1/2 ANALYSIS OF SOME STEATITES.' 



left a white powder, which when calcined in a red heat 



weighed 62 parts. It was pure si lex. 



precipitated ^^ Ammonia, :rixed with the liquor separated froiTi the 



witti ammonia, ., i „ , • • - • ,. • 



silex, formed m it a yellow precipitate or little bulk, from 



which a part and half of alumine were separated by means 

 of caustic potash. The remainder was oxide of iron, weigh- 

 ing three parts and half. 



and boiled with Q^ After having precipitated the iron and alumine bv 



carbonate of • t • i • 



sodi. . means or ammonia, 1 put mto the liquor a solution of car- 



bonate of soda, and set it to boil. As soon as the mixture 

 began to grow hot, it grew turbid and deposited a large 

 quantity of a white powder, which when washed and cal- 

 cined weighed 27 parts. This substance was magnesia, for 

 with sulphuric acid it formed a salt, that had all the charac- 

 teristics of common sulphate of magnesia. 



Flexible laminar talc therefore is compounded of 



KesuUs of the Silex 62 



analysis. t,^ 



Magnesia • 27 



Oxide of iron 3'5 



Alumine 1 '5 



Water 6 



100 

 Considering the smallness of the quantity of the iron and 

 alumine, I think these substances may be presumed not to 

 be essential to the formation of the stone ; so that perfectly 

 pure laminar talc may be deemed a compound of silex and 

 magnesia, 



Anahjsis of compact rose-coloured talc. 



Compact rose- In the analysis of this variety 1 pursued the same pror 



coloured talc, cesses as in that of the pi-eceding; I therefore need not 



enter into the particulars, but the following are its results. 



Results of its Si^ex G4 



a^^'y-'^i'- Magnesia 22 



Alumine • • 3 



Iron mixed with magnesia* 5 



Water 6 



100 



Analysis 



