VOL.
XXXIII.
No. 3.
MARCH, 1911.
THE JOURNAL or THE
American Chemical Society EIGHTEENTH ANNUAL REPORT OF THE COMMITTEE OH ATOMIC WEIGHTS. DETERMINATIONS PUBLISHED IN 1910. BY F. W. CLARKE. Received January PO, 1911.
During 1910 a number of important papers on atomic weights have appeared, and their results are summarized in the following pages. A third edition of Clarke’s “Recalculation of the Atomic Weights,” revised and much enlarged, was published by the Smithsonian Institution early in the year. The new data are as follows: Hydrogen.-Atomic weight recalculated by Grinnell Jones1 from all‘ the trustworthy determinations. The value finally deduced is H = 1.00775. That found in Clarke’s recalculation is 1.00779. The two agree to within one part in 25000. Nitrogen.-Guye and Drouginine2 have determined the atomic weight of nitrogen from analyses of weighed quantities of N20,. A spiral of iron wire was heated electrically in the gas, and its increase in weight gave the amount of oxygen contained in the latter. The figures are as follows : Weight Nt04.
0.8856 1 .a494 2. I281 I .719I 0.9951 1.5324 I. 2425
Weight aOp.
Weight Ns.
0.6160 I.2860 I .4801 1 . I957 0.6921 I.0658 0.8642
0.2696 0.5634 0.6480 0.5234 0.3030 0.4666 0.3783
At. n t . N.
14.005
14.019 14.010 14.008 14.010 14*-9 14.008
Mean, %IS
JOURNAL, 32, 513.
J. chim. phys., 8,473.
14.010
GENERAL, PHYSICAL AND TNORGANIC.
262
Clarke's combination of all previous determinations gives IT 14.0101. Richards' value is distinctly lower SzLier clnd Iodine.---The ratio between silver and iodine has been remeasured, with extreme care, by Naxter.' The corrected weights and ratio are subjoined. Ratio hg : I
Weight Ag.
Weight I.
7 ,65468 11.43179 I O . 0857 I
~~.00628
15067 I I. 86648 8.52461 6.42840 8.30266 4.95288 0 .97 I .3 1 y ,3885' 6.56811 18 87136 17.84091 14.95666 I %i.
0.849927 0 ' 849905 0,849933 0,849890 0.849902 0 ' 849897 0 $49909 0 * 849899 0 ' 849897 0.84991I 0.849913 0.849872 o ,849902
7'24498 5.46351 7 .oj641 8' 45901 5.92591 7.97927 5.58231 I6.03902 15.16249 1 2 . 7 I 170
'
Mean, o 849906
This mean, combined with that found by Baxter and Tilley2 for the ratio 2Ag : I,O,, 0.64230, gives Ag = 107.864 and I = 126.913. These values are remarkably low. Lithium.-The peculiar merit of the work done by Richards and Willarda on the atomic weight of lithium, apart from its accuracy, is found in the fact that the ratios measured give values for Ag, C1 and Li which are independent of all previous investigations. Three ratios were measured: LiClO, to LiCl (or 4 0 : LiCl), Ag to LiC1, and AgCl to LiCl. To economize space I omit the " preliminary" series of determinations, and give be€ow only those marked "final." Vacuum weights are given throughout. RATIO4 0 : LiCI. Weight LiClO,
Weight LiC1.
I 2.79265
5 IO9744
10.55416 11.39912
4.20534
EI .
Ratio.
.SO962 I . 50970 1.50969 I ' 50974 I
4,54205 4 45070
17008
17.84842 22.58273
7.11167
I ,50974 I . 50962
8 ' 99846
Mean,
THISJOURNAL, 32, 1603. See 17th Report, Ibid., 31, Ibid., 32,4.
2.57,
258.
I . 50968
REPORT OF THE COMMITTEE ON ATOMIC WEIGHTS.
263
RATIOLiCl : Ag. Wright LiC1.
Weight Ag.
Ratio.
5.82422 6.28664 5.82076 -6.70863 6.24717 7.75349 7.99108
14.82035 15.99687 14.81122 17.07038 15.89620 19,72977 20.33415
0.392988 0.392991 0.392997 0.392998 0.392998 0.392984 0.392988 Mean,
0.392992
RATIOLiCl : AgC1. Weight LiCI.
