On definite Proportions. 203 



calculation differs^very little from the analysis: 100 parts 

 of the acid ought to combine with 101'45 of the oxide ; 

 and the difference may perhaps depend on a portion of 

 water left behind in the salt. It appears also that in this 

 sulphate 100 parts of melallic copper are united to 50 of 

 sulphur, which is very little less than twice the least quan- 

 tity that copper takt'S up in the form of a sulphurel. 



I imagined also that the subsulphate of copper, already 

 known, must contain copper and sulphur in the proportion 

 determined by this experiment. I precipitated, in order to 

 examine this, a ^oluiion of the sulphate of copper by means 

 of caustic ammonia, so that the whole of the copper was 

 not thrown down. The subsalt was washed and dried oil 

 a filler, and gently ignited. When dissolved in nitric acid, 

 and precipitated by nitrate of baryta, it appeared to consist 

 (7f 20 parts o!" sulphuric acid, and 80 parts of oxide of cop- 

 per. Consequently the acid was combined, in this subsalt, 

 with nearly four times as much of the base as in the neutral 

 salt, and 100 parts of copper take up, in this case, only 

 half as much sulphur as in the suljihuret of copper. Hence 

 it seems probable that copper and sulphur must exist in the 

 required proportion in the sulphate of the protoxide of 

 copper: of this salt, however, I am unacquainted with 

 the characters and with the mode of preparation ; its com- 

 })osition may however be calculated in two ways, which 

 afford nearly the same result. In the sulphuret of copper, 

 if 100 parts of copper take up 25 of sulphur, 1'25 parts of 

 this substance must give 173*86 of sulphate of the prot- 

 oxide, and 100 parts of sulphuric acid will be combined 

 with 183 of the protoxide. We shall find hereafter that 

 100 parts of the muriatic acid are saturated by 278-4 of the 

 protoxide of copper ; and since they are also saturated by 

 C8S'4of tsaryta; and since lOOof sulphuric acid combine with 

 194 of baryta, we have 187 for the prtiportion of protoxide 

 of copper answering to 100 of sulphuric acid ; for, 288*4 : 

 278*4=194:187; and this number differs but little from 

 183, the result of the former calculation. 



VIII. .Muriate OF Copper. 

 T have advanced the conjecture, that every other acid, as 

 well as the suljihuric, in order to be saturated by a base, 

 rtrfliires the same (piantity of oxygen to be contained in it: 

 and in order to examine the truth of this opinion, I fixed 

 on the muriatic acid. 



A, Muriate of the Protoxide of Copper. 

 A solution of this substance in cooccntratcd moriatic 



acid 



