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their full portion of water of cryflallization ? Tlie author 

 refers us to the 71ft volume of the Philofophical Tranfadlions 

 for an account of Dr. Black's paper. However, in thofe of 

 the Royal Society of London (the only known by that title 

 without addition) no fuch paper is to be found. If the alkali 

 were fufed, the bodies in its neighbourhood were fufed alfo ; 

 without fome knowledge of their ftate nothing more can be 

 faid ; the cafe is not fairly before us. I make no doubt, however, 

 but Dr. Black has examined all circumflances with that ikill 

 and accuracy which he is known to poflefs. 



I DECLINE mentioning a few other difFufc objedllons to the 

 aqueous theory, which appear to me to fhew nothing more than 

 the difficulty of accurately explaining various circumftaaces of 

 the mineral kingdom. The only point to be confidered is 

 which of the two fyftems, the aqueous or the Igneous, Is, upon 

 the whole, leaf): exceptionable, and on this head enough has 

 been already faid. I cannot however omit noticing, for the 

 fake of the difcufllon It leads me to, that the application of our 

 author's fyflem to the formation of granite Is peculiarly unhappy. 

 This rock is formed of ftones of different degrees of fufibllity, 

 which, in a heat capable of melting quartz, fhould naturally 

 run Into each other ; It moft frequently contains mica, which, 

 when melted, affumes an appearance very different from the 

 plated flrudlure It naturally prefents ; and, to crown all, can be 

 formed In the moift way, but cannot In the dry : Here I have 

 the misfortune of differing with another zealous patron of the 

 Igneous Theory, equally fkilled in mineralogy and chymiftry, 



the 



