YO»KSHIRE ALUM WOIIKS. Q^J 



the idea, that this is a volcanic country, where the deoree 

 t*r heat has not been sufficient to put the rocks into a more 

 rapid state of combustiou ; or for want of the access of 

 the sea into the interior part-; of the Eaith. Who can de- 

 termiie, that nature has not yet remaining rocks, which may 

 become vr.lcaaoes in some future ages, when tlie sea has 

 found a j . :^:ciei)i inlet into ihe bowels of the Earth. 



The ob&ej vations I have made with regard to the chemi- 

 cal nature of tht^ schistus are merely indicative of the sub- 

 stances conluiced m it. Indeed experiments would only 

 exhibit a conjectural, and not a real analysis of the schistus, 

 unless a onsideraole number of them were made at differ- 

 ent de ihs, and in various situations of the stratum. 



The colour of the aluminous schistus is a bluish gfray. 

 Its ha) dness differs ; at the top part of the strata it maj' be Characters of 

 crumbled in pieces between the fingers, at a considerable i^he aluminous 

 depth it becomes as hard as roof slate. The specific gravity 

 is about 2-48. 



Alcoiioi digested upon it, and afterward evaporated, 

 leaves a residuum having all tlie properties of petroleum. 



Olive oil, digested upon the schistus, acquired a dark 

 brown colour, most probably from bitumen. 



Exposed to a red heat for a considerable time it loses 15 

 per cent, and assumes a whitish colour, if taken from the top 

 of the rock, and a dull red colour, if taken at about the 

 depth of 40 yards. 



Dilute sulphuric acid wa« poured upon a portion of the 

 schistus; and upon adding prussiate of potash, an abundant, 

 precipitate of prussiate of iron was thrown down from this 

 solution. 



Ammonia precipitates a very considerable proportion of 

 alumine, amounting to 30 per cent^ in some instances. 



Oxalic acid discovers the presence of lime and magnesia. 



Fused with an alkali, muriatic acid precipitates a large 

 proportion of eilex. 



Hence the aluminous schistus contains silex, alumine, 

 magnesia, lime, oxide of iron, bitumen, sulphur, and water. 



Of the Calcination and Lixiviation of the Schistus, 



The covering strata are removed previous to working Method of 



the wor.'^ifS ^^ 



