Dr. Kane on the Compounds of Ammonia. 33 



When the brown mass resulting from the desiccation of this salt is moistened, 

 it evolves much heat, and combines with a large quantity of water, forming a 

 green mass of a livelier colour than it originally possessed, and becoming always 

 of something more than its former weight. The quantity of water with which 

 it combines varies from 23 to 24 per cent., and hence I attribute the slight defi- 

 ciency in water shown by analysis, to some of the chemically combined water 

 having been expelled by the very moderate heat applied in drying the precipitate 

 for analysis. 



It will be remarked that by 300° F. exactly half of the water is expelled ; 

 hence there must be some difference in the degrees of affinity with which the 

 two quantities are retained. From these considerations I am disposed to give to 

 the formulae for these basic sulphates the following form : 



or 



cuo . SO3 . cwo -\- 6 (cMO -\- 2 ho), 

 cuo . SO3 . CMO -j- 6cuo 4" 6ho -{- 6ho ; 



the second group of equivalents of v/ater being expelled by a temperature lower 

 than that necessary for the separation of the remainder. 



Thompson had long since pointed out the existence of a basic sulphate of 

 copper containing two equivalents of oxide, and this in its hydrated condition he 

 states to retain two equivalents of water. When this is added to those above 

 described, the series of basic salts follow from the neutral sulphate in the follow- 

 ing: order : 



'& 



Real neutral sulphate = cm.o + SO3 



Do. with saline water = cuo . ho -f- SO3 



First basic salt, dry =: cmo . cuo -j- SO3 



Do. do, hydrated = cmo . cuo + SO3 -|- 2 ho. 



VOL. XIX. F 



