224 THE ATOMIC WEIGHTS. 



was removed by subliming the iodide in an atmosphere of dry carbon 

 dioxide. With this purer material, seven estimations of iodine were 

 made, giving, if Ag = 108 and I = 127, a value for antimony of Sb = 120. 

 Reduced to a uniform standard, Cooke's weighings give the following 

 quantities of Sbig proportional to 100 parts of silver iodide : 



1. 1877 grm. Sljlg gave 1.6727 grm. AgT. 7'. 005 



.4610 " -6497 " 70.956 



3.2527 " 4-5716 " 7'-'50 



1.8068 " 2.5389 " 71.165 



1.5970 " 2.2456 " 7I.II7 



2.3201 " 3-2645 " 71-071 



.3496 " .4927 " 70.956 



Mean, 71.060, dz .023 



Although Cooke's work was practically conclusive, as between the rival 

 values for antimony, his results were severely criticised by Kessler,* who 

 evidently had read Cooke's paper in a very careless way. On the other 

 hand, Schneider published in Poggendorff 's Annalen a friendly review 

 of the new determinations, which so well vindicated his own accuracy. 

 In reply to Kessler, Cooke undertook still another series of experiments 

 with antimony bromide,t and obtained absolute confirmation of his 

 previous results. To a solution of antimony bromide was added a solu- 

 tion containing a known weight of silver not quite sufficient to precipi- 

 tate all the bromine. The excess of the latter was estimated by titration 

 with a normal silver solution. Five analyses gave values for antimony 

 ranging from 119.98 to 120.02, when Ag = 108 and Br = 80. Reduced 

 to a common standard, the weights obtained gave the amounts of SbBr 

 stated in the third column as proportional to 100 parts of silver : 



2.5032 grm. SbBrg = 2.2528 grm. Ag. in. 115 



2.0567 " 1.8509 " III. 119 



2.6512 " 2.3860 " III. 115 



3.3053 " 2.9749 " III. 106 



2.7495 " 2.4745 " 11M13 



Mean, 1 1 1 . 1 14, zh .0014 



Schneider,:}: also, in order to more fully answer Kessler's objections, 

 repeated his work upon the Arnsberg stibnite. This he reduced in hydro- 

 gen as before, correcting scrupulously for impurities. The following 

 percentages of sulphur were found : 



28.546 



28.534 



28-542 



Mean, 28 541, ± .0024 



* Berichte d. Deutsch. Chem. Gesell., 12, 1044. 1879. 



t Amer. Journ. Sci. and Arts, May, 1880. Berichte, 13, 951. 



JJourn. fiir Prakt. Chem. (2), 22, 131. 



