the Zeolite Family. S65 



cimen submitted to analysis, it is quite clear that Berzelius had 

 not distinguished between the Levyine and some chabasite con- 

 tained in the same specimen ; and that in reality the substance 

 analysed consisted of a mixture of both minerals ; so that this 

 analysis may be laid aside. 



From the view adopted by Berzelius that in chabasite the lime, 

 potassa and soda may replace one another in variable propor- 

 tions; and from the circumstance that the mineral found by Ardf- 

 wedson to contain no lime, was from Scotland, I was anxious to 

 know what might be the constitution of a chabasite from Ren- 

 frewshire which I had obtained, and therefore submitted it to 

 analysis. 



The chabasite analysed was in crystals, from the size of one- 

 fifth of an inch to one-tenth, which had the usual rhomboidal 

 form, a very few being slightly modified by truncations on some 

 of the edges and angles. The greater number were transparent 

 and colourless, although a few had a brownish tint. They were 

 in one of the specimens associated with crystals of stilbite, from 

 which, however, they were very carefully separated. 



The method of analysis followed, was that usually adopted in 

 regard to those zeolites which are completely decomposed by 

 acids. The general nature of the constituents having been ex- 

 amined in a previous trial, the mineral reduced to impalpable 

 powder was treated with muriatic acid, and the gelatinous sub- 

 stance evaporated to dryness. The soluble salts were then ta- 

 ken up by hot water, acidulated with muriatic acid ; and the si- 

 lica was separated by filtration, ignited and weighed. The so- 

 lution was next precipitated by ammonia, and the alumina sepa- 

 rated, ignited and weighed. The lime was then thrown down 

 by oxalate of ammonia ; the oxalate of lime was moderately cal- 

 cined ; and the quantity of lime determined from the composi- 

 tion of the earbonate thus obtained. The solution, after the se- 

 paration of the earthy ingredients, was evaporated to dryness, 

 the residue ignited to expel the salt of ammonia, and its weight 

 then determined. This residue was redissolved in water, and 

 left a little silica undissolved, which was collected and weighed ; 

 and its weight then subtracted from that of the whole residue. 

 In the preliminary trial, the mineral had been found to contain 



