1824.] the Metallic Sulphates by Hydrogen Gas. 337 



carbonate of potash. As soon as inconsequence of the conti- 

 nued application of heat, all excess of carbonic acid was driven 

 off. The precipitate was collected on the filter and washed. 

 After being heated to redness, there remained 0-146 gr. oxide 

 of zinc equivalent to 0*117 gr. of metallic zinc. The remainder 

 of the 0-393 gr. or 0*276, therefore, was sulphur. 



b. The sulphuric acid formed by the first digestion in aqua 

 regia was precipitated by muriate of barytes. There were 

 obtained 2-288 grs. of sulphate of barytes, equivalent to 0-786 

 sulphuric acid, or 0-316 sulphur. 



c. The residual liquid was mixed boiling-hot with carbonate 

 of potash, taking the necessary precautions that none of it was 

 lost in consequence of the effervescence . When no more car 

 bonic acid was disengaged, the carbonate of zinc was collected 

 on the filter and washed. When heated to redness, it left 1-311 

 gr. of zinc oxide, and, except a trace of iron, it did not appear 

 to contain any other substance in solution : 1-311 oxide is equi- 

 valent to 1-05 metallic zinc. Thus it appears that 1*758 blende 

 contain 



Zinc a 0-117 



b 1-050 



1-167 



Sulphur a 0-276 



b 0-316 



0-592 



1-759 

 Or in 100 parts : 



Zinc 66-34 



Sulphur 33-66 



100-00 



This is two atoms of sulphur to one atom of zinc for Zn : 2 S 

 :: 66-34 : 33-09. 



Sulphate of Cobalt. 



1. 0-639 gramme of pure crystallized sulphate of cobalt ; but 

 previously freed from water by heat, were treated in the way 

 already described, with hydrogen gas. At a high temperature 

 the salt was easily and rapidly decomposed ; sulphurous acid and 



piuly ue 

 water were formed ; and a dark grey cohering mass remained, 

 which weighed 0-345 gr. In a subsequent experiment, the 

 weight remaining from 0-772 gr. of the salt, was 0-412 gr. The 

 substance thus obtained dissolved in a great measure in muriatic 

 acid, without the extrication of any gas. When the mass was 

 heated, it was attacked a little more by the acid, and a little 

 sulphuretted hydrogen gas was disengaged. The undissolved 

 Netv Series, VOL. v II. z 



