254 PROCEEDINGS OF THE AMERICAN ACADEMY 



tain 25.8 per cent of copper and 14.35 of chlorine. Since the theoreti- 

 cal percentages corresponding to Cu(NH) 2 ClC 2 H 3 2 are respectively 

 33.08 and 18.45, it is clear that the excess of amnionic acetate had not 

 been wholly decomposed during the long exposure. Further experi- 

 ments in this direction will be made in the near future. 



Results. 



4. Cupriammonium Formibromide, 

 Cu(NH 3 ) 2 BrCH0 2 . 



Cupriammonium formibromide is made after a method essentially 

 similar to that employed in making the corresponding compound of 

 acetic acid. The salt is more difficult to obtain in a pure state ; but 

 any reasonably concentrated solution containing bromine, copper, much 

 formic acid, and ammonia in very slight excess, will deposit the deep 

 "robin's egg" blue crystals of the desired salt upon the addition of 

 alcohol. The possibility of the formation of basic salts of copper is 

 diminished if the excess of ammonia is added after the addition of the 

 alcohol. The salt possesses no unexpected properties, except that the 

 color of the short needles is much less brilliant and crude than that of 

 cupriammonium acetobromide. 



A similar compound containing chlorine instead of bromine has been 

 prepared, and analyzed with results which were sufficiently accurate to 

 show the identity of the compound ; but it was thought desirable to 

 study more carefully the conditions necessary for its preparation in a 

 pure state before publishing the results. Moreover, a more complex 

 formibromide of most interesting aspect and composition has been 

 made. This substance also awaits further study. 



Analyses of Cupriammonium Formibromide. 



I. 0.2192 gr. of the substance gave on electrolysis 0.0621 gr. of 



copper. 

 II. 0.2164 gr. of the substance yielded on electrolysis 0.0618 gr. 

 of copper. 



