CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF 



HARVARD COLLEGE. 



ON THE CUPROSAMMONIUM BROMIDES AND THE 

 CUPRAMMONIUM SULPHOCYANATES. 



By Theodore William Richards and Benjamin Shores JMerigold. 



Presented November 10, 1897. 



With regard to the possible compounds of cuprosammonium our 

 knowledge is by no means complete. Many compounds which we should 

 expect to find are not mentioned in chemical literature, and many which 

 have been found are very imperfectly described. The present paper 

 records the results of an investigation which had as its aim the filling 

 up of some of the gaps in this direction ; in particular we hoped to dis- 

 cover cuprosammon'mm double salts of the type Cu2(NH3)2BrC.2H302, 

 analogous to the cw/>n'ammonium compounds which have recently been 

 investigated here. While this latter hope has not yet found its fulfil- 

 ment in fact, we have succeeded in preparing four new simple cuproS' 

 ammonium compounds : — 



(1) Cu2(NH3)oBr„, 



(2) Cu2(NH3)2(SCN)2, 



(3) Cu2(NH3)„Br2, 



(4) Cu2(NH3),(,)(SCN)2; 



and one cwjonammonium sulphocyanate : — 



(5) Cu(NH3)4(SCN)2. 



1. Cuprosammonium Bromide, CuoBr, . 2 NH3. 



To prepare this compound, about ten grams of precipitated cuprous 

 bromide were dissolved in the least possible amount of ammonic hydrate 

 solution, and about twenty-five cubic centimeters of acetic acid were 

 added. All operations were carried on with the help of a complex ap- 

 paratus in an atmosphere of hydrogen, and the solution was evaporated 

 spontaneously over sulphuric acid in a bell jar filled with hydrogen. 

 After a day or two the bromide crystallized out in long colorless crystals. 



