Vox,. 42. MARCH, 1920. No. 3.

TME JOURNAL

OF THE

American Chemical Society with which has been incorporated the

American Chemical Journal (Founded by Ira Rernsen)

TWENTY-SIXTH ANNUAL REPORT OF COMMITTEE ON ATOMIC WEXGHTS.

DETERMINATIONS PWLISHED DURING 1918 A N D 1919. BY GREGORY PAUL BAXTER.

Received Februnry 12, 1920.

For the first time since 191G the International Committee on Atomic In the case of elements af- Weights1 recommends changes in its table.

fected by the report the old and new values are given below:

Argon 39.88 39.9 Roron. . . . . . . . . . . . . . . . . . . . . X I .o IO .o Columbium. . . . . . . . . . . . . . . 93 .s 93.1 Gallium . . . . . . . . . . . . . . . . . . . 69.9 70.1 Nitrogen . . . . . . . . . . . . . . . . . . 14.01 14.008 Thorium.. 232.4 232 .IS 'Yttrium. 88.7 89.33

1916. 1920. . ....................

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Tile individual determinations published during the last two years are :is follows:

Belium.--Guye2 continues his discussion of general errors affecting atonl.ic weight determinations, with especial reference to exact weighing and the microbalance. Taylor's3 results on the density of helium are recalcu- lated, with the result 3.998 for the atoniic weight of this element.

1 'rHIS JOURNAL, 41, 2881 (1919). J . chim. phys., 16, 46 (rgr8).

8 Phys. Rev., IO, 653 (1917).

328 GREGORY PAUL BAXTER.

Q P Q ~ and Fluorine.-Smith and van Haagenl converted vreighed quantities of very carefully dehydrated borax into a number of different soclium salts, by evaporation in a platinum flask with methyl alcohol and acid. In some cases the acid used during the expulsion of the methyl borate corresponded to the sodium salt finally weighed. In others formic acid was errbployed in the preliminary evaporation and the formic acid was eventually displaced by the acid finally combined with thesodium. In 3 experiments the sodium fluoride which was first obtained was weighed and then was converted to sulfate quantitatively, and in one experiment a similar process was adopted with sodium chloride. Except in the case of sodiam fluoride and sulfate, one experiment only of each sort was completed. The same specimen of borax was used throughout. This was prepared by combining sodium carbonate with a slight excess of boric acid, and crystallizing the product many times with one intermediate fusion. Va~cuurn weights are given. C = 22.997; s == 32.069; = 35.457.

EXPt. Wt. of NazBO. Wt. of salt.

IV 0.89853 0.52112 XaC1

XaiSOd 0.63313

NaF

Na2S04

NazS04 VI 1.59374 I .r2315

Nan‘Oa VI1 I ,86458 1. . 5?25O

v 0.69595 0.29042

0 .4.9113

VI11

IX 1,99197 o ,83003 NaF

Na&O4 I .i2889

Nap

NanSQc I .86597

x I .60201 0,56757

IX 2.64768 I ,10329

At. wt. 3.

IO .896

I O .905

I O ,901

IO .898

IO. 900

10.903

ro.902

10.896 Average, IO .goo

At. we. P.

19.002

19.005

n9.006

19.004

19.006

19.008

19.005

19.002 19.005

The International Committee on Atomic Weights has adopted this new

Carbon.--Stahrfoss2 has determined the densities of acetylene, ethylene value for boron.

1 Carnegie Inst. Publication, 267, 1918. .7. Ch’k. phys., X6, 175 (1918).

REPORT OF COMMITTEE ON ATOMIC WEIGH~~S. 329

and ethane. Acetylene was prepared by dropping a mixture of calcium carbide, potassium dichromate and ferrous chloride into water, and, after scrubbing and drying, was fractionally distilled. The numbers repre- sent the weight of the liter in grams. In the last column the correction for deviation from Boyle's law is applied.

Globe A. Globe B Globe C Corrected 319 58 cc. 578 80 cc 893 10 cc. Average. average.

I , 17876 I 17905 1 .I7871 I . I 7884 I ~ 17926 I .I7849 I .I7897 I . r y g 2 1 I . 17889 I .I7925 I ,17842 I . i 781.1 1.17842 1.17879

Average, I .r7910

Ethylene was prepared from ethyl alcohol and phosphoric acid, and also, a.fte:r purification and drying, was purified by fractional. distillation.

