316 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 



sought to fix the ratio between silver and antimonious chloride, and ob- 

 tained results for the atomic weight of antimony quite near to those of 

 Dexter. The SbClg was prepared by the action of dry chlorine upon 

 pure antimony; it is was distilled several times over antimony powder, 

 and it seemed to be perfectly pure. Known weights of this preparation 

 were added to solutions of tartaric acid in water, and the silver chloride 

 was precipitated without previous removal of the antimony. Here, as 

 Cooke has since shown, is a possible source of error, for under such 

 circumstances the crystalline argento-antimonious tartrate may also be 

 thrown down and contaminate the chloride of silver. J>ut be that as it 

 may, Dumas' weighings, reduced to a common standard, give as propor- 

 tional to 100 parts of silver, the quantities of SbClg which are stated in 

 the third of the subjoined columns: 



1.876 grra. SbCl3 = 2.660 grm. Ag. 70.526 



Mean, 70.512, ± .021 



Hence Sb= 121.83. 



In 1861 Kessler's second paper ' relative to the atomic weight of an- 

 timony appeared. Kessler's methods were somewhat complicated, and 

 for full details the original memoirs must be consulted. A standard 

 solution of potassium dichromate was prepared, containing 6.1466 

 grammes to the litre. With this, solutions containing known quantities 

 of antimony or of antimony compounds were titrated, the end reaction 

 being adjusted with a standard solution of ferrous chloride. In some 

 cases the titration was preceded by the addition of a definite weight of 

 potassium chlorate, insufficient for complete oxidation; the dichromate 

 then served to finish the reaction. The object in view was to determine 

 the amount of oxidizing agent, and therefore of oxygen, necessary for 

 the conversion of known quantities of antimonious into antimonic com- 

 pounds. 



In the later paper Kessler refers to his earlier work, and shows that 

 the values then found for antimony were all too high, except in the case 

 of the series made with tartar emetic. That scries he merely states, and 

 subsequently ignores, evidently believing it to be unworthy of further 

 consideration. For the remaining series he points out the sources of 



^ Poggend. .\nnalen, 113, 145. 1861. 



