302 



CHEMICAL ANJirSlS of an 



■weighed 17} grains, and was found on examination, to be pure 

 fulphate of foda *. 



By Mr Kirwan's eftimation, 17! parts of dry fulphate of 

 foda contain nearly 8 parts of alkali; confequently, from 100 

 parts of the zeolite there have been obtained by the procefs laft 

 defcribed, 8 parts of foda. This refult correfponds with the 

 former, in which the alkali was colleded in the ftate of muriate 

 of foda, as nearly as can be expedled in fuch experiments ; and 

 it muft be remembered, that the proportions of the compofteiit 

 parts of neutral falts are not afcertained with precilion. [•,"•,' 



According to tlie different experiments now detailed, 100 

 parts of this zeolite contain, 



Silex(No.i.) - - 51-5 



Lime (No. 3. and 4.) - 32 



Argil (No. 2.) - • •$ 



Oxyd of iron (No. 2.) - - -5 



Soda, about - - - 8.5 



Carbonic acid and other volatile matter, 5. 



with fome traces of magnefia and muriatic acid. 



The 



» The experiments which fliewed that foda was the alkaline bafis of this fait, 

 have not been ftated here -, becaufe I formerly gave a defcription of the methods 

 ufed in examining the fame fait, in the paper on Whinftone and Lava, pubhfhed 

 in Part I. of this volume, (p. 85.). To avoid unneceffary repetition, I beg leave 

 to refer to that paper, both v^ith regard to the manner m which I endeavoured to 

 determine the purity of the faline matter, and alfo that of the filex, and fon»e 

 other earths. 



