperature - Re­ fractive Index curves agrees with the con­ clusion of George N. Falk (J. Am. Chem. Soc., 31, 86 (1909)) that in general the relationship is a linear function. Those compounds whose graphs do not fall in the linear classification are probably impure or there are errors in the measurement of the refractive index. The only compound that varied from a straight line graph was o - Bromo Phenyl, Benzyl Ether. The only point that does not coincide with a straight line graph is the value for the refractive index at 35°, for the hydrogen red line (6563 X). The red hydrogen line was very faint due to a partial ab­ sorption by the o - Bromo Phenyl, Benzyl Ether. The curves for Wave-Number Refractive Index are not straight lines. A few of the points for the lower wavenumbers (higher wave lengths) seem to fall on a straight and then there is a gradual drifting to the higher refractive index as the wave-number is increased. Evidently as the vibrations of light be­ come shorter and shorter the influence of the atoms in the molecule begins to have more and more influence on retarding these waves. This would be expected from observations made in X-ray diffraction. Broken lines are used to indicate the theoretical graphs at points for which no experimental values were obtained. The temperature chosen for calcu­ lating the molecular refractions was 25° C. The reason this temperature was chosen was chiefly that the measurements at this temperature were the most accu­ rate. That is, the constant temperature bath was more nearly the temperature of the surrounding air and therefore held more nearly to the temperature of measure­ ment. Also there were more compounds giving a reading for the various wave lengths at this temperature. The ob­ served molecular refraction for both the sodium D line and the cadmium 6439 & red line were recorded and that of the sodium D line was also calculated using the values for the elements given by Bruhl (Zeit. phys. Chem., _7, 191 (1891)) and Conrady (Zeit. phys. Chem., 3, 226 (1889)) for the n2 formula, about which more will be said later. The first formula employed was that developed by Lorentz (Wied. Ann., 9., 641 (1880)) and Lorenz (Wied. Ann., 11, 70 (1880)). They arrived at this same formula at about the same time, as may be noted from the references, and they worked inde­ pendently. Lorentz derived the expression from Maxwell1s electromagnetic theory of light while Lorenz got his expression from the undulatory theory, with the assumption that the volume of a substance is not com­ pletely filled with matter, but that be­ tween the spherical molecules there are spaces where the light can travel as rapid­ ly as it would in a vacuum. The formula is for the specific refractive power and is; g2 1 x - = R l1’ = Constant n2 - 2 d However as the molecular refractive power was desired in this investigation, a correction was made to this formula, giv­ ing: wherein n = refractive index for the liquid, d = density at the same temperature, m = molecular weight and M = molecular refraction. In most instances the calculated and the observed refractions were in close agreement. When the values of the calcu­ lated and observed refractions were not in agreement it was found the compounds were not sufficiently pure or decomposed while in the cup of the refractometer. The later conclusion of decomposition is definitely in error for the refractive index was con­ stant from the beginning to the conclusion of an investigation and during the several trials, unless the compounds were left in the cup for a period longer than four hours. It has been stated that the greater the molecular refraction of a compound the 32 ROGER CLARK DAWES greater its dispersion. This conclusion is proven an incorrect interpretation, when a study is made of these values. For instance, using three examples to point out this difference: 2 - Bromo, 6 - Methyl Phenol has a molecular refraction for the cadmium 6439 £ line of 42.59 and the dis­ persion measured between 4358 - 6439 £ is 0.03036 at 25° C. Methyl Ether of 2 Bromo, 6 - Benzyl Phenol has a molecular for the same wave length of 70.42 and a dispersion for the same interval of 0.03274 at 25° C. This would appear to be in agreement with the original theory. Choose any other compound and observe its relationship to the two just given; for example, the compound Ethyl Ether of 2 - Bromo, 6 - Benzyl Phenol. At 25° C it has a valug for the molecular refrac­ tion for 6439 A of 79.57 and the disper­ sion for 4358 - 6439 £ at 25° C is 0.03143. In this case the molecular re­ fraction is higher than either of the previously mentioned compounds but the dispersion lies between the values for the two. Such a phenomena is observed from a study of all the data and there­ fore a definite relationship between the dispersion and the molecular refraction of a compound does not appear to exist. That is, as accounted for in the Lorentz Lorenz formula, the