344 Dr. Ginelin's Analysis of Pefalite, [May, 



Silica, i 73-37 



e 0-80 



74-17 74-17 



Alumina, r 17-41 



Lime, d 0-32 



Moisture, a 2-17 



94-07 

 (B.) ... 



To determine the portion of lithia contained in petalite, 100 

 parts (4 grammes) of the mineral in fine powder were mixed with 

 800 parts of carbonate of barytes, and exposed for two hours to 

 a white heat in a platinum crucible. The mass did not dissolve 

 completely in muriatic acid, but it was obvious from the appear- 

 ance of the residual matter, that it had been completely acted on 

 by the barytes. The solution was evaporated to dryness, and 

 the silica separated. It weighed 77-5 parts. 



Thus in the present experiment, the quantity of silica some- 

 what exceeds that found in the preceding one. 



After the separation of the silica, the liquid was mixed with a 

 greater proportion of sulphuric acid than was requisite to throw 

 down the barytes : after which the alumina and lime were thrown 

 down bv dijjestion with carbonate of ammonia. 



The filtered solution was, in the first place, reduced to a small 

 quantity by evaporation in a platinum cup. It was then evapo- 

 rated to dryness, and heated to redness in a large platinum 

 crucible to get rid of the muriate and sulphate of ammonia. 

 There remained 16-2 parts of fused sulphate of lithia ; equivalent 

 to 5-16 parts of lithia. 



Hence the constituents of petalite are as follows : 



Silica 74-17 



Alumina 1 7-41 



Lithia 5-16 



* Lime 0-32 



Moisture 217 



99-23 

 Loss 0-77 



100-00 



This analysis differs considerably from that made by Messrs. 

 Clarke and Holme, Besides their not having found any indica- 

 tion of the presence of an alkali, the quantity of oxide of manga- 

 nese which they detected is by far too great. In perfectly pure 

 specimens of petalite, which I selected ibr my analysis, I could 

 detect no manganese whatever ; though its presence was obvious 



