384 Foreign Literature and Science. 



20. Analysis of Tourmaline. — Until 1318, chemists had 

 made fruitless endeavors to explain the character which dis- 

 tinguishes the tourmaline from other minerals. Breithaupt 

 sought to prove from theoretical considerations, that bora- 

 cic acid was a principal constituent. In his opinion, boracite, 

 tourmaline, anatase and axinite belong to one family, which 

 he called the schorl family, although these minerals have not 

 the same crystalline system. The first actual discovery of 

 boracic acid in tourmaline, was by an apothecary of Briinn, 

 whose name is Petke. 



The following is the method of analysis adopted by C. G. 

 Gmelin. 



The mineral, reduced to fine powder, was mixed with car- 

 bonate of barytes and strongly heated. The mass was then 

 dissolved in a sufficient quantity of muriatic acid, and the so- 

 lution was evaporated to dryness on a sand bath. M. Gme- 

 lin assured himself, by direct experiment, that at this tem- 

 perature, the quantity of boracic acid which is volatilized is so 

 small, that it may be safely neglected. The silica was ob- 

 tained in the usual way, in treating the residuum of the 

 evaporation with water. Carbonate of ammonia was ad- 

 ded to the fluid, which was then filtered, evaporated to 

 dryness, and heated gradually to a feeble redness. In this 

 way, the boracic acid was retained in combination with the 

 ammonia, and no aqueous acid vapour could be disenga- 

 ged during the calcination, as in the decomposition of sul- 

 phate of ammonia. The residue, after being weighed, was 

 sprinkled with alcohol mixed with a little muriatic acid, and 

 the alcohol, being separated, was set on fire. The same op- 

 eration was repeated, until no trace whatever of green could 

 be perceived in the flame. 



All the boracic acid which had combined with the ammo- 

 nia, and which had afterwards been separated from it by the 

 heat, was thus obtained. The residue again heated and 

 weighed, shewed by its loss, the quantity of boracic acid. 



The quantity of boracic acid which M. Gmelin found in 

 tourmaline of different kinds varied, from nearly two to more 

 than five per cent. Some tourmalines contain lithia to the 

 amount of 2.04 per cent. Soda and potash, or at least one of 

 them are also constituents.- An. de Ch. andde Ph. Nov. 1827. 



21. Capillary Action. — It has been found by M. Emmet, 

 that in a glass tube, in which water rose to 4.575 inches, a 



