70 PROCEEDINGS OF THE AMERICAN ACADEMY 



double tartrate might result, even when the substance would not other- 

 wise be precipitated. How far such an action could have vitiated our 

 previous results, it was, of course, now impossible to determine ; but, as 

 we previously stated, we had always taken great care not to add more 

 than the slightest possible excess of argentic nitrate, and this was es- 

 pecially true in our more recent determinations. Now, however, we 

 were on our guard, and in the following determinations very great 

 pains were taken to add just the requisite amount of the silver salt, 

 and the argentic chloride was subsequently examined for traces of any 

 such occlusion. But, excepting this close attention to well-known 

 precautions, the determinations were inade in the same way as before. 



Analysis of Antimonious Chloride. 



Bringing now the results together, — estimating the amount of oxy- 

 gen by difference, as is usual in chemical analysis, and calculating what 

 would be the composition of a preparation of antimonious chloride in 

 which -^^^xs of a per cent of oxygen had replaced an equivalent amount 

 of chlorine, assuming, of course, Sb = 120 and CI = 35.5, — we obtain 

 the following very striking accordance: — 



Analysis. 85 = 120,^01 = 35.5. 

 Chlorine 46.413 46.418 



Oxygen .213 .213 



Antimony 53.374 53.369 



100.000 100.000 



The general conclusions, then, which we deduce as the results of this 

 investigation, are — 



First, that the value of the atomic weight of antimony found by 

 Schneider in 1856 — Sb= 120.3 — must be accurate within a few 

 tenths of a unit, but that the most probable value of this constant, 

 as deduced from our experiments, is Sb = 120, when S = 32. 



Secondly, that the apparent disagreement with this result, pre- 

 sented by the partial analyses of antimonious chloride, is probably due 



