Chemical Examination of Thomsonite. 81 



1 atom silicate of lime, _ _ _ _ 5.5 



3 atoms silicate of alumina, _ _ _ 12'75 



2i atoms water, 2-8125 



21-0625 

 But I inadvertently gave Kilpatrick as the locality of the 

 specimen which I employed. It was in reality from Loch- 

 winnoch, a few miles west from Paisley. In tiie 7th volume 

 of the Edinburgh Philosophical Journal, an analysis of Thom- 

 sonite from Kilpatrick, by Berzelius, is given as follows. 

 Silica, .----_- 38-30 



Alumina, - - - - - - - 30.20 



Lime, -___-__ 13-54 



Soda, 4-53 



Magnesia, - . - - - - - - 0-40 



Water, -._---_ 13. jo 



100-07 

 I was rather surprised at this analysis, because I had search- 

 ed for soda in my specimen without finding any. A repeti- 

 tion of the analysis, after reading Berzelius's paper, was 

 attended with no better success. This induced me to make 

 some inquiry of Dr. William Couper, from whom I received 

 the specimen, respecting its true locality. He assured me 

 that it had come from Lochwinnoch, and not from Kilpatrick. 

 This induced me to examine a specimen which I had myself 

 procured at Kilpatrick, and concerning the locality of which, 

 therefore, there could be no doubt. The result of this new 

 analysis was as follows, 



Silica, - - _ _ _ 



Alumina, - - - _ _ 



Lime, _ _ 



Soda, - - _ _ _ 



Water, - - - _ _ 



Vol. IIL 11 



97-55 



