370 



*ulphur and 

 carbon. 



Alumine. 



Sulphur. 



Carbon. 



1000 p. ore 

 might produce 

 216 alum. 



Less obtained 

 from defects m 

 tltC process. 



Component 

 parts of the 

 aluminoui 

 schist. 



ANALYpIS OF ALUM OUES. 



culty in it, arising chiefly from the intimate union betv^een 

 the carbon and the sulphur; as these two substances can- 

 not be separated in the dry way, without new gaseous com- 

 pounds being formed. 



The essential parts of the mineral, as an alum ore, are 

 alumine and sulphur. The ordinary processes of analysis 

 give us directly 160 parts as the quantity of alumine in 1000 

 of the ore. The sulphur not being obtainable in a separate 

 state, we must deduce its quantity from that of sulphate of 

 barytes obtained in treating the ore by nitric acid. Accor- 

 ding to what has been said (in C), 1000 parts of the ore 

 produced 270 of this sulphate. From this quantity 46 

 parts are to be subtracted, which were furnished by the vi- 

 triol and gypsum, aud 20 by the sulphate of potash, ad- 

 mitting 15 of this sulphate in 1000 of the ore. Thus there 

 remain but 204 parts of sulphate of barytes produced by 

 this sulphur: but 204 parts of this salt contain 90-75 of 

 sulphuric acid of the specific gravity of 1'85, or 67*5 of 

 concrete acid, which are produced by the oxigenation of 

 28-5 of sulphur. And if (according to E b) the sum of 

 the sulphur and carbon may be taken at 22^5, on deducting 

 28-5 for the sulphur we shall have 196-5 for the quantity of 

 carbon. 



H. Admitting that 1000 parts of crystallized alum, de- 

 composed by muriate of barytes, produce at a mean 945 of 

 sulphate of barytes, we shall find, that the 28-5 of sulphur 

 contained in 1000 of ore may afford 216 parts of albm, 

 provided the proper quantity of potash be added. The 

 component parts of the ore, that produce them^ are not a 

 fifth part of the mass. 



If the quantity of alum obtained, or even that might be 

 obtained in the manufactories, be much less than I have 

 mentioned, this arises from the imperfection of the process 

 emplo^^ed to produce the efflorescence of the ore during its 

 exposure to the air. The oxigenation of the sulphur, and 

 consequent formation of sulphate of alumine, takes place 

 only on the surface of the lumps, and of course the greater 

 part of the ore remains undecomposed. 



I. From the preceding experiments we may infer, thai 

 1000 parts of the earthy alumiapvs 'schist of cFreienwald 



con tain 



Sttlphtttf 



