266 CLARKE 



4A],Na3(Si30,),Cl, 

 ioAl,Na3(SiOJ,Cl, 

 25Al3Na3(SiO,)3; 

 which may be compared with the reduced analysis as follows : 



Calculated. Fouud, reduced. 



SiO, 43.53 43-75 



AI2O3 32.02 32.68 



NajO 22.11 21.26 



CI 3.03 2.99 



100.69 100.6S 



Less O 69 .68 



100.00 100.00 



The agreement is as close as we could reasonably expect it 

 to be, when we remember that the substance was formed at a 

 temperature above the melting point of sodium chloride. One 

 of the chlorinated molecules, it may be observed, is curiously 

 like kaolin in structure, as a comparison of the probable for- 

 mulas will show. 



,0— H yCl 



Al— SiO,=H3 Al— SiO.^Naj 



^SiO^sAl ^SiO^^Al 



Kaolin. New compound. 



These expressions have the merit of suggestiveness and may 

 lead to new experiments by and by. The compounds should 

 be derivable the one from the other, if the comparison between 

 them is really sound. 



In addition to the derivatives mentioned in the foregoing pages, 

 Mr. Steiger has prepared ammonium, silver, and thallium 

 natrolite, thallium mesolite, ammonium and silver scolecite, 

 ammonium leucite, ammonium heulandite, etc. These products 

 are sufficiently described in Survey Bulletins 207 and 262. 



