NOVEMBER,1915.
Vot. XXXVII.
No.
11.
THE.JOURNAL OF THE
American Chemical Society with which has been incorporated the
American Chemical Journal (Founded by Ira Remsen)
ANNUAL REPORT OF THE INTERNATIONAL COMMITTEE ON ATOMIC WEIGHTS, 1916. Received September 13, 1915.
Although many scientific activities have been interrupted by the European war, a fair number of atomic-weight determinations have appeared since the report for 1915 was prepared. They are, briefly, as follows: Carbon.-Richards and Hoover' neutralized sodium carbonate with hydrobromic acid which had been standardized against silver. In this way the ratio of carbonate to silver was determined. With Ag = 107.88, Br = 79.916 and Na = 22.995, C = 12.005. Sulfur.-Atomic weight also determined by Richards and Hoover,? who measured the ratio between sodium carbonate and sulfate. With the values previously assigned to sodium and carbon, S = 32.060. Iodine.-By the direct analysis of iodine pentoxide, Guichard3 finds I = 126.92. Copper.-The electrolytic ratio between copper and silver has been remeasured by S h r i m p t ~ nwith , ~ Ag = 107.88, Cu = 63.563, as the mean of ten determinations. 1
2
THISJOURNAL,
37,95
Ihid , 37, io8 Compt r e n d , 159, 185. Pioc Phys S o c London, 26, 292
2450
ISTEKNATIONAL COMMITTEE O X ATOMIC WEIGHTS,
19I 6.
Nickel.-Oechsner de Coninck and Gerard, by reduction of nickcl oxalate in hvdrogen, firid X I = 58.57. Few details are given. Cadmium.--By the electrolysis of cadmium chloride Baxter and Hartmanil' find Ccl = I I ~ . . L I ~ . This confirm.; the carlicr work of Baxter am1 hii colleagues, and gives radniiuni a much higher r a l u e than was iound hi- i i u l e t t . Mercury.- By the synthesis of mercuric bromide Baker and Watson3 find Iig = 1 0 0 . ~ 7 , when I3r = 79.92. 'Chis value i i near that found by Easle?. Lead.-By the analysis of lead bromide Baxter and Thorvaldsen4 find Pb = 207.19. With the chloride, Baxter and Grover6 obtained the value 2 0 7 . 2 I , and with the bromide, 207.19. These determinations were made n ith no?i ~ i l lead l from widely separated and dissimilar sources, and are highly concordant The value Pb = 207.20 will be adopted in the table of atomic weights, Lead from radioactive minerals, however, has been found to differ in atomic weight from ordinary lead. For lead from thorite Soddy and IIyma:iR found atomic weights ranging from 208.3 to 208.5. Maurice Curie' studied lead from pitchblende, carnotite, and yttrotantalite, and obtained values from 206.36 to 206.64. Lead from monazite and galena was more nearly normal. Honigschmid and Horowitzs studied lead from pitchblende, and by analyses of the chloride found Pb = 206.735. Richards and Lembertg made six series of analyses of lead chloride prepared with lead derived from carnotite, thorianite, pitchblende and uraninite, the mean values being Pb = 206.59, 206.81, 206.83, 206.57, 206.86, and 206.36. These figures, although each series is concordant within itself, show that radio lead is variable in its atomic weight, and that the single, definite metal is yet to be completely isolated. Indeed, the relations between radio lead (or leads) and ordinary lead are still obscure. Tin.-Briscoe,'O by analyses of the tetrachloride SnC14 finds Sn = I 18.70, when Xg = 107.88 and C1 = 35.457 This new value, which was determilied with all modern precautions, will be adopted in the table. Tantalum.-Sears and Ralke, in a preliminary series of determinations Compt r e n d , 158, 134j ' 'rF?rs JO'URKAL, 37, I I 3 .l C'IpevI S o c , 107, 63
'
T I I I G JOURK4L,
' TbTd,
37,
1027
37,
If121
INTERNATIONAL COMMITTEE ON ATOMIC WEIGHTS, I 9 16.
245 1
of the ratio between Tach and Ag, obtained values for T a ranging between 180.90and 182.14.The research is to be continued. Praseodymium.-Baxter and Stewart,' in a long series of concordant analyses of the chloride PrCla, find Pr = 140.92. The rounded-off figure 140.9will be adopted here. INTERNATIONAL ATOMICWEIGHTS,1916. Symbol.
Atomic weight.
Symbol.
27.1
96.0 144.3
120.2
Arsenic. . . . . . . . . . . .As Barium.. . . . . . . . . . .Ba Bismuth. . . . . . . . . . .Bi Boron.. ........... . B
39.88 74.96 137.37 208.0
20.2
Nickel..