density and not the dispersion is the influencing property So upon the molecular refraction. Not only are the differences in the observed and calculated molecular refrac­ tions due to the impurities in the com­ pounds, but they are also due to the fact that there is probably some unsaturation existing in these compounds which was not accounted for in the calculated values. The values used for the atomic refractions of the elements will vary from a constant val­ ue, due to the influence of unsaturation and structure in the molecule, Eykman (Chem. Weekblad., 3, 706 (1906)) has very thoroughly investigated the ethenoid link­ age and finds that it does not have a con­ stant value but is dependent upon the number of chains connected to the ethylenic car­ bons. In the calculation of the molecular refractions of these compounds it was as­ sumed that there were three double bonds or ethenoid linkages in the benzene nucleus. In all of these compounds an in­ crease in the temperature gave a decrease in the refractive index, but if the molec­ ular refractions were to be calculated it would be observed that there was a very slight increase in the molecular refrac­ tion for an increase in the temperature. Early workers, not having apparatus of the present precision type stated that the mo­ lecular refraction was constant within wide ranges of temperature. II A UNIVERSAL LABORATORY AMALGAM LAMP spectrum, was of the following composition; It has been found that certain mercury 60$; lead 20$; bismuth 20$; zinc 1/2$ and amalgams give spectra with intense lines cadmium 1/2 $. Geer(Phys. Rev., 16,94 (1903)) of the metal dissolved in the mercury. In this investigation a study was made of new very nearly duplicated this lamp of Arons. The first Cooper-Hewitt type lamp amalgams in order to increase the range of was constructed in 1901 and it was the first usefulness of amalgam arc lamps. The lamp that was given much attention by the range covered should include the visible public. This lamp was the result of lone spectrum and the degree of dispersion research on the characteristics of mercury should be sufficient to obtain approx­ vapor. The lamps were made of glass until imately monochromatic radiation. If only transparent quartz came into general use. the visible region of the spectrum is de­ Bussman (Engineer, _1, 81 (1908)) sired a lamp constructed from Pyrex glass states that amalgam lamps will not work. is applicable. Therefore the work of this According to his investigations the metals investigation was limited to lamps de­ are deposited at the electrodes, very short­ signed from Pyrex glass. Most of the ly after the lamps are started. lamps discussed in the literature are too Lowry (Phil. Mag., 18, 320 (1909J) complicated to give satisfactory operation and are designed from too costly materials. was the first to suggest the use of cadmium amalgam to obtain the cadmium red line for The first mercury arc was de­ signed by Way (Chem. News, 2 , 167 (i860)). spectroscopic and refractometric investiga­ tions. His lamp operated interruptedly and gave Knipp (Phys. Rev., 30, 641 (1910)) off a very intense radiation. The lamp constructed an enclosed arc lamp which was consisted of a reservoir connected to one portable. It could be evacuated and also side of a Bunsen battery and from this reservoir a fine stream of mercury trickled certain metals could be added without in­ terrupting its operation for long periods. into the lower vessel., which in turn was It was operated at low voltages with a re­ connected to the other side of the Bunsen sulting low intensity of radiation. battery. The result was a very intense Tian (Compt. rend., 156. 1063) source of light giving off a radiation described a lamp made from transparent which caused one's skin to have a ghastly hue. This effect led Gladstone (Phil. Mag., fused quartz. An insulated iron wire passed down the center of this quartz tube and made (4) 20, 249 (i860)) to carry on some contact with a drop of mercury at the bot­ investigations using this light. He made tom, which formed the cathode of the lamp. observations upon the spectrum and found The anode consisted of a small iron cylin­ it to be rich in yellow, green and violet but rather weak in the red radiations. The der. Ordinarily, direct current was used, light, although it appeared white, was not but alternating current could be applied. In order to use alternating current, a like sunlight because of the absence of double anode having two plates separated by these red radiations. mica, was employed. The advantage of this The first enclosed arc was con­ type of lamp was that it could be used on structed by Arons (Wied. Ann., 47, 767 low voltage. Also it could be conveniently (1892)). This lamp operated successfully and had a high intensity. Later Arons at­ lowered into liquids for photochemical ob­ servations. It possessed a great intensity tempted to obtain a more nearly white and a long