OF ARTS AND SCIENCES. 65 



ing the course of the experiments that they did not at all represent the 

 total quantity of the oxichloride present in the preparation examined. 

 Not only was the composition of the preparation not materially altered 

 by the slow distillation, — a fiict shown by the determinations marked 

 e in the table on page 40, and by which we were misled at the outset, 

 — but also the product from our distillation yielded when distilled 

 again apparently as much residue as before. In a word, we found the 

 same j^henomena repeated in these distillations at a low temperature 

 which had been so noticeable when the chloride was distilled at its 

 boiling point, and which are so strikingly illustrated by the results 

 given on page 61. It is possible, as before suggested, that the effects 

 might arise from a small additional absorption of water at the succes- 

 sive transfers which the repeated distillations involved ; or, in the later 

 experiments, from the circumstance that the very extensive apparatus 

 employed for drying the carbonic dioxide was not completely effectual. 

 Still, now that our attention had been called to the danger, and we had 

 taken unusual precautions on both these points, the explanations sug- 

 gested did not seem to us sufficient; and we came to the conclusion that 

 the oxichloride must distil over with the chloride of antimony to a cer- 

 tain limited extent, and that it was only an excess above this definite 

 amount which was left behind as residue. Of course, SbOCl not only 

 is not volatile, but is at once decomposed by heat; and we do not sup- 

 pose that this compound by the tension of its own vapor is carried 

 over in distillation. It is a very dilute solution, as it were, of SbOCl 

 in SbClg which thus distils ; and the distillation of the oxichloride 

 may resemble the carrying over of boi-acic acid by the vapor of water, 

 and similar phenomena, the result, as it is has always appeared to us, of 

 a feeble kind of chemical union which has been usually designated by the 

 term "molecular combination." Such a theory vrould account for the 

 remarkable constancy which we have found in the chlorine determina- 

 tions of the various preparations of antimonious chloride purified by 

 distillation. But, on account of the very great difficulty of removing 

 all possible disturbing causes, we found it impossible to obtain a rigid 

 experimental demonstration of our theory without much more time and 

 labor than we could then command. We hope to return to the subject 

 hereafter. Meanwhile, however, it was evident that we could place 

 no reliance whatever on the results just obtained. Nevertheless, the 

 determinations were of value on account of the contrast between these 

 results and those of a similar series of experiments on the residues from 

 antimonious bromide which we collect in the following table : — 



VOL. XIII. (n. s. v.) 5 



