402 Rev. Mr. Gregor on the TremoUte of Cornwall, 



the alkali by pure nitric acid, and subjecting the solution to the 

 ordinary tests. 



Fifty grains treated in the usual way, with nitrat of barytes, &c. 

 furnished an alkaline salt, which when united with sulphuric acid, 

 assumed the figure of sulphat of soda by crystallization. But the 

 quantity of this salt was too small to admit of being weighed. 



One hundred grains exposed to a red heat for a quarter of an 

 hour, were diminished in weight one grain. Pure alkalies do not 

 effect the decomposition of this mineral so easily as they do in the 

 state of carbonats. 



One hundred grains were mixed and fused with 400 grains of 

 dried carbonat of soda, in a platina crucible. Treated with mu- 

 riatic acid spongy flocks of siliceous earth subsided. Ammonia 

 precipitated from the decanted fluid a gelatinous matter of a reddish 

 brown, which was suflficiently edulcorated ; and after ignition, was 

 treated with muriatic acid, which left a small portion of silica un- 

 dissolved. Sulphuric acid separated some gypsum. The contents 

 of the solution were now thrown down by means of an alcoholic 

 solution of potash, and the brown precipitated matter was boiled 

 with a superabundant quantity of the precipitant. The clear alka- 

 line fluid was treated with muriat of ammonia, which separated 

 some alumina, but in a quantity too minute for collection. Though 

 this circumstance occurred twice, I am disposed to think that the 

 presence of alumina should be considered as an accidental intrusion. 

 The brown precipitated matter consisted of oxide of iron with a 

 trace of manganese. The first solution from which ammonia could 

 precipitate nothing further, was assayed with carbonat of soda, 

 which separated a white matter, which was increased by boiling the 

 fluid, even to dryness. It consisted of carbonat of lime and mag- 