. . . . . . . . . . . . . . . . . ..Ni
. . . . . . . . . . . . . . . . .N
79.92 112.40
52
Copper.. ...........Cu Dysprosium. . . . . . . .Dy Erbium. . . . . . . . . . . .Er Europium. . . . . . . . ..Eu Fluorine, . . . . . . . . . . .F Gadolinium. ........ Gd Gallium.. . . . . . . . . . .Ga Germanium. ........Ge Glucinum. . . . . . . . . .G1 Gold Au Helium. . . . . . . . . . . . H e Holmium.. . . . . . . . . .Ho Hydrogen.. . . . . . . . . H Indium. . . . . . . . . . .. I n Iodine. . . . . . . . . . . .. I Iron.. . . . . . . . . . . . .. F e Krypton.. . . . . . . . . .Kr
Lutecium.. . . . . . . . ..Lu Magnesium. ........Mg Manganese.. ........Mn Mercury. . . . . . . . . .. H g 1 THIS JOURNAL, 37,
Platinum. . . . . . . . . . . . . . . . . . .Pt Potassium. . . . . . . . . . . . . . . . .K
.o
58.97 93.5 63.57 162.5 167.7 152.0 19.0 157.3 69.9 72.5 9.I 197.2
58.68 222.4
Nitrogen.
I1 .o
132.81 40.07 12.005 140.25 35.46
Atomic weight.
. . . . . . . . . .Sa Scandium. . . . . . . . . . . . . . . . ..Sc Selenium. . . . . . . . . . . . . . . . . ..Se Silicon.. . . . . . . . . . . . . . . . . . ..Si Silver . . . . . . . . . . . . . . . . . . . . .Ag
4.00 163.5 I ,008 114.8 126.92 193.1 Tungsten. . . . . . . . . . . . . . . . . .W 584 82.92 Uranium. . . . . . . . . . . . . . . . . . . U 139.0 207.20 Xenon ........ . . . . . . . . .Xe 6.94 Yttrium. . . . . . . . . . . . . . . . . . ..Yt 175.0 Zinc: ..................... .Zn 24.32 Zirconium Zr 54.93 200.6 5 16.
14.01 190.9 16.00 106.7 31.04 195.2 39.10 140.9 226.0 102.9 85.45 101.7 150.4 44.1 79.2 28.3 107.88 23 .oo 87.63 32.06 181.5 127.5
159.2 204.0
232.4 168.5 118.7 48.1 184.0 238.2 51 .o 130.2 173.5 88.7
65.37 90.6
2452
JOEL H. HILDEBRAND AND ERMON DWIGHT EASTMAN.
Ytterbium.-Blumenfeld and Urbain,? in a series of analyses of the sulfate Ube(SOl)&3H20, find 3% = 173.54. This may be rounded off to 173.5. Uranium.-Honigschmid, from analyses of the bromide UBr4, finds U = 238.18. The value 238.2 may properly be adopted. At the meeting of the International Congress of Applied Chemistry, in 19x2, a resolution was passed favoring delay in changes in the table of atomic weights. In accordance with the desire so expressed, no changes have since been made, but several now seem to be necessary. These relate to C, S, He, Sn, Pb, Ka, LT,Yt, Pr, Yb, Lu, and U. The reasons for the changes, which are small, may be found in this and the three preceding reports. They are based upon new determinations, which seem to be better than the old. (Signed) F. W. CLARKE,
T. E. THORPE, W. OSTWALD. NOTE.-Professor Urbain, because of an official connection with the military service of France, is debarred from signing any international report during the war. Otherwise he would approve this report. F. W. C. [CONTRIBUTION FROM
THE
CHEMICAL LABORATORY OF THE UNIVERSITY OF CALIFORNIA. ]
THE VAPOR PRESSURE OF THALLIUM AMALGAMS. B Y JOSL H HILDEBRAND AND ERYON DWIGHT EASTMAN. Received September 3, 1915
The work presented in this paper is in continuation of the series of investigations undertaken by one of us on the laws of concentrated solutions. The previous papers include vapor pressure measurements on zincI3silver,*gold,*and bismuth? amalgams, and also a discussion of e. m. f. measurements to be found in the literature on the amalgams of zinc, tin, lead, thallium, indium and cadmium.l We would refer to the earlier papers for the progress of the work up to this point, as well as for references t o the literature. The experimental procedure was essentially the same as that used in working with bismuth amalgams, so that it is unnecessary to repeat its description here. The thallium used was analyzed for lead, two experiments giving 0 . 3 % and o.2jyo, respectively, an amount of impurity far too small to have any effect on these measurements. 1 2
Compt. rend., 159,325. 2.Electrochem., 20, 452.
3 J. H. Hildebrand, Orig. C m m . 8th Intern. Congr. Appl. Chem., 2 2 , 139, 147; Trans. A m Electrochem. SOL, 2 2 , 319,335 (1912);THISJOURNAL, 35, 501 (1913). 4 Ermon D.Eastman and J. H Hildebrand, THISJOURNAL, 36, 2020 (1914).
