OF ARTS AND SCIENCES. 247 



XYII. 



CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF 



HARVARD COLLEGE. 



ON THE CUPRIAMMONIUM DOUBLE SALTS. 



By Theodore William Richards and Hubert Grover Shaw. 



Presented May 10, 1893. 



In the course of an extended investigation upon the ammoniacal 

 compounds of copper, undertaken with the hope of obtaining more 

 light upon the vexed question of their structure, a new class of inter- 

 esting compounds was discovered. The preliminary notice of these 

 compounds was published about a year ago ; * but since that time sev- 

 eral new ones have been added to the list. It is the object of this 

 paper more fully to describe all of these substances, so far as they 

 have been studied. 



The generic feature of the new class is the fact that two different 

 acids — a halogen and an organic acid radical — are united at the 

 same time to the ordinary cupriammonium group. Below are tabu- 

 lated the formulae of the compounds, the preparation, properties, and 

 analyses of which are described in the work which follows : — 



(I.) Cu(NH3)2BrC2H30o. 



(2.) Cu(NH3)3ClC2H30o . H2O. 



(3.) [Cu(NH3)2ClC2H302]2 . 3 NH4C2H3O2 + 7 HoO. 



(4.) Cu(NH3)2BrCH02. 



Besides these compounds two others, which appeared as by-products 

 of the investigation, are worthy of description : — 



(5.) CuCls . 2 NH4C2H3O2. 

 (6.) 3 CuBro . 10 NHs. 



* Theodore W. Richards, Berichte der deutsch. chem. Gesellsch., 1892, p. 1492. 

 Since the publication of this paper, F. Foerste lias announced the discovery of 

 cupriammonium acetate (Ber. d. ch. Ges., 1892, XXV. 3416). 