6.28662 5.82076 6.70863 6.247 I7 5.50435'
8.3452' 6'65987
Weight
AgC1.
Ratio.
2 I . 25442
0.295779 0.295790 0.295791 0.295784 0.295790 0.295779 0.295789
19.67873 22.68030 21.12073 I 8.59600 28.2 1438 22.51564 Mean,
0.295786
From these ratios, combined, Ag = 107.871, C1 = 35.454, and Li = 6.939. The authors regard the value for silver as representing the lower limit for that constant. Calcium.-Atomic weight redetermined by Richards and Honigschmid,2 from analyses of calcium bromide. Two ratios were measured, with the following results. Vacuum weights are implied. Values calculated with Ag = 107.88, Br = 79.916. RATIOCaBr, : zAg. Weight CaBr2.
Weight aAg.
4.20860 4.58644 5 ' 34866 7.23724 4.67673 7.41636
4.54252 4,95025 5.77301 7.81126 5.04779 8.043455
At. wt. Ca.
40.068 40.071 40.068 40.073 40.068 40.074 Mean,
40.0703
Scheuer, J . chim. phys., 8, 289, discusses the atomic weight of chlorine as deduced from the density of HCI. The paper is practically a reproduction of one cited last year. Hinrichs, Comfit. read., 151, 513, argues that Ag = io8 exactly. JOURNAL THIS JOURNAL, 32, 1577. A second paper by the same authors is in THIS for January, 1911.
GENERAL, PHYSICAL AND INORGANIC.
264
RATIO CaBr, : 2AgBr. Weight CaBt?.
At. wt. Ca.
Weight zAgBi
1Sg9r 7.92400 6.78048 6.45970 5 95390 5 15998
19.13778 14.88810
IO.
40.073 40.072 40.072 40.070 40.067 40.067
12.73961 12.13702 II.
18684
9 .Go513
Mean,
40.0702
W h y this determination, which confirms the earlier work of Richards, should be so much lower than that of Hinrichsen is unexplained. The new work is probably to be preferred. StmntizLm.-Thorpe and Francis' have redetermined the atomic weight of strontium by several distinct methods. The corrected weights are given in the following summary of results: RATIO SrBr, : 2Ag. Weight SrBr?.
Ratio,
Weight 2Ag.
1.77884 I . 86109 1.85254 I . 73801 1.85787 1 .70563
1.1471 I. I470
1.55073 1.62260 1.61511 1.51534 1.61994 1 ,48707
I. I470 I. I470
I. 1469 I. I470
Mw,
1.1470
Hence Sr = 87.645RATIO SrBr, : zAgBr. Weight SrBr?.
Ratio.
Weight aAgBr.
.86112 I .a5261 1 * 73807 1.85798 1.70571
2.82438 2.81155 2.63762 2.81999 2.58866
I
0.65895 0.65893 0.65895 0.65886 0.65892 Mean,
HenceSr
=
RATIO SrCl, :
2Ag.
Weight SrCl?.
Weight zAg.
I .64759
2.24203 2.26356 2 .os817 2.24011 2.39486 2. I2572
I . 66352
53462 .64619 I .76m6 I . 56224 1
0.65892
87.653.
~
I
Hence& = 87.642. ' PToC.ROY,Soc., 83 (A), 277.
Ratio,
0.73486 0.73491 0.73491 0.73487 0.73493 0 * 73492
REPORT OF THE COMMITTEE ON ATOMIC WEIGHTS.
265
RATIOSrCl, : 2AgCI. Weight SrCI,. 1 a64764
I * 66357
53467 I . 64624 I .76010 1*
Weight zAgC1.
Ratio.
2.97899 3.00762 2.77416 2.97653 3.18202
0 * 55309
0.55312 0.55314 0.55307 0.55314 Mean,
0.55311
HenceSr = 87.645.
Supplementary determinations were made by determining the ratios SrBr, : SrSO,, and SrC1, : SrSO,, as follows: RATIO SrBr, : &SO,. Weight SrBrz.
