294 SMITJISONIAN MISCELLANEOUS COLLECTIOXS VOL. 5-i 



One other nietliod of <letc'niiin;Ui<)ii Tor llie atomic weiirlit of tin was 

 employed by Bongartz and Classen. Electrolytic tin was converted into 

 snlphide, and the sulphnr so taken np was oxidized by means of hydrogen 

 peroxide, by Classen's method, and wciiiiied as barium sidpliate. The 

 results, as given liv tlie authors, aic suhjoined : 



8)1 taken. Per cent, of 8 gained. 



2.G285 53.91 



.7495 53.87 



1.4785 53.94 



2.5690 53.94 



2.1765 53.85 



1.3245 53.88 



.9897 53.83 



2.7160 53.86 



Mean, 53.885, ± .0098 



This percentage of sidphur. liowever, was computed from weigliings 

 of barium sulphate. What values were assigned to the atomic weights 

 of barium and sulphur is not stated, but as Meyer and Seubert's figures 

 are used foi' other elements throughout this pa])er, we may assume that 

 they apply here also. Putting 6 = 15.96, S = 31.98, and Ba = 136..Sf;. 

 the 53.885 per cent, of sulphur becomes 392.056, ±.0713 of BaSO^, the 

 compound actually weighed. This gives us the ratio — 

 Sn:2BaS0,: : 100: 392.056. ± .0713 



as the real result of tlie experiments, from whicli, witli the later values 

 for Ba. S and 0, the atomic weight of tin may be calculated. 



A single determination of the atomic weight of tin, made l:)y Schmidt,' 

 ought not to he overlooked, although it was only incidimtal to liis research 

 upon tin sulphide. Tn one experiment, 0.5243 grm. Sn gave 0.(i(i59 

 SnOo. Hence Sn = 118.49. This lies about midway between the two 

 sets of values already computed. 



We now have, for tin, the following availal)le ratios: 



( 1) . Sn : SnO, : : 100 : 127.070, ± .0026 



(2). 4 Ag:SnCb:: 100: 60.207, ± .0060 



(3). Percentage of tin in SnBr,, 27.123, ± .0020 



(4). Percentage of tin in K,SnCl,-„ 29.040, ± .0021 



(5). Percentage of tin in Am.SnCl,,, 32.369, ± .0088 



(6). Sn:2BaS0,: : 100: 392.056. ± .0713 



The values to use in reducticm of these ratios are — 



Ag =107.880, ±.00029 N = 14.0101, ± .0001 



CI = 35.4584, ± .0002 S = 32.0067, ± .00075 



Br = 79.9197, ± .0003 Ba = 137.363, ±.0025 



H = 1.00779, ± .00001 



' Berichte, 27, 2743. 1894. 



