OF ARTS AND SCIENCES. 53 



snow, and shaken after each addition until the action ceased. As soon 

 as the color of bromine was discharged, the sulphide of carbon was 

 distilled off over a water bath ; and then, replacing the water bath with 

 a gas lamp, the ^romide of antimony was first boiled, and then distilled 

 over the finely powdered antimony which had been added in excess. 

 On account of the high boiling point of bromide of antimony, and the 

 readiness with which its vapor condenses, it was found best in distilling 

 to cover the body of the retort with a hood. The bromide thus pre- 

 pared was purified by repeated distillations over pulverized antimony, 

 as in the case of the chloride, and finally by crystallizing and recrys- 

 tallizing several times from solution in purified sulphide of carbon. A 

 warm saturated solution in sulphide of carbon deposits, when cooled 

 to the freezing point, the greater part of the bromide of antimony in 

 fine acicular crystals. These crystals were dried first with blotting- 

 paper, and then in vacuo over sulphuric acid. The antimonious 

 bromide thus purified by fractional distillation and crystallization was 

 only a very small fraction of the first crude product. It was pure 

 white, had a high silky lustre, and, when first made, was wholly des- 

 titute of odor. It was carefully examined for chlorine, iodine, and 

 arsenic; but the delicate test which we possess for all three of these 

 elements, so frequently associated with commercial antimony and bro- 

 mine, failed to show the least trace of either in the bromide of antimony 

 we analyzed. The determinations of bromine were made in all respects 

 like those of chlorine. Great care was taken not to add more than a 

 very slight excess of argentic nitrate, and we found that under these 

 conditions the supernatant liquid cleared more readily above the pre- 

 cipitate in the case of bromide of silver than with the corresponding 

 chloride, and for this reason the first could be washed more quickly 

 than the last. The results of these determinations are embodied in 

 the table on the following page. 



Here, as before, the letters indicate different preparations : a was 

 made and purified as described above ; b was the same material as a 

 redistilled and again crystallized from bisulphide of carbon ; c was 

 another portion of the same material several times redistilled and twice 

 recrystallized from the same solvent; d was a separate preparation 

 from the start ; e was another separate preparation purified with 

 extreme care. In the last case there was over a kilogramme of the 

 crude product, which was reduced by the fractional distillation and 

 crystallization — each process repeated from ten to twenty times — to 

 the few grammes used in the analyses. These methods of purifying 

 the substance were thus pushed to their utmost limits. 



