ON THE ACTION OF AMMONIA UPON CUPRI- 

 AMMONIUM ACETOBROMIDE. 



By Theodore William Ricuards and Robert Jay Forsytiie. 



Presented May 13, 1895. 



It is well known that there is a large class of cupriammouium com- 

 pounds which contain two molecules of ammonia for each molecule of the 

 cupric salt. The compounds of this class are -by far the most stable of 

 the cupriammonium compounds ; they are usually permanent in the air, 

 and many of them may be heated above 100° without decomposition. 

 They have, as a general rule, the power of absoi'bing more ammonia if 

 exposed to an atmosphere of this gas ; but the additional ammonia is ex- 

 pelled with the greatest ease. For this reason the compounds containing 

 little ammonia have been assumed in the series of papers of which this is 

 one to be the normal cupriammonium compounds, and any extra ammonia 

 in any other class of compounds has always been designated in the name 

 of this new class. For instance, " tetrammon-cupriammonium bromide " 

 indicates Cu(NH3),Br . 4 NH. or CuBiv . 6 NHg. 



To the class of stable normal cupriammonium compounds belongs the 

 salt Cu(NH3)2BrC2H302, which was recently discovered by one of us.* 

 The possible absorption of more ammonia by this double salt promised to 

 be a question of much interest ; and it is with this question that the 

 present paper is concerned. 



A weighed amount of finely powdered pure cupriammonium aceto- 

 bromide was introduced into a weighed glass tube, so drawn out and bent 

 that the part containing the salt could be immersed in a freezing mixture. 

 Through this tube was passed dry ammonia until the substance, which 

 absorbed a large quantity of gas, remained constant in weight. In two 

 experiments the weights were as follows : — 



(1) (2) 



(2) Weight of substance taken =0.9904 1.4801 



Weight of substance found = 1.2157 1.8090 



Gain in weight 0.2253 0.3289 



* Berichte der deutsch. ch. G,, XXV. 1492. 