life. radiation by the addition of other metals Darmois and Leblanc (Compt. rend., to the lamp. An amalgam which he found to 158, 258 and 401 (1914)) constructed a give nearly a continuous ultra-violet 34 35 ROGER CLARK DAWES lamp for use on a fifty-cycle, six hundred volt alternating current circuit, operat­ ing at 2,1 amperes with a power factor of 0.84, This lamp would not operate satis­ factorily even at six hundred volts. The effective life of a quartz mercury vapor lamp was increased through reinforcing the quartz tube by means of a highly refractive material, as "titanium zircon quartz" (vonRecklinhausen, U. S. Patent, 1, 188,587, June 27, 1916). This method proved to be quite satisfactory in prolonging the life of the lamps. Daguerre, Medard and Fontaine (Compt. rend., 157. 921 (1914)) designed a lamp giving nearly cold mercury light. It was essentially an inverted D-tube of fused silica with electrodes of invar. This lamp was enclosed in a silica flask and immersed in water, using suitable reflectors to focus the light on the apparatus employed. The arc was a very short one at che bend of the U-tube. This lamp consumed 18 am­ peres, either alternating or direct current, at seventy volts and yielded three thousand candle power. According to Bates (Phil. Mag., 39, 353 (1920)) the inefficiency of cadmium amalgam lamps was because most of the cur­ rent was carried by the mercury. For this reason the cadmium lines were of too low an intensity to be of practical use. Buttolph (Gen. Elec. Rev., 25. 741, 858 (1920)) pointed out that during the years 1902 - 1907, the condensing chamber of mercury arc lamps was standardized. Be­ tween 1907 and 1910 a commercial form of an alternating current mercury arc was devel­ oped. Continued research produced a lamp which would operate on a high power factor. In manufacturing, the lamps were filled with twice the amount of mercury that would be needed and heated to the melting point of the glass or quartz. Also the gases were removed from the electrodes by oper­ ating them on four thousand to six thousand volts alternating current. The rapidly boiling mercury displaced all foreign gases, and when the amount of mercury reached that for use the tube was sealed off. The Hanovia Quartz Mercury Lamp (Hanovia Chemical Company) was a type of the mercury anode lamp with ground-in con­ nections of glass or quartz. It was of a longer life but more complicated than the lamp not having the mercury anode and hav­ ing sealed-in electrodes. The latter lamp is represented by the Cooper-Hewitt Lamp. The spectra of these two lamps was essen­ tially the same and also the intensities were very nearly the same. Buttolph (Gen. Elec. Rev., 2 3 , 909 (1920)) found that the spectrum of theQ quartz mercury arc extended from 1850 A to 14,000 A* Coblentz, Long and Kahler (Bur. of Standards, Sci. Paper 330, 1918) found the total radiation to decrease from one-third to one-half in one thousand to fifteen hundred hours of use. As a result of the work done on a constricted mercury arc in a quartz capil­ lary by Harrison and Forbes (J. Am. Chem. Soc., 47, 2449 (1925)), Daniels and Heidt (J. Am. Chem. Soc., 52, 2151 (1930)) started their investigations upon their small quartz capillary arc lamp. A dis­ cussion of this lamp will be presented in the experimental procedure. EXPERIMENTAL PROCEDURE About the time this investigation was started an article by Daniels and Heidt (J. Am. Chem. Soc., 54, 2381 (1932)) appeared. A small but efficient mercury arc of a capillary design was described in this article. This lamp was made from a quartz capillary and it had an average life of about 24 hours. Some of the lamps had a life of only 10 hours. In this Investi­ gation a capillary of Pyrex glass was sub­ stituted for the quartz capillary. The re­ sulting lamp, having its electrodes sealed in with a soft, low melting point cement, was not satisfactory. Cold water running over the glass caused it to fracture im­ mediately. Without the cold water the pressure developed in the lamp was so great that it forced the electrodes from the end of the capillary. Finally these electrodes of tungsten were sealed into the capillary using potassium nitrite as a flux. These electrodes held, but the life of the lamps was only from 45 minutes to 60 minutes. The radiation from these lamps was very intense in the visible region but tapered off very rapidly in the violet re­ gion of the spectrum. Later in 1932 Daniels and Hoffman (j. Am. Chem. Soc., 54, 4226 (1932)) tried several amalgams In their lamps. These lamps deteriorated very rapidly and did not give lines of high intensity of the other 36 A UNIVERSAL LABORATORY AMALGAM LAMP metals, Besides the mercury, present in them. This led them to make the lamps us­ ing the metals hy themselves instead of using them in amalgams. The results were quite successful except that the lamps could Be used But once and then they had to be discarded. The Cenco