JFoote and Bradley — Chemical Composition of Analcite. 437 





5. Michigan, U. S. A. 









I 



II 



Average 



Eatio 



SiO, 



... 56-53 



56-43 



56-48 



4-45 



A1 2 3 



... 21*85 



22*42 



22*13 ) 

 •21 f 



1-02 



MgO 



•26 



•16 



K s O 



•09 



•13 



•11) 

 13-04 j 



l'OO 



Na,0._... 



... 12-92 



13-16 



H 8 



8-37 



8-41 



8-39 



2-21 



100-02 100-71 100-36 



6. Montreal, Canada. 



I II Average Eatio 



Si0 2 56-96 56-72 56'84 4'61 



A1 2 3 22*75 22-88 22-81) 



Fe 2 3 _ -25 '19 -22 j" i Uy 



K 2 -16 '21 -19) 



Na 2 12-67 12-72 12-69 J 



H 2 8-23 8-31 8*27 2'25 



101-02 101-03 101-02 



The summary of the ratios obtained in these six new analy- 

 ses is given below. There are included also the ratios from the 

 analyses by Hillebrand (.N"o. 7) and by Clarke and Steiger 

 (No. 8), which appear to be as good as any that have been made. 



Table IV. — Summary of Eatios. 

 No. Si0 2 A1 2 3 , etc. Na 2 0, etc. H 2 0. 



1. 4*46 1-06 1-00 2-24 



2. 4-16 1-07 " 2-12 



3. 4-18 1-05 " 2-17 



4. 4-29 1-05 " 2-19 



5. 4*45 1-02 " 2-21 



6. 4-61 1-09 " 2-25 



7. 4-27 1-01 " 2-15 



8. 4-82 1-07 " 2-53 



The ratios in Table IV confirm the general statement which 

 was made from a consideration of old analyses, that the 

 accepted formula is not in good agreement with the facts of 

 analysis. Silica and water both show ratios which are always 

 higher than the formula requires, and in most cases are very 

 much higher. The ratio Na 2 : A1 2 3 is nearly 1 : 1. The 

 average of all results 1 : 1*05. The ratio H 2 : Si0 2 is very 

 close indeed to 1 : 2. Considering the low molecular weight of 

 water, this ratio is as close as could be expected. The average 

 is 1 : 1*97. To sum up the matter, soda and alumina on the 



Am. Jour. Sci.— Fourth Series, Vol. XXXIII, No. 197.— May, 1912. 

 29 