Corrected Globe A . Globe 9. Globe C. Average. average.

I .26030 I '26031 1: -2.5997 I .2601g I ,26094 I ,26177 I ,26078 I .26183 I .26146 I ,262 IO h ,2603 I I .zGooz ( I ,26396) I .26016 I ,26096

Average, I .26133

Staktfoss prefers to reject the second series. I f this is done the average is I .zSogg.

One sample of ethane was made by allowivg ethyl bromide to act upon magnesium and decomposing the prodmt with water. Tne gas was puri- fied and fractionated.

Corrected (Globe A. Globe R. Globe C. Average. average.

I: ,35466 1.35430 I .35502 I .pi466 I .35632 I 3,5400 I .35482 I .35411 I ,3562 I

I .35416 1.3552r I .354.68 I .35668

Average, I .35629 1.35399 1.35381 1.35390 1.35585

A second sample of ethane, resulting from the action of ethyl cyanide tipmi sod.ium, was purified as above.

Corrected

1.35493 1.35459 I .35579 1.35492 P ,35684 .3.4450 I .35456 I .35525 1.35477 1.35701

1.35450 I .35440 1.35489 1~35460 I .35687

Mabe A. Globe B. Globe C. Average. average.

Average, I .35690 I .35660 Average of both series,

I f the results of the last 7 experiments are averaged with 12 previously obtahed by Baume and Perrot' and corrected, the final value I .3565 i s obtajned.

It. i s stated that by the method of critical constants the atomic weight of carbon is calculated to be I z . 00, but details of the treatment of results are kcking.

7. ckim. phys., 7, 369 (1909).

330

Batuecasl also has determined the density of ethylene, prepared by the reaction of alcohoI on ( I ) phosphoric acid, (2) boric acid, (3) sulfuric acid, and (4) by the catalytic decomposition of alcohol. After purifiea- tion and drying the ethylene was fractionally distilled. In the Pol~ow- ing table the correction for deviation from Woyle's law has been applied:

Methad of Globe KT. Globe 3 . Globe 4 preparatian. 615.23. 602 69 793 70 Average.

Y preliminary I

I 2

3 3 4 4

1.25985 L ,26033 I .26047 I .25999 x ,26002 I .25022

i ,26045 I ,26029 T ,26003 I ,26047 1 ,26050 1.26012 i ,26037 li I 26029 1.25046

I. .26009

I .26041 I .26029 r .26052 I: .26025

I .26045

Y .26052 I ,26050 I .26047 I ,26032 I: .a6031 ~ I .26035

I .26o31 I .26021

-___- --__ _I_____ -__I_

Average, I .26022 1.26029 I .26042 I , 2 6 0 3 ~

By comparison with oxygen the molecular weight of ethylene and the atomic weight of carbon (H -- x .0077) are computed.

By the molecular volume method By the limiting density met.hod By the critical constant method

63 = 11.996 e = 11.999 C = 12.005

Argsn.-I,edue2 finds the specific gravity of argon referred to air a t o o to be I .3787$ and the coeRieient of deviation from Boyle's law a t 14' to be IO a 2 X IO-^ per em. of mercury between one and five atmospheres. The molecular and atomic weight of argon by the method of limiting densities i s found to be 39.91. The International Committee has adopted the value 39.9.

Gallium.-Richards, Craig and Sameshimas purified gallium t r ~ c ~ ~ o ~ ~ d e by 3 distillations in chlorine at 220--230° , 3 in chlorine at 175', 3 in nitro- gen a t 90--110' and 5 a t 63-80' in vacuum. In one preliminary experi- ment 0.4394 7 g. of the chloride was weighed in an exhausted glass bulb, and, after solution, was compared with silver. The chloride required 0.80587 g. of silver and yielded I .o7oS7 g. of silver chloride, all in vacuum. These data give the values 70.09 and 7 0 . I I for the atomic weight of gallium. The value 70. I has been provisionally adopted by the Pnter- national Committee on Atomic Weights.

rsmine.--Guye4 discusses the calculation of the deviation of a gas from Avogadro's rule by the method of compressibilities, with special reference to hydrobromic acid, and from the data of MolesEi and Reimane

J . chim. phys., 16, 322 (1918). Comfit. rend., 167, 70 (1918); Ann. Phys., 9, 5 (1918).

