342 Scyberfs Analysis of the Maclureite. 



in his analysis of the Pyrophysahte, Pycnite and other 

 Topazes. 



Analysis. 



A. Three grammes of the pure mineral, finely pulver- 

 ized and subjected to the action of a red heat, underwent 

 no material alteration, except a diminution of 0.03 gr. on 

 3 grammes, hence we have LO per. 100 of water. 



B. The calcined mineral (A), was exposed to a red heat, 

 during one hour in a platina crucible, with 18 grammes of 

 crystallized sub-carbonate of soda, the mixture did not 

 fuse, when cold its colour was yellowish brown, it was 

 treated with water and the solution was filtered, the filtered 

 liquor was treated with an excess of acetic acid, when 

 treated with carbonate of ammonia it gave no precipitate; 

 it therefore contained no silica: it was again supersaturated 

 with acetic acid and boiled to expel the carbonic acid, the 

 excess of acetic acid was then neutralized with ammonia, 

 and the liquor was treated with muriate of Lime, which 

 occasioned a white, flaky precipitate, possessing the proper- 

 ties of fluate of lime ; when calcined, it weighed 0.44 

 ijrammes: this result was verified by a second experiment, 

 in which I obtained 0.43 grammes of fluate of lime, and 

 on calcining the mineral a second time, with sub-carbonate 

 of soda, I ascertained that the fluoric acid had been com- 

 pletely separated, the 0.44 grammes of fluate of lime are 

 equivalent to 0.12258 grammes of fluoric acid on 3 gram- 

 mes, or 4.086 per 100. 



C. The residue, on the filter (B), was treated with mu- 

 riatic acid, which converted it into a jelly; it was evaporated 

 to dryness, then treated with wafer acidulated with muriatic 

 acid, and again moderately evaporated, more water was 

 added and the solution was filtered, the silica, remaining 

 on the filter, after edulcoration and calcination, weighed 

 0.98 grammes on 3 grammes, or 32.G66 per 100. A sec- 

 ond expLriment yielded precisely the same quantity of 

 silica. 



D. The iron was separated from the liquor (C), as ia 

 the 1st Analysis; the per-oxide thus obtained, weighed 

 0.07 grammes on 3 gr. or 2.333 per 100. 



