Clarice and Steiger — Action of Ammonium Chloride. 27 



Akt. III. — The Action of Ammonium Chloride upon cer- 

 tain Silicates ; by F. W. Claeke and Geoege Steigee. 



In our previous communications* upon the ammonium 

 chloride reaction, we have shown that different silicates are 

 very differently affected by the reagent. From analcite, leu- 

 cite, natrolite and scolecite we obtained new salts, in which 

 the alkali or lime of the original mineral had been replaced by 

 ammonium. On the other hand, prehnite was practically 

 unattacked, while the pectolite molecule was quite thoroughly 

 broken down, with liberation of much free silica. We now 

 submit the results obtained with several additional silicates ; 

 results which serve to emphasize our former conclusions. 



Our mode of operation has been precisely the same as 

 before. Each mineral, in tine powder, was intimately mixed 

 w T ith four times its weight of dry ammonium chloride, and 

 the mixture was then heated for about five or six hours to 

 350° in a sealed combustion tube. After cooling, the mixture 

 was leached out with water, and the air-dried insoluble residue 

 was analyzed. Determinations of free silica were effected by 

 boiling the mineral, or its derivative, for fifteen minutes with 

 a solution of sodium carbonate containing 250 grams to the 

 liter. From the solution so obtained the silica was recovered 

 by acidulation with hydrochloric acid and evaporation to dry- 

 ness. In each case all of the experiments were made upon 

 one uniform sample of material, so that the data for any one 

 species are strictly comparable. So much premised, we may 

 go on to consider the results of our investigations. 



Stilbite. 



The specimen selected for study was a nearly white, typical 

 example from Wasson's Bluff, Nova Scotia. The analysis and 

 the fractional water determinations were as follows : 



SiO .... 



Analysis. 

 55-41 



Fractional water, 

 At 100° 



3-60 



A1.0, ... 



Fe 2 3 ... 

 MgO ... 

 CaO .... 

 Na 2 0.... 

 HO 



16-85 



-18 



-05 



7-78 



1-23 



19-01 



" 180° 



" 250° 



" 350° 



6-46 

 3-80 

 2-10 



Low redness 



Full " 



Over blast 



2-95 

 •06 

 •04 



2 







100-51 19-01 



This Journal (4), ix, pp. 117, 345 ; February and May, 1900. 