7 * 14570 7.64281 9.86072
Weight SrS0+
Ratio
5 * 30466 5 e67326 7 * 32047
1.3471 1* 3472 1 3470
-
Mean,
1.3471
Hence Sr = 87.629. RATIOSrCI, : SrSO,. Weight SrCls.
7 30246 8.71628 8'46493 8'79502
Weight SrSO,.
Ratio.
8.4607 I 10.09868 9.80743 I O . 189.59
0.86310 0.86311 0.86311 0.86314 Mean,
0.863115
Hence Sr = 87.661.
The authors adopt 87.65 as their final value, after discussing the relative merits of the several ratios. The calculations are based upbn Ag = 107.88, C1 = 35.46, Br = 79.916, and S = 32.07. Mercwy.--Easley' has continued his research upon the atomic weight of mercury, the first part of which was noticed last year. Mercuric chloride was analyzed by electrolysis, giving the subjoined results. The weights are reduced to a vacuum, and the calculations are based upon C1 = 35.46. PRELIMINARY SERIES. Weight HgClr.
10.05743 8.41289 10.99056 IO. 28282 19.57120
Weight H g .
At. wt. H g .
7.43123 6.21687 8 . I 1897 7.59681 14.46032
200.
200.52 200.58 200.65 Mean,
THISJOURNAL,
32, 1117.
68
200.71
zoo.63
266
GENERAL, PHYSICAL AND INORGANIC.
PISALSERIES. Weight HgCI:.
Weight Hg"
8.14695 I I .03881 13.48 192 I I . 08026 11.31231 21.44026
6 . or909
At. wt. Hg.
200.61 200.64 200.66 200.60 200.66 zoo. 62
8.15592 9.96129
8.18610 8.35819 x j .a4060
Mean,
200.63
This soniirms the previous work, and seems to prove that the heretofore accepted value for mercury is too low.
[email protected] weight redetermined by Baxter and Jones' from analyses of silver phosphate. Weight AgsPO4.
6.02166 6.35722 5.80244 5.05845 3'34498 7,15386 7.20085 6.20182 5.20683
Weight 3AgBr.
Ratio.
8.34490 8.55419 7.80819 6.80685 3,43544 (AgC1) 9.62694 9.68947 8.34522 7 ,00605
Mean,
I . 34562
In experiment 5 the silver was weighed as chloride, but recalculated to bromide in the ratio. With Ag = 107.88, P = 31.043. Vanadium-Prandtl and Bleyer, whose work on the atomic weight of vanadium was noticed in my report for 1 9 9 , have published a second memoira 'on the subject. Eight new analyses of vanadyl trichloride are given, of which four are rejected as defective. The four satisfactory determinations follow, with vacuum weights, and the ratio 3AgCl : VOCl, : :
Io0
: x.
Weight VOCI,.
Weight 3AgC1.
Ratio.
7.77585 8.4 I904 10.66137 5.53998
19.26836 20.86554 26.42699 13.73492
40.301 40.311 40.321 40.333
Xean,
V
40.3 165
From these figures, combined with the earlier series, the authors deduce = 51.061, f0.024, when Ag = 107.880 and C1 = 35.460. Prandtl and Bleyer also investigated the ratio V,O, : V,O,, by reTHISJOURNAL, 32, 298. 2.anurg. Chem., 67, 257.
=PORT
OF THE COMMITTEE ON ATOMIC WEIGHTS.
267
duction of the pentoxide in hydrogen. Their determinations, with vacuum weights, appear in the next table. Weight VlOs.
Weight VzOa.
At. w t . V.
9.11431 9.85727 8.70923 12.26426
7.51639 8.13127 7.18456 10.11721
51.261 51.376 51.395 51.394
Mean,
51.3565
Although these determinations agree with Roscoe’s, the authors regard them as doubtful. Their VOCI, determinations are preferred. The work of McAdam2 on this constant consisted in reducing NaVO, to NaCl by heating in dry HC1. With vacuum weights, and NaCl = 58.46, the following results were obtained: Weight NaVOa.
4.8564 5.6404 4.4263 5.7805 9.4902
At. w t . V.
