TWENTY-SIXTH ANNUAL REPORT OF COMMITTEE ON ATOMIC

Vox,. 42.

No. 3.

MARCH,1920.

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 1918A N D 1919. BY GREGORY PAUL BAXTER. Received Februnry 12, 1920.

For the first time since 191G the International Committee on Atomic Weights1 recommends changes in its table. In the case of elements affected by the report the old and new values are given below: 1916.

Argon ..................... 39.88 Roron. .................... X I .o Columbium. . . . . . . . . . . . . . . 93 .s Gallium . . . . . . . . . . . . . . . . . . . 69.9 Nitrogen . . . . . . . . . . . . . . . . . . 14.01 Thorium.. . . . . . . . . . . . . . . . . 2 3 2 . 4 'Yttrium. . . . . . . . . . . . . . . . . . . 88.7

1920.

39.9 IO .o

93.1 70.1

14.008 232 .IS

89.33

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 recalculated, with the result 3.998 for the atoniic weight of this element. JOURNAL, 41, 2881 (1919). J . chim. phys., 16,46 (rgr8). Phys. Rev., IO, 653 (1917).

1 'rHIS

8

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~cuurnweights are given. C = 2 2 . 9 9 7 ; s == 32.069; = 35.457. EXPt.

IV

v VI VI1

Wt. of N a z B O .

Wt. of salt.

At. wt. 3.

0.89853

XaC1 0.52112

IO .896

0.69595

1.59374 I

,86458

XaiSOd 0.63313 NaF 0.29042 Na2S04 0 .4.9113 NazS04 I .r2315 Nan‘Oa 1. . 5 ? 2 5 O

VI11 IX

x IX

IO

At. we.

P.

19.002

.905 19.005

IO

,901

IO

.898

IO.

n9.006

900

10.903 1,99197

o ,83003 NaF

19.004

.60201

0,56757

19.006

I

2.64768

Na&O4 ro.902 I .i2889 Nap I ,10329 NanSQc 10.896 I .86597 Average, IO .goo

19.008 19.005 19.002 19.005

The International Committee on Atomic Weights has adopted this new value for boron. Carbon.--Stahrfoss2 has determined the densities of acetylene, ethylene 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 represent the weight of the liter in grams. In the last column the correction for deviation from Boyle's law is applied. Globe A.

319 58 cc.

Globe B 578 80 cc

I ,17876

I

.I7849 ,17842

I

I I

17905 .I7897

Globe C

893 10 cc.

1 I I

.I7871 .ryg21 . i781.1

Average. I . I 7884

I . 17889

1.17842 Average,

Corrected average.

17926 .I7925 1.17879 I .r7910 I

~

I

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

Globe A .

Globe 9.

I

.26030 ,26177 h ,2603 I

I I

'26031 ,26078

1:

I

I

.zGooz

(I

I

-2.5997 .26183 ,26396)

Average. I I I

.2601g .26146 .26016 Average,

Corrected average. I

,26094

I ,262IO I I

,26096 .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 purified and fractionated. (Globe A. I: I

,35466 3,5400

Globe R .

Globe C.

1.35430 I .35482 I .35416 1.35399

I

.35502

1.3552r 1.35381

Average.

.pi466 .35411 I .354.68 1.35390 Average,

Corrected average.

.35632

I

I

I

I ,3562 I

.35668 1.35585 I .35629 I

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

Globe B.

Globe C.

1.35493 .3.4450 1.35450

1.35459 I .35456 I .35440

.35579 .35525 1.35489 I I

Average.

1.35492 1.35477 1~35460 Average, Average of both series,

Corrected average.

,35684 1.35701 I .35687 I .35690 I .35660 P

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 purifieation and drying the ethylene was fractionally distilled. In the Pol~owing table the correction for deviation from Woyle's law has been applied: Globe KT. 615.23.

Globe 3 . 602 69

L ,26033

I

1.25985 I .26047

I

x

Methad of preparatian. Y

preliminary

,26002

.26041

I

r

.26052

I: .26025

T ,26003

I

.26o31

,26050 ,26037 1.25046

,26045

I

3 3

I ,26029

,26047

1

Y .26052

4 4

1.26012

i

I .26047

I li

Average,

I

26029

Average. I. .26009

I

I .25999 I .25022 i

2

Globe 4 793 70

-___-

--__

I .26022

1.26029

I: .a6031

.26045

I .26021 I ,26050 I I

~

_I_____

I

.26029

.26042

,26032 .26035

-__I_

I

,2603~

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

e

= 11.996

= 11.999

C =

12.005

Argsn.-I,edue2 finds the specific gravity of argon referred to air a t be I .3787$ and the coeRieient of deviation from Boyle's law a t 14' to be IO 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 2 2 0 - - 2 3 0 ° , 3 in chlorine a t 175', 3 in nitrogen a t 90--110' and 5 a t 63-80' in vacuum. In one preliminary experiment 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 Pnternational 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 MolesEiand Reimane o o to

a

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

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

4

33 I

RICPORT 03 COMMITTEE ON ATOMIC WEIGHTS.

+

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 . o o o g ) , 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 iVacuum o n ~ s weights are given. Ag = 107.88;G1 = 55.46.

finds the value of

+

Sample.

........ OQB......... Oa-a... . . . . . . 0&.--.8... ...... TIL,. . . . . . . . . R4........... 04-6.

R&. . . . . . . .

Wt. of YCls.

3.31143 2.31979 2.26815

2.29376 2.00731 r.97610 2.I7949

Ratio. YCls :3 Ag.

Wt. of Ag.

5.47636 3 .83587 3 .7.5045 3.79302 3 .SI977 3.26827 3 .Go389

At. wt.

u.

o .60468 0.60476 0.6047'7 0.60473 o ,60465 o .60463 0,60476

89.32 89.34 89 - 3 5 89.33 89.31 89.30 89.34 Average, 139.33

This value has been adopted by the International Committee on .Atomic Weights. in.---Brauner and Krepelka* have compared tin tetrabromide, distilled in vacuum, with silver. Wt. of BnBrr.

Wt. of Ag.

Ratio, S n B n : 4 Ag.

1.11964 1.97428 2.35469

Preliminary Series. p .or595 r .10206 1 .or579 1.94359 1 .or588 2 31788

5 .1n788 2.46875 0.99510 I .69834 3 442% 3 82180

Final Series. 5.03796 2 .43