134 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



the instability of cupric sulphocyanate,* might set free or decompose 

 some sulphocyanic acid. Although, as has been said, the analyses 

 are not exact, they are quite sufficiently accurate to prove the for- 

 mula Cu.2(NH3).,(SCN).2, for the respective atomic ratios found are 

 1.01 : 1.00 : 1.00, instead of the theoretical 1:1:1. 



In the analysis the sulphocyanic acid was determined volumetrically 

 according to the method of Volhard, after dissolving the substance in 

 ammouic hydrate and allowing the copper to oxidize by exposure to 

 the air. 



Analyses of Cu.,(NH3)2(SCN)2. 



I. 0.2504 gram of substance gave, on electrolysis, 0.1133 gram of 



copper. 

 II. 0.2297 gram of substance required 16.09 cubic centimeters of a 

 decinorraal solution of silver nitrate for precipitation ofthe sul- 

 phocyanic acid. 

 III. 0.2645 gram of substance required 18.60 cubic centimeters of a deci- 

 normal solution of argentic nitrate for precipitation ofthe sulpho- 

 cyanic acid. 

 IV. 0.2390 gram of substance required, after distilling with caustic 

 potash, 16.57 cubic centimeters of a decinormal acid solution for 

 neutralization. 

 V. 0.2822 gram of substance, after distilling with caustic potash, re- 

 quired 19.84 cubic centimeters of a decinormal acid solution for 

 neutralization. 



Atomic ratios of copper to ammonia and to sulphocyanic acid found 

 1.01 : 1.00 : 1.00. 



* Graham Otto, Michaelis, III. 892. 



