78 PROCEEDINGS OF THE AMERICAN ACADEMY. 



III. 



CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF 

 HARVARD COLLEGE. 



ON THE CUPRIAMMONIUM DOUBLE SALTS. 



THIRD PAPER. 



By Theodork William Richards axd George Oenslager. 



Presented June 9, 1894. 



The work already done upon the double salts of cupriammonium * 

 suggested the possibility of obtaining compounds of fluorine and iodine 

 similar to those of chlorine and bromine. 



Many attempts were made to prepare cupriammonium acetofluoride, 

 Cu(NH3)2FC2H302, with invariable failure. The methods and the pro- 

 portions of the reagents were varied in every possible way ; but 

 nothing could be obtained beside cupriammonium acetate and ammo- 

 nium fluoride. Cupriammonium fluoride itself is very difficult to pre- 

 pare, because of its solubility ; and it is not unnatural that the double 

 salt should be more so. It will be remembered, moreover, that while 

 cupriammonium acetobromide is very easy to obtain, the normal 

 chloride is almost if not quite impossible by the wet way. We should 

 expect the fluorine compound to be even less possible. Because of 

 these continued failures, the work with fluorine was discontinued. 



The investigation of the compounds of iodine proved much more 

 fruitful, yielding the following new substances : — 



(1.) Cu(NH3)3lC2Hs02. 



(2.) 7 CU(NH3)2(C2H302)2.CU(NH3)2IC2H302. 



(3.) 3 Cu(NH3)2 . M NH3. 



(4.) 2 Cu(C2H30o)2NH4CoH302 . HjO, besides confirming the work 

 of Foerster t on the following substances : — 



(0) Cu(NH3)o(C2H302)3. 



(6) CU(NH3)2(C2H302)2 2JH20. 



* Richards and Shaw, These Proceedings, XXVIII. 247 ; Richards and 

 Whitridge, These Proceedings, XXX. 458. 



t Berichte der deutsch. chem. Gesellsch., XXV. 3416. 



