342 Dr. Gmelm'sAmh/sis of Petalite, [May, 



the case when minerals are decomposed by means of barytes, 

 the silica was not entirely dissolved, a considerable portion of 

 it appearing under the form of light transparent white flocks. 

 The solution was evaporated to dryness in a platinum capsule, 

 and the silica separated by the filter. After this, a greater por- 

 tion of sulphuric acid was added to the liquid than was necessary 

 to precipitate the whole of the barytes. The sulphate of barytes 

 was separated by the filter, and the liquid was evaporated in a 

 platimim capsule till it was reduced to a small quantity in order 

 to get rid of the greatest part of the excess of muriatic acid 

 which was present. It was then supersaturated with carbonate 

 of ammonia; and after the precipitate, consisting probably of 

 alumina and a little oxide of iron, had been separated by the 

 filter, it was evaporated to dryness in a large platinum crucible, 

 and heated to redness, in order to drive off the muriate and sul- 

 phate of ammonia which it contained. The residual mass was 

 redissolved in water, and the solution mixed with hydrosulphuret 

 of ammonia as long as any black precipitate consisting of 

 sulphuret of manganese contimied to fall. The filtered solution 

 was again evaporated to dryness, and exposed to a red heat. 

 The sulphate thus obtained was dissolved in water, and decom- 

 posed by means of acetate of barytes. The sulphate of barytes 

 was separated by the filter. The liquid was evaporated to dry- 

 ness, and the residual mass heated to redness in a platinum 

 crucible. The matter thus obtained exhibited strongly the 

 properties of an alkali even after it had been well washed with 

 boihng water. The solution of carbonate of lithia in water was 

 evaporated till the greatest part of the salt was deposited in the 

 state of a crystalline powder, over which a very small portion of 

 liquid swam. This crystalline powder was thrown into a funnel 

 to allow the liquid to drop from it, and it was likewise washed 

 with cold water, in order to remove any trace of soda with which 

 it might possibly have been contaminated. I must, however, 

 remark, that in my experiments on petalite, I have never met 

 with any traces of soda. 



A portion of this pure carbonate of lithia was converted into a 

 sulphate by means of sulphuric acid, and rendered neutral by 

 exposure to a strong red heat. It was then dissolved in water 

 and crystallized. 



My analysis of this salt gives its composition as fellows : 



•Sulphuric acid 58-34 68-15 



Lithia 27-25 31-85 



Water 14-41 



100-00 100-00 



Its comes very nearly to the numbers given by Vauquelin in 

 his analysis (Ann. de Chim. et de Phys. vii. 287). The compo- 

 sition of the salt; as given by that chemist, ie as follows : 