8 THIS JOURNAL, 41, 131 (1919). 4 J . chim. phys., 17, 141 (1919). sIb+bid., 14, 389 (1916). BIbid., 15, 293 (1917).

RICPORT 03 COMMITTEE ON ATOMIC WEIGHTS. 33 I

finds the value of I + X a t one atmosphere to be T .oog34. On the basis of this value Guyel computes the atomic weight of bromine to be 79.920, using the average corrected weight of the normal liter as found by Moles and Reiman, 3.64423, and that of oxygen, I .@go4 ( I + X =: I .ooog), IF the individual values of Moles, 3.64441, and Reiman, 3,64404, are used, however, the values 79.924 and 79.915 are obtained for bromine.

ttrium.--lt(remers and Hopkins2 have determined the ratio of yttrium chloride to silver, using yttrium salt which had been purified for a previous ~ ~ ~ v e s t i ~ a t i o n ~ s Vacuum weights are given. Ag = 107.88; G1 = 55.46.

Sample. Wt. of YCls. Wt. of Ag. Ratio.

YCls : 3 Ag. At. wt. u.

04-6. ........ 3.31143 5.47636 o .60468 89.32 OQB . . . . . . . . . 2.31979 3 .83587 0.60476 89.34 Oa-a... . . . . . . 2.26815 3 .7.5045 0.6047'7 89 -35 0&.--.8... . . . . . . 2.29376 3.79302 0.60473 89.33 TIL, . . . . . . . . . 2.00731 3 .SI977 o ,60465 89.31 R4 . . . . . . . . . . . r.97610 3.26827 o .60463 89.30 R&. . . . . . . . 2. I7949 3 .Go389 0,60476 89.34

Average, 139.33

This value has been adopted by the International Committee on

in.---Brauner and Krepelka* have compared tin tetrabromide, dis- .Atomic Weights.

tilled in vacuum, with silver. Wt. of BnBrr. Wt. of Ag. Ratio, SnBn : 4 Ag. At. wl. Sn.

1.11964 r .10206 p .or595 118.73 1.97428 1.94359 1 .or579 118.67 2.35469 2 31788 1 .or588 118.71

Average, I 18.70

Preliminary Series.

Final Series. 5 .1n788 5.03796 I .or586 118,702

2.46875 2 .43<)35 I ,01580 118.674 0.99510 0.9796x 1 .or581 118.679 I .69834 I ,67172 1 .or592 118.727 3 442% 3.48737 r .or585 118.697 3 82180 3.76199 I .01590 118.717

Average, 118.699

This value is in close agreement with the recent results of Briscoe, and Baxter and Starkweather.

Dg.sprosium.-Kremers, Hopkins and angle6 purified dysprosium ma- terial by fractionation of the (I) bromate and (2) ethyl sulfate. Then

1 J . chim. plays., 17, 171 (1919). 2 Tars JOURNAL, 41,718 (1919). * Ibid., 38, 3332 (1916). 4 Rozpravy Ceskts Akademie v?d a umlne'. The data have been commuiiicated

privately to Dr. Krepelka. THE3 JOURNAL, 40, 598 (1918).

332 GREGORY PAUL EAXT'ER,

weighed quantities of oxide were converted to chloride in a weighed quartz flask. As the oxide was subsequently found to contain carbonate, the results of this series of experiments are rejected by the authors, and therefore are not given here. Next, the chloride, which h2.d been ren- dered anhydrous by fusion in a current of hydrogen chloride, was com- pared with silver in the usual way. MTcights are corrected to vacuum. Ag = 107.880.

Ratio At. wt.

Ethyl sulfate. . . , J ,04979 I ,26301 I .Z0309 162.62 J .95604 2 .35380 I ,20334 162, j 7 1.47475 1.77504 T ,20362 162 ..5r I .262 j3 I .SI991 I ,20386 162.45 0.99677 I ,20033 I ,20421 162.38 2 ,25129 2 ,70992 I .20371 162.49

Bromate. I . . . . . . 2 ~23374 2 ,68806 1.20338 162.56 x ,20763 1.45325 I ,20339 162.56

Average, 162.52

Sample. MrL. of DyCh Wt. of AS. 3 Ag : DiCia. D?i.

