320 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 



Schneider analyzed a sulphide of antimony which was already formed. 

 Cooke, reversing the method, effected the synthesis of this compound. 

 Known weights of pure antimony were dissolved in hydrochloric acid 

 containing a little nitric acid. In this solution weighed balls of antimony 

 were boiled until the liquid became colorless; subsequently the weight 

 of metal lost by the balls was ascertained. To the solution, which now 

 contained only antimonious compounds, tartaric acid was added, and 

 then, with a supersaturated aqueous sulphhydric acid, antimony trisul- 

 phide was precipitated. The precipitate was collected by an ingenious 

 process of reverse filtration, converted into the black modification by 

 drying at 210°, and weighed. After weighing, the SbgSg was dissolved 

 in hydrochloric acid, leaving a carbonaceous residue unacted upon. This 

 was carefully estimated and corrected for. About two grammes of 

 antimony were taken in each experiment and thirteen syntheses were 

 performed. In two of these, however, the antimony trisulphide was 

 weighed only in the red modification, and the results were uncorrected 

 by conversion into the black variety and estimation of the carbonaceous 

 residue. In fact, every such conversion and correction was preceded by 

 a weighing of the red modification of the SbaSg. The mean result of these 

 weighings, if 8 = 32, gave Sb = 119.994. The mean result of the cor- 

 rected syntheses gave Sb = 120.295. In these eleven experiments the 

 following percentages of S in SbjSg were established : 



28.57 

 28.60 

 28.57 

 28.43 

 28.42 

 28.53 

 28.50 

 28.49 

 28.58 

 28.50 

 28.51 



Mean, 28.5182, ± .0120 



Hence Sb = 120.55. 



These results, confirmatory of the work of Schneider, were presented 

 to the American Academy in 1876. Still, before publication, Cooke 

 thought it best to repeat the work of Dumas, in order to detect the cause 

 of the old discrepancy between the values Sb = 120 and Sb = 122. Ac- 

 cordingly, various samples of antimony trichloride were taken, and puri- 

 fied by repeated distillations. The final distillate was further subjected 

 to several recrystallizations from the fused state; or, in one case, from a 