mercury arc lamp worked very smoothly but great care had to Be exercised to prevent cracking the lamp upon starting it. It gave several hundred hours of very efficient operation, Before the glass weakened and fractured. The Cenco lamp was also furnished in a cadmium amalgam, but this lamp possessed a shorter life. After making a study of these lamps, the lamps in this investigation were de­ signed using the Cenco lamps as a guide and making a few minor improvements and alterations. A very thick ridge of glass was blown at the point where the two arms of the lamp were joined. The ridge served two functions, first it prevented a large quantity of the mercury or amalgam from distilling from the anode arm into the cathode arm of the lamp. Secondly, it re­ inforced the lamp where it seemed to have a tendency to Break down after long hours of use. The Cenco lamps were made from quartz or a special grade of Black Pyrex glass. All the lamps constructed in this investigation were standard Pyrex glass. After twenty unsuccessful at­ tempts a lamp of pure mercury was obtained which would maintain an arc for more than a few minutes. For a satisfactory lamp thorough evacuation is essential. It was found necessary to leave the lamp standing overnight, after the vacuum of 10 5 mm had Been obtained. If there appeared to be no leaks In the lamp it was heated to red heat, by means of an electric furnace. The tube was then evacuated, at this high temperature, for a period of not less than 24 hours. The vacuum was checked at fre­ quent intervals. Usually the vacuum varied between 10 mm and 10_s mm for the first 15 to 20 hours and then -remained at 10~5 mm. Keeping the tube at this pressure, pure mercury was allowed to enter slowly through a fine capillary. The amalgams were handled in the same manner as the pure mercury. The tube was then heated to the boiling point of mercury for a period of not less than 48 hours and at the low pres­ sure. This treatment was followed by run­ ning the lamp for an 8-hour period at the same voltage and current as for actual op­ eration but with the lamp opened to the vac­ uum system. This tended to remove the last trace of foreign gas from the lamp. Without this treatment the lamp failed very shortly after it was put into opera­ tion. While the lamp was still in opera­ tion, it was sealed off from the vacuum system. The vacuum system for this work con­ sisted of a Cenco HyVac pump, used as a fore-pump, and a mercury diffusion pump, which had been constructed in this labora­ tory by a former worker. The system was special in that there were no stopcockair connections. That is, the system was shut off from the air by mercury seals. A vacuum of 10~5 mm was very easily obtained with this system. The direct current lamps were con­ structed using 12 mm Pyrex tubing of the ordinary laboratory grade. Two lengths were taken, one 12 cm and the other 14 cm in length. One end of the 12 cm piece was sealed shut by means of an oxygen-gas flame. A hole was blown in the side of this piece, to fit the other 12 mm tubing, at a distance of 4 cm from the sealed end. The 14 cm piece of tubing was sealed on and a bend made at the junction of the two tubes to make the two arms parallel and about 1 cm apart. At the joint between these two pieces of tubing the glass was made thicker to take care of the extra strain due to the intensely hot arc at this point. Also the glass was blown in each a manner that a ridge was formed at this point to prevent the distillation of the mercury from the anode arm into the cathode arm of the lamp. Tungsten elec­ trodes about 0.75 mm in diameter, were sealed into the ends of the tubes by means of a potassium nitrite flux. First a bead of a special Pyrex glass, of the same ex­ pansion as the tungsten electrode, was sealed on the wire by means of this flux. The wire forming the electrode was made about 2.5 cm in length. This dimension was not of great importance, the main care being that the electrode extended into the lamp for at least 1 cm. Enough of the wire should be protruding from the lamp to make a good electrical contact. At 1 cm above the end of the electrode, the tube was constricted to keep the mercury in 37 ROGER CLARK DAWES contact with the electrode when the lamp was tilted for starting the arc. If this precaution is ignored the arc is apt to take place between the electrode and the mercury, and ruin the vacuum in the lamp by releasing gases absorbed on the elec­ trode. The short arm of the lamp was completely filled with mercury, while the longer arm was filled to within 5 cm of the junction of the two arms. The universal lamp was made in a manner similar to the direct current lamp just discussed. The two chief differences were that this "universal lamp had three arms in place of the two arms of the sim­ ple direct current lamp and also these arms were joined to a large condensing chamber, rather than together. A 125 cc Pyrex distilling flask