30 Clarke and Steiger — Action of Ammonium Chloride. 



Heulandite. 



Pure, white heulandite from Berufiord, Iceland, was the 

 material taken for investigation. Upon boiling with sodium 

 carbonate, 1'73 per cent of silica went into solution. From 

 previously ignited heulandite only 1-14 percent was extracted. 

 No silica, therefore, was liberated upon ignition, and a hydrous 

 metasilicate formula for the mineral seems to be improbable. 

 Only one lot of the ammonium chloride derivative was pre- 

 pared, and its composition, together with that of the heulandite,. 

 is given below. 



Heulandite. Ammonium salt. 



Si0 2 -57-10 01-24 



A1,0 3 16-82 18-00 



Mo-0 -07 



CaO 6-95 2-56 



SrO ------- '46 



Na 2 0__.-._ --..-...- 1-25 ) 



K 2 -42 \ 



NH 3 ---- 4-42 



H 9 Oatl00° 3-61 ) 



H 2 above 100° .13-00 f L6 bd 



99-68 100-45 



Here again we have the same kind of transformation as 

 before, but rather less complete than in the case of stilbite. 

 That the ammonium taken up is equivalent to the bases 

 removed, is shown by a study of the ratios. Ignoring water 

 and the soluble silica, the heulandite ratios are as follows : 



or, uniting bases, 



R" 1 «Al, 10 (Si t O,)„.(SiO 4 ) lt . 



Again simplifying, this becomes 



R" 15 4 A1 330 X 3 2 4> 



or very nearly 1 : 2 : 2, as in stilbite. 



Similarly discussed, the ammonium salt gives the ratios 



R' 270 Ca 46 Al g52 Si l02i O 27463 

 equivalent to 



R' M .Al lii X 1H ,or 1:1:1. 



In both cases the orthosilicate molecules are few, and the com- 

 pounds approximate to trisilicates very closely. 



Chabazite. 



Characteristic flesh-colored crystals from Wasson's Bluff, 

 Nova Scotia, The analysis and fractional water determina- 

 tions are as follows : 



