188 Foreign Literature and Science. 



7th. The influence of atmospheric air, which thus mani- 

 fests itself, by the disengagement of azote, and the destruc- 

 tion of the sulphurous compound, is reproduced upon acid- 

 ulous waters with the disengagement of azote, and accord- 

 ing to all appearances, with the formation of carbonic acid. 



28. Incombustible cloth. — Gay Lussac has ascertained that 

 the hydrocholate (muriate) sulphate, phosphate, and bo- 

 rate of ammonia, borax, and some mixtures of these salts, 

 are the most proper substances for rendering linen, or cot- 

 ton cloth incombustible without changing their qualities. 



29. Cobalt. — Dobcreiner has contrived the following 

 method to separate cobalt from nickel, and other metals 

 from their oxids. 



The oxide of cobalt or of nickel is mixed with oxalic acid, 

 and exposed in a retort to the heat of a spirit lamp. When 

 no more vapours are disengaged, or when the metal has ac- 

 quired an ash-grey colour, the heat is withdrawn, and there 

 is found in the bottom of the retort a pulverulent precipi- 

 tate, which is the pure metal. This precipitate is intro- 

 duced into a glass tube, and when subjected to a slight fu- 

 sion, a button of pure metal is speedily formed. 



Bui. de la Soc. D'' Encouragement. 



30. Pyrolignous acid. — There can be little doubt that the 

 ordinary practice of curing meat by smoking, depends upon 

 the action of pyrolignous acid, disengaged by (he slow, and 

 imperfect coml)ustion of the fuel. It has accordingly been 

 found that meat may be preserved, after it has been salted, 

 by dipping it into an aqueous infusion of the soot of wood. 

 A pound of soot is sufficient to cure three pounds of beef. 

 The soot is put into a vessel with four pints of water, and 

 allowed to macerate during 24 hours, with frequent stirring. 

 It is then decanted, and it is found to be charged with about 

 -^^ of its weight of the acid, and bituminous principles 

 of the soot. In this solution the meat remains half an hour. 

 It is then taken out and dried in the open air, and may be 

 preserved at pleasure. 



Bui. D'Encour. Jngust 1821. 