was used as the foundation for this lamp. The body of this flask served as the condensing and arcing chamber of the finished lamp. The first step in the procedure of making one of these lamps was the sealing on to the bottom of the flask of a short length of 7 mm Pyrex tubing. This later served as the connection between the lamp and the vacuum system. In order to seal this tubing at the bottom of the flask it was essential that the whole flask be heated to a cherry-red heat, by means of a meaker burner. Then the oxygen-gas burner was used to heat the point where the tube was to be sealed on, and the sealing on operation was carried out in the usual manner. Then the Thole bulb was very carefully annealed, by the formation of a very heavy deposit of soot over the sur­ face of the bulb. The next step was to constrict the neck of the flask to a suitable diameter for sealing on a 12 mm by 8 cm tube of Pyrex glass. This opera­ tion completed, the flask was heated to a cherry red and two other pieces of Pyrex glass of the same dimensions were sealed on the bulb at opposite sides of and ad­ jacent to the neck of the flask. Again a very thorough annealing operation was carried out. A line drawing on the next column shows the lamp proper and the meth­ od of introducing resistances for its efficient operation is indicated. The 20-ohm resistance units were obtained by the use of ordinary cone-type heating units. The 10-ohm resistance was made from nichrome wire wound on insulating m a t e r i a l , such as Pyrex glass. The sodium, cadmium, zinc, gold and silver amalgams were made by adding the pure metals directly to the mercury, either at room temperature or at some elevated temperature. As the amalgams were readily oxidized by the air, it was necessary to carry out the reaction between the metals and the mercury under the surface of tolu­ ene. The other metals were made into amal­ gams by the electrolysis of a salt solution .rvvvvd/vvvy 80 - n - 110-VOLT ALTERNATING CURRENT ARC 28 A UNIVERSAL LABORATORY AMALGAM LAMP of the metal. The cathode of these elec­ trolysis cells consisted of pure mercury. The solutions were electrolyzed until the polarization at the electrodes caused the interruption of the flow of electric­ ity through the electrolyte. The am­ perage and voltage were carefully checked throughout the operation. With this data the amount of metal in the amalgam was very closely determined. EXPERIMENTAL RESULTS Lamp #80, made from pure mercury, lasted for a period of 80 hours before it fractured and lost its vacuum. This was the first lamp that operated successfully and its failure seemed to be gradual. At first the intensity of the radiation de­ creased rather rapidly, followed immed­ iately by a clinging to the tube of the mercury. Yellow and red colorations ap­ peared in the mercury, due to its oxida­ tion. The lines in the spectrum of this lamp were exactly the same as those found in the Cenco pure mercury lamp. Lamp #21 was made from this same sample of pure mercury using the additional precau­ tion of a longer period of evacuation. This lamp gave several hundred hours of intense and pure mercury light. Its ac­ tual life was not measured, for it was wrapped with asbestos and allowed to be­ come very highly overheated, to observe if there was any difference in the radia­ tion. The lamp only lasted for an hour under this abuse and during that space of time no new lines were observed in the spectrum of the lamp. The observation of this lamp led to the conclusion that it produced a greater intensity of radiation than any other lamp constructed. The first lamp consisting of an amalgam was made using a 0.1$ cadmium amalgam. The attempt to make this amal­ gam in the air was a failure as the amal­ gam oxidized on the surface. When the amalgam was made in a vacuum or under the surface of toluene the oxide film did not form. Lamps #22, 23 and 24 were made using a cadmium amalgam of the same con­ centration as given above. Because of in­ complete evacuation and leaks, lamps #22 and 23 were not satisfactory. Lamp #24 gave over 500 hours of service. When this lamp was first started the cadmium red line, 6439 1 , was very faintly visible. After 24 hours of use the red line was too faint to be seen, unless the Wratten Filter #24 was used to filter out all of those radiations below the mercury line at 5790 A. This lamp gave quite a different spectrum from that of the Cenco amalgam lamp. The intensities of the cadmium lines were very much greater for this lamp and also many lines were apparent in the spectrum that were not found in the spectrum of the Cen­ co lamp. Lamp #25 failed to hold a vacuum because of faulty seals in the electrodes. Lamp #26 was constructed and filled with a 1$ cadmium amalgam. The amalgam in this lamp oxidized either because the vacuum was poor in the lamp or because the con­ centration of cadmium in the amalgam was too high. This lamp radiated a spectrum