Weight NaCi.
2,3277 2.7033 2.I220 2.7710 4.5478
50.966 50.976 50.946 50.952 50.997
Mean,
50.967
Taking into consideration the determinations of Prandtl and Bleyer, the atomic weight of vanadium may be rounded off to 5 I. TantaZum.-Balke’sS determinations of the atomic weight of tantalum are based upon the hydrolysis of the pentachloride. With vacuum weights and C1 = 35.46, the final results are as follows: Weight TaClh
12.99680 9.24957 IO. 17456 17.99542 I I. 70558 6.24767 7.26375 15.88270
At. a t . Ta.
Weight Ta205.
8.02326 5 .71 104 6.28133 I I. I 1014 7.22693 3.85658 4.48398 9* 80465
181.49 181.60 181.52 181.55 181.55 181.46 181.48 181.49 Mean,
181.52
The rounded-off number 181.5 is to be accepted. Tellurium.-Marckwald and Foizik, by a complex volumetric process, find for this atomic weight the value 127.61. The data are. too bulky and complicated for reproduction here. The purpose of the investigation The authors give 51.374. 32, 1603. a Ibid., 32, 1127. Ber., 43, 1710.
* THISJOURNAL,
268
GENERAL, PHYSICAL AND INORGANIC.
was not so much to determin the atomic weight exactly, as to ascertain the cause of the low value found in several previous researches. Flint' has continued the work reported by Browning and Flint in 1909 on the fractionation of tellurium by hydrolysis of the tetrachloride. The unfractionated material, by the basic nitrate method, gave Te = 127.45. Progressive diminution of the atomic weight was noted in a series of fractions, namely the fourth, eight and tenth. The tenth gave low atomic weights as shown in the following table: Weight Te2HKOj
2.06311 2.18903 3.56161 2.9982 x 2.86977 2.47403 4.85363
Weight TeO
.71688 1.82172 2.96446 2.49537 2.38824 2.05898 4.03943 I
At. wt. Te.
124.25
124.27 124.42 124.37 124.27 124.31 124.32
Mean, 124.32
The investigation is still in progress; but the present results are promising, and seems to show that ordinary tellurium is really a mixture. If that should be proved, all former determinations of the atomic weight would go for nothing. Scadizcm.-Preliminary determinations of the atomic weight of scandium, by the sulfate method, are given by Meyer and Winterla but without the detailed weighings. The values found for Sc range between 44.86 and 45.37; in mean, 45.12. This is much higher than the accepted value. Neodymium-B y very careful analyses of neodymium chloride, Baxter and Chapid have determined the atomic weight of the metal. Two ratios were measured, with vacuum weights, and reduced with Ag = 107.880 and C1 = 35.457. Weight NdC13.
4 . 2 7402 2.79574 2.77391 3.42064 4.11855 3.95958 4.64435
~ T I NdCl, O : 3Ag. Weighi 3 A g .
5.5'855 3.61030 3.58196 4.41695 5.31786 5.11289 5.99699
At wt. Nd
283 144.249 144.259 144.267 144.280 144.266 144.271
I&.
Mean, 144.268 Am. J . Sci., [4] 30, 209. 2.enorg. Chem., 67, 398. Proc. Am. Aced., 46, 215 (1910); reproduced in THISJOURNAL for January, igrr.
REPORT OF THE COMMITTEE ON ATOMIC WEIGRTS.
269
RATIONdCl, : 3AgCl. Weight NdCla
Weight 3AgCI.
At. wt. Nd.
3.16218 2 * 93305 2 e99149 2.62468 2 * 38439 2 -55827 3.591 I 4 4 * 27402 4 * 69459 2 m79.574 2.59810 3.42064 4.11855 3.95958 2.7'834
5.42546 5.03226 5.13195 4.50338 4.09064 4.38891 6.16095 7 * 33203 8.05444 4.79630 4.45741 5.86872 7.065181 6 79345 ; 4 66395
144.257 144.262 144-289 144.250 144.278 144.280 144.277 144.293 144.264 144.280 ,144.270 144.265 144.298 144.262 144.257
Mean,
144.272
A slight correction for a little unseparated praseodymium raises the value to 144.275. This is doubtless the best determination of the constant yet made. Er&iuwz.-Hofmann,' by analyses and syntheses of the sulfate, has made three new determinations of the atomic weight of "neoerbium." Weight B%O8.
