302 CHEMICAL ANALYSIS of an 



weighed \rjX grains, and was found on examination to be pure 

 fulphate of foda *. 



By MrKiRWAN's eftimation, 1 j± parts of dry fulphate of 

 foda contain nearly 8 parts of alkali ; confequentlv, from 1 oc 

 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 collected in the ftate of muriate 

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

 it muft be remembered, that the proportions of the component 

 parts of neutral fairs are not afcertained with precifion. 



According to the different experiments now detailed, 100 

 parts of this zeolite contain, 



Silex (No. 1.) 



Lime (No. 3. and 4.) 



Argil (No. 2.) 



Oxyd of iron (No. 2.) - - 



Soda, about - 



Carbonic acid and other volatile matter, 



with fome traces of magnefia and muriatic acid. 



98. 



The 



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

 have not been ftated here ; becaufe I formerly gave a defeription of the methods 

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

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

 to refer to that paper, both with regard to the manner in which I endeavoured to 

 determine the purity of the faline matter, and alfo that of the filex, and fome 

 other earths. 