of even higher intensity than lamp #24. The concentration of the cadmium should be increased to give the radiations from that metal a higher intensity. By the electrolysis of a 10$ solu­ tion of potassium sulfate, an amalgam con­ taining potassium was obtained. The con­ centration of the potassium in this amal­ gam was 0.2$. Lamps #27, 28, 29, and 30 were made using this amalgam. Of these four lamps #30 was the only satisfactory one. No potassium lines were visible in the spectrum of this lamp, either because the mercury carried the greater share of the current passed through the lamp, or because the temperature in the lamp was not sufficiently high to cause the excita­ tion of the potassium radiation. It should be noted that the anode of this electrolysis cell was of lead. The cur­ rent passed was 0.5 ampere. Ten other lamps were made containing 0.2$ and higher concentrations of potassium, but none of the lamps radiated the potassium lines. When the arc was first struck an intensely red radiation appeared and lasted for a period of ten seconds, after which the radiation was the same as for the pure mercury arc. In these lamps the glass was very rapidly attacked and the maximum life was 24 hours. A rapid reaction between an alkali metal and the glass would be expected at the high temperatures main­ tained in the arcs of these lamps. ROGER CLARK DAWES An amalgam of lithium was obtained by using the same electrolysis cell and employing a saturated solution of lithium chloride. A detailed study of this lamp could not be made, because the lithium attached the glass very rapidly. The con­ centration of the lithium in the amalgam was 0.1$. The first few seconds of opera­ tion of this lamp gave a radiation rich in the lithium red line, 6707.86 A. A relatively stable amalgam was formed by dissolving bismuth metal in hot mercury. This amalgam seemed to be free from oxidation upon the exposure to air even at elevated temperatures. Lamp #41 was designed using a 1$ amalgam of bismuth. The radiation from this lamp was of a high intensity, but the amalgam attacked the glass very rapidly. Two very faint lines at 4722 and 5552 A, were excited by the bismuth, during the extremely short twohour life of this lamp. Lamp #42 made from this same amalgam, also had a life of two hours. A low current gave lines of lower intensity in lamp #42, Through the electrolysis of a sat­ urated solution of barium chloride, a 0.3$ amalgam of barium was obtained. The lamp had a high intensity throughout its life of 50 hours. The following barium lines were identified in its spectrum: 4554, 4628, 4673, 4899.9, 4934 and 5535 A. These lines were of high intensity for the first ten hours of operation and then rap­ idly faded out until only the mercury lines were apparent in the spectrum. Ev­ idently the barium had combined with the glass of the lamp during this brief period. This lamp #43 fractured while it was in op­ eration and immediately ceased running. An amalgam of 1$ zinc was made un­ der the surface of toluene. This amalgam was placed in the evacuated lamp #44 through the fine capillary. Although this lamp operated efficiently, no zinc lines appeared in the spectrum. Through some mistake, the zinc was low in this amalgam and instead of being present in the amount of 1$ was only of a concentration of 0.5$ zinc. The following lamps were constructed: #45 and 46 containing 1$ of zinc, #47 filled with a 2$ amalgam of zinc and #48 with a 4$ zinc amalgam. With the excep­ tion of #48, all of these lamps tailed and were difficult to start. Lamp #48 operat­ ed excellently and the following zinc 39 lines appeared in its spectrum: 4680, 4722 and 4810 2. The second time that lamp #47 was started, the pressure built up inside and bursted the lamp, scattering a very fine spray of the amalgam through­ out the laboratory. Crystals formed in the amalgam of lamp #48 after 20 hours of use and in order to start its operation the lamp was heated with a bunsen burner until the amalgam liquefied. Another lamp #49 filled with a 3$ zinc amalgam did not give zinc lines of a sufficient intensity to be of any use. After these attempts with one metallic component amalgams, attempts were made to construct lamps consisting of two or more metallic components. Lamp #50 represented the first of these attempts and it operated efficiently. The following amalgam was employed in this lamp: mercury 96$, cadmium 2$ and zinc 2$. This amalgam had a tendency to solidify and the concen­ trations were changed to: mercury 97$, cadmium 2$ and zinc 1$ for lamp #51 and mercury 98$, cadmium 1$ and zinc 1$ for lamp #52. The intensities of the cadmium and zinc lines were very low in these lamps. The success of this addition of two metals to the mercury led to the con­ struction of lamp #53 using: mercury 97$, cadmium 1$, zinc 1$ and barium 1$. Due to incomplete evacuation this lamp did not operate. It was noticed at this time, and later in the investigation, that