Erbium.-Wishers, I-Xopkins and Balkel made a comparative study of methods for the separation of yttrium from erbium, and completed pre- liminary experiments in which a weighed quantity of erbium oxide was converted to chloride, which was weighed. The subsequent discovery that erbium oxide made from oxalate contains carbonate even after igni- tion a t 900°, not only makes the results of these experiments of doubtful value: but also, as the authors point out, throws suspicion on all experi- ments where the weight of a rare ezrth oxide made by ignition of the oxalate has entered into the computation of the atoniic weight.

.-HonigschmidZ lound the atomic weight of thorium- in density determinations to be 207.77.

In another investigation upon thorium-lead, HGnigschrnid3 has deter- mined the atomic tveight of lead from 3 specimens of Ceylon thorianite, of the following composition :

I. 11. 111.

Thoria and rare earths 78.2 79.11 72.52 Uranium oxide. . , , . . . . T ' t .g 12.2 18.1

Pb . 2.34 3 , I I 3.5 At. wt. Pb.. , . . . , . . . . . , . . . . . . . . . . . 207 . 2 I 206 .91 206 ,84

Fayans, Richter, and Rau~henberger~ separated the lead from thorite containing 30.1% of thorium, only 0.44% of uranium, and o.35yo of lead. Three determinations of the atoniic weight of the lead by HSnig- schmid gas-e an average value of 207 .go.

THIS JOCRNAL, 40, 1615 (1918). Plzysik. Z., 18, r14 (1917). Ibid., 19, 436 (19x8); 2. Elektrochenz., 25, 91 (1919). Sitzb. Heidelberger A k n d . Wiss., rgr8, p. 28; J . Chenz. SOC., 116, IT, 7 .

DETERMINATION OF HALOGEN IN ORGANIC SUSS”~ANC~S. 333

Davis’ purified ordinary Bead and lead from samarskite by crystalliza- ti,, of the nitrate and chloride. Analysis of the chloride gave the value 2 0 7 . 2 7 far the atomic weight of common lead and 206.30 for that of rxlioactive lead.

The samarskite was found to contain 1 2 . 2 1% uranium and I . 03% thorium.

J. $. van I,aar2 appiies a method of critical constants to the determina- tion of the atomic weights of several elements, using the density data of various experimenters, with the following results: R = I .0077o; E e = 4 ooo;G = a z . o o ~ ; N = 14 004;s = p . 0 6 0 ; C l = 35.46o;Br = 79.922.

Moles3 discusses critically revisions of atoniic weights published in 11917.

Guye and Renard4 consider the distribution of errors in determina- tions of atomic weights.

Guichards briefly compares methods of atomic weight investigation. CAMBRID6S3, M A S S .

[h\ONTRIBUTION FROM THE CHGMTSTRY DEPARTMENT OF THG UNIVERSITY OF ILLINOIS. 1 APID ~ E ~ ~ O D FOR TME

HALOGEN IN ORGANIC SUB BY W. A. VAN WINKLE AND G. McP. SMITH.

Received November 22, 1 9 ~ 9 .

~ntroduction.-~he present investigation is a continuation of work taken up by G. McP. Smith a t the request of the Bureau of Mines shortly after our entry into the war, which led to a scheme for the rapid, approxi- mate determination of certain gases (e. g of chloropicrin) in the air by a method of simple combustion.

In view ob‘ the difficulties involved in many of the available methods for the determination of halogen in organic compounds, this method of simple conlbustion was considered worthy of further investigation. And it will be shown in the experimental part that the method in its simplest form is capable of wide application, and that it can be depended upon

rnish reliable values. evious ’Work.-This method or” analysis has frequently been pro-

posed, and nothing could be simpler in principle. Trouble has always been met with, however, in carrying out the combustion, and often in

J . Phys. Chem., 22, 631 (1918). J . chim. phys., 17, 266 (19x9); Chenz. Weekblad, 16, r2q3 (19x9). J . c h k . phys., 16,350 (1918). Avch. sci. phys. Tzat., 44, 402 (1918).

6 Bull, SOL chim., 21, 238 (1917) 6 Excerpt from a thesis submitted to the Graduate Faculty of the University of

Illinois by N’. A. Van Winkle, in partial fulfilment o€ the requirements for the degree of Doetor of Philosophy in Chemistry.