Weight sulfate,
0.3117 0.4486 0.3718
0.5070 0.7296 0.6048
At. wt. Er.
Weight ErPOI
0.3117 0.44863 0.3718
167.67 167.73 167.64
Mean,
167.68
The oxide in the first column was converted into sulfate, which, on calcination, gave the oxide of the third column. Calculated with S = 32.07. The Helium-Argon Grou15.-Watsona has determined the weight of a normal liter of helium as 0.17814and 0.17830gram. Hence He = 3.994. For .neon, eleven determinations of the normal liter ranged from 0.8997 to 0.9006 gram; in mean, 0.9002. This, by the method of limiting densities, gives Ne = 20.200. By the same method Watson3 has reduced the densities of krypton and xenon, as measured in 1908 by Moore.' The final values are Kr = 82.92 and Xe = 130.22. The density of argon has been redetermined by Fischer and Hahnel.6 Ber., 43, 2635. J. C h .SOC.,97, 810. ' . I b d . , 973 833. Proc. Claem. SOC.,24, 273. Bw-s 431 1435.
2-r
GENEFUL, PHPSICAL .ZND INORGANIC.
t
The mea11 < s i
sex en dclermination~is
1
o 945, referred t o 0
-
IS.
Hence
m d Gray,' hy mean5 of the microbalance, have been able to n-cigh the gaseoiis emanation of radium, for which they propose the name rizfuir ['lie l a h e \ thuq iound for i t 5 molecular weight are 3 2 2 , 216, 2 2 7 . L J sa11 7 , in mean 2 2 0 The same \ aliie wa? also found by Debierne2 by a different method l h w o u \ ,Y.'oteA.--Richards and 13axterd have investigated the of density corrections, or in other words the reduction of weights to :L \ acuunt. 'I'hey regard the validity of the corrections, as applied a t Hail ard, rli well established. Relation5 between the atomic weights ha\ e been studied by Howard.4 Dubreui13 has continued his recalculation of the determinations of Stas. - .____.I_
[COATRIBLT~ONS FROM THE CHEMILU. LABORATORY OF HARVARD COLLEGE.]
THE ULTRAVIOLET ABSORPTION SPECTRUM OF AQUEOUS SOLUTIONS OF NEODYMIUM CHLORIDE. BY GREGORYPAULBAXTERA N D T R U X A N STEPHEN WOODWARD Received December
22
rgia
111 a recent paper upon the atomic weight of neodymiuma the absorption spectrum of aqueous solutions of neodymium salts from i, 7000 to / 41100 is described After the earlier measurements were made a large
quartz spectrograph became available. and with this instrument the ultra\-iolet absorption spectrum of aqueous neodymium chloride has been examined The spectrograph was constructed by R. Fuess, Berlin. I t has lenses j cm. in diameter, provided with diaphragms, and of about 80 cm. focal length. while the 60' Cornu prism is of 5 cm. base and 4 . j cm. high. In ordei to avoid as far as possible difficulty from double refraction the diameter of the lenses was diminished one-half with the diaphragms. Bv means of a serles of trial negatives, with the spark of a cadmium alloy for illumination, the prism was set in the position of minimum d e k t i o n for approximately A 3400, and the positions of the collimating and camcra lenses were so adjusted that the region A 2 5 0 0 to A7500 was in fair focus throughout. Owing to the curvature of the spectrum image, i t \t a\ 1101 possible to h a w a wider range in fc cus a t any one time. Howr, this range included the whole of the best continuous spectrum Mhich TI e were able to produce. owzpr v , * i d , 151, 1 2 6 Ibzd., 150, 1740. xlnr-,JOI-RXAL, 32, 507 ( hi.?n -\m)r, 101, 181,265 ~ { I U . ' w c c h m , (417, 119 Easter and Chapin, Proc. -4m.,icad., 46,
I (
-"P,
215
(19x0);THISJOURNAL, 33, 13.