the more metals present in the amalgam, the more difficult the satisfactory evacuation of the lamp. Lamp #54, filled with this same amalgam, worked satisfactorily for a short period of time. The glass was attacked very rapidly and the intensity dropped. Because of the interaction between the amal­ gam and the glass the lamp was ruptured in several places. Several other lamps were made from this same amalgam and an amalgam which contained less barium. Lamp #56, of the same formula as clamp #54, had a life of only five hours. Lamp #57 was filled with an amal­ gam of mercury 95$, bismuth 3$, zinc 1$ and cadmium 1$. This lamp had a short life due to the rapid attack upon the glass by the amalgam, indicating that the percentage of bismuth was too high. Lamp #59 was filled with a silver amalgam containing 0.2$ of silver. There A UNIVERSAL LABORATORY AMALGAM LAMP 40 were no silver lines apparent in the visi­ ble region of the very intense radiation from this lamp. Upon tilting the lamp to start the arc the electrode seal was broken so this same amalgam was placed in lamp #60 which had. a life of 75 hours. Lamp #67 was designed to be filled with an amalgam consisting of silver 0.1$ and cadmium 2$. This lamp did not radiate any new lines and had a life of 48 hours. It was observed that the cadmium lines seemed to be inhibited by the addition of silver to the amalgam. Lamp #68 contained an amalgam of mercury 99.99$ and gold 0.01$, which gave a radiation due to gold at 4811 . Lamp #69 was filled with an amalgam richer in gold, having a formula: mercury 99.9$ and gold 0.1$. This lamp radiated gold lines at 4065, 4792 and 4811 . Lamp #70 was designed as a source of light for refractometric investigations. This lamp was filled with the following amalgam: cadmium 1$, mercury 98$ and sodi­ um 1$.' This lamp was unsatisfactory be­ cause the sodium and cadmium lines were of a very low intensity. All of the lamps discussed were studied in duplicate. The conclusions drawn from these duplicated lamps were the same as for the originals and therefore the results are not tabulated. Lamp #122 contained an amalgam exactly the same as found in lamp #70. It was interesting to note that upon starting lamp #122 the mer­ cury green line at 5461 2 had a yellow cast. This was caused, either by the mer­ cury exciting a yellow radiation in the sodium vapor present in excess in the lamp, or by an instantaneous radiation of the yellow sodium line effecting the observer's eye to produce this yellow appearance of the mercury line. The latter conclusion seems a better reason for the cause of this phenomenon. Three other lamps #123, 124 and 125 were designed in which the concen­ tration of the sodium was increased to 2, 3 and 4$ respectively. These lamps gave no sodium radiation and rapidly attacked the glass rupturing the lamps within five hours from the time they were started. 2 2 Lamps #126 and 127 were made of an amalgam containing silver 1$, cadmium 1$, zinc 1$ and sodium 2$. These lamps gave no desired lines of cadmium or sodium and were very short-lived, probably not over 2 hours. Because of the failure of electrode seals lamps #128 to 149 were unsatisfac­ tory. The warm, damp summer atmosphere was the cause of the fracture of the electrode seals. Shortly after they were made they would hold a vacuum, but upon standing over­ night the vacuum was lost and minute cracks were observed at the seals. Lamp #150 was filled with mercury 94.5$, cadmium 5$ and zinc 0.5$. Upon standing the amalgam in this lamp solidi­ fied. Lamp #150 produced an excellent radi­ ation of the cadmium red line, 6439 A. This lamp is still in use after over 500 hours and no decrease in the intensity of the radiation is noticeable; neither does there seem to be any attack upon the glass by the amalgam. The zinc seems to increase the in­ tensity of the cadmium radiation at the red end of the spectrum and also seems to act as a protective agent for the glass. The construction of the universal lamps was discussed in the introduction. It is sufficient here to mention that five pure mercury and five cadmium amalgam lamps con­ taining 5$ of cadmium were designed. These lamps gave a radiation of less intensity than with the direct current lamps. The reason for this decrease in intensity being that the arc was not confined in as small a space as in the case of the direct current lamps. Also the life of these universal lamps was shorter, because the increased volume made it difficult to evacuate the air water film from the surface of the glass bulb. The lamp operated efficiently on 110volt alternating or direct current with an intensity of radiation of about half that obtained with the small direct current lamps In the case of the cadmium amalgam the red line was of an intensity only one-tenth that of the direct current lamps. This decreased intensity of radiation was attributed to the lower temperature of the arc in the univer­ sal lamp.