RICHARDS AND MERIGOLD. — BROMIDES AND SULPHOCYANATEIS, 133 



IV. 0.3191 gram of substance yielded 0.3732 gram of argentic bromide. 

 V. 0.3045 gram of substance yielded 0.3576 gram of argentic bromide. 



2. COPROSAMMONIUM SuLPHOCTANATE, Cu.2(NH3)2(SCN)2. 



In the first place, cuprous hydrate was prepared by adding an excess 

 of a solution of sodic hydrate to cuprous chloride. The precipitated 

 hydrate was washed once or twice and dissolved in the least possible 

 amount of ammonic hydrate solution. On the addition of a concentrated 

 solution of ammonic sulphocyanate, cuprosammonium sulphocyanate is 

 precipitated as a white crystalline powder. Attempts to obtain larger 

 crystals by using more dilute solutions were unsuccessful. The substance 

 was washed with alcohol and ether, and dried rapidly by pressing be- 

 tween filter paper. Owing to the finely divided state in which the sub- 

 stance comes down, it is very difficult to dry it thoroughly and quickly 

 in this fashion. It cannot be dried by exposure to the air, or over 

 sulphuric acid, on account of the readiness with which it loses ammo- 

 nia. Hence the analytical results are somewhat low on account of the 

 presence of traces of moisture. The only remarkable property of 

 this compound is its instability. Most of the other compounds of 

 copper containing two molecules of ammonia are extremely stable, some 

 of them retaining all their ammonia even at 100°. The cuprosammo- 

 nium sulphocyanate, however, loses ammonia rapidly even at ordinary 

 temperatures. 



In many samples which had been allowed to stand for some time, 

 the sulphocyanic acid also was found to be deficient. The two analyses 

 given below are those of the two freshest preparations, and even they 

 leave much to be desired in the way of accuracy. It is possible that 

 the molecular rearrangement caused by the loss of the ammonia may 

 induce an especial tendency toward oxidation, which, combined with 



