104 PROCEEDINGS OP THE AMERICAN ACADEMY 



On examining the residue of the last reaction, before the change was 

 complete, we have observed, mixed with the very brilliant colorless 

 crystals of antimonious oxide, faintly yellow crystals, which had a well- 

 marked monoclinic form, resembling that of the crystals of antimo- 

 nious oxichloride (Sb^OjCU) ; which are deposited from aqueous solu- 

 tions of antimonious chloride which contains a deficiency of tartaric acid, 

 and which we shall describe hereafter. These crystals were only micro- 

 scopic objects, and far too small both in size and quantity for chemical 

 analysis or crystallographic measurement. We were, however, able to 

 prove, both that they contained iodine, and that they were converted 

 into SbjOg, on further heating ; and there can be, therefore, no question 

 that they were crystallized, Sb^OjIj. 



Antimonious Oxibromides (SbOBr and Sb405Br2). 



Under the influence of the air and the direct sunlight, a solution of 

 antimonious bromide undergoes a slow oxidation like that we have 

 just studied, but to a far less extent. Bromine is set free, and an oxi- 

 bromide of antimony is deposited in an amorphous brownish powder ; 

 but the action is so slight, that, even after several weeks' exposure, we 

 were unable to obtain, from a considerable volume of the solution, a 

 sufficient amount of the precipitate for analysis. We were only able 

 to prove that, like SbOI, it is decomposed when heated in two stages, 

 leaving a residue of Sb.^O.; ; but this reaction was sufficient to indicate 

 that it consisted mainly, at least, of SbOBr. The precipitate contained 

 a considerable amount of carbonaceous material, also separated from 

 the solvent by the light ; and it evidently owed its color to this impurity. 

 Pure SbOBr would undoubtedly be colorless. 



The compound Sb^O^Brg can readily be obtained, by heating in a 

 sealed tube, to a temperature of 160", a mixture of antimonious bro- 

 mide and absolute alcohol, according to the method employed by 

 SchaefFer* for preparing the oxichlorides. Some beautifully crystalline 

 oxibromide has been recently prepared in this way by Mr. Clifford 

 Richardson, a student of this laboratory. The crystals were distinctly 

 monoclinic, although too small for measurement. Mr. Richardson's 

 analysis gave the following result : — 



* Berichte der Deutschen Chem. Gesell. 1868. 



