RICHARDS AND WHITRIDGE. — CUPRIAMMONIUM SALTS. 461 



substance in a state of purity, as iu the previous instance, but rather 

 to the great difficulty of drying the substance enough without drying 

 it too much. The extra molecule of ammonia and the molecule of 

 water are held very loosely, mere exposure to the air allowing thera 

 to escape. Especially is this the case when the substance is placed 

 over sulphuric acid. 0.1242 gram of material, which had been ex- 

 posed thus until constant iu weight, yielded 0.0331 gram, or 26.65 per 

 cent, of copper upon electrolysis. This showed that the substance had 

 lost practically all of its extra ammonia and water, for the theoretical 

 per cent of copjDer in Cu(NH3)2BrC2H302 is 26.87. The new salt 

 consists of pearly flakes of a brilliant light blue color, somewhat less 

 intense than that of the normal cupriammonium acetobromide. It is 

 only very slightly soluble in alcohol, and is at once decomposed by 

 water, a little of the copper going into solution. In properties and 

 general appearance it resembles the ammon-cupriammonium aceto- 

 chloride prepared by Richards and Shaw, except that it is much less 

 stable. 



The acetic acid was determined by distillation with phosphoric acid, 

 according to the well known method of Fresenius. Ilydrobromic and 

 a trace of phosphoric acid which come over in the distillate were pre- 

 cipitated with argentic nitrate from the neutralized solution, the result 

 being calculated as argentic bromide, since this is the greater part of 

 the precipitate. 



Analyses of Cu (NH3) jBrC JI3O2 . H2O. 



I. 0.3276 gram of the substance yielded 0.0774 gram of copper 

 upon electrolysis. 

 II. 0.3902 gram of the substance yielded 0.0896 gram of copper 

 upon electrolysis. 



III. 0.3376 gram of the substance yielded 0.2365 gram of argentic 



bromide. 



IV, 0.2453 gram of the substance yielded 0.1732 gram of argentic 



bromide. 

 V. 0.4214 gram of the substance yielded 0.2940 gram of argentic 

 bromide. 

 VI. 0.2600 gram of the substance distilled with caustic potash re- 

 quired 13.28 cubic centimeters of a decinormal acid solution 

 for neutralization. 

 VII. 0.1528 gram of the substance distilled with caustic potash re- 

 quired 16.29 cubic centimeters of a decinormal solution for 

 neutralization. 



