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Intelligence and Miscellaneous Articles, 



results, — by teaching him to conjure up inflammatory spirits from 

 the surface of the "vasty deep," and to turn water into fire, — Sir H. 

 Davy has shown it is not necessary that Pluto should ascend from 

 the lowest depths of his empire to produce the phenomena of vol- 

 canos, and much less so to bring about a chemical union between 

 silex, alumina, lime, and iron, the chief constituents of basalt or 

 trap. Nee Deus intersit dignus nisi vindice nodus. 



ANALYSES OF TOURMALINES. 



M. Gmelin has analysed a great many varieties of this mineral • the 

 method adopted is the following : — The mineral reduced to a fine 

 powder is mixed with carbonate of barytes, and strongly heated. The 

 mass is afterwards treated with a sufficient quantity of muriatic acid 

 to dissolve it entirely, and the solution is evaporated upon a sand 

 bath to dryness. M. Gmelin ascertained by direct experiment that at 

 this temperature the quantity of boracic acid volatilized is so minute 

 that it may be neglected without any sensible error. The silica is ob- 

 tained in the usual manner, by treating the residuum of evaporation 

 with water. Carbonate of ammonia is added to the solution, and 

 after filtration, and evaporation to dryness, the residuum is gradually 

 heated to low redness. In this manner, no boracic acid can be lost, 

 because it is combined with ammonia • and thus during calcination at 

 a red heat, no acid or aqueous vapour is evolved, as in the decompo- 

 sition of sulphate of ammonia. The residuum after being weighed, is 

 washed with alcohol mixed with a little muriatic acid j the alcohol 

 being separated is burnt • the operation is repeated until the alcohol 

 does not give a green flame. All the boracic which is combined with 

 the ammonia is thus obtained. The residuum again heated and dried, 

 and the loss of weight determines the quantity of boracic acid. 



Tourmalines are divided by M. Gmelin into three classes : the first 

 of which contains lithia : — I. Red Tourmaline from Rdsna in Moravia ; 

 sp.gr. 2*96 to 3*02. II. Red Tourmaline from Perm in Siberia; sp. 

 gr.3'059. III. Celadon Green Tourmaline from Brazil ; sp. gr. 3*079. 



Tourmalines 



