230 Proceedings of Philosophical Societies. [Sept. 



be obtained from tbese wines by means of potash, though by that 

 means we may separate the smallest quantity of alcohol added on 

 purpose to wine. 



M. Gay-Lussac has endeavoured to restore the old opinion, by 

 showing that potash shows likewise the quantity of alcohol natural 

 to wine when the liquid has in the first place by means of litharge 

 been freed from the substances which prevented its separation: and 

 that alcohol may be obtained by distilling wine at the temperature 

 of 6"0°, which is considerably below the heat produced by fermen- 

 tation. 



But it may be alleged that M. Gay-Lussac operated upon wines 

 in which alcohol had been already formed by fermentation, or upon 

 wines into which the merchants had introduced alcohol. To 

 obviate this objection he made himself wine from grapes, and found 

 alcohol in it, as well as in every other wine.* 



M. Gay-Lussac has also shown that the absolute alcohol of 

 Richter may be obtained by employing quick lime or barytes instead 

 of muriate of lime. 



Soap, as every body knows, is a combination of an alkali and a 

 fatty matter ; but the alteration which the oil experiences by this 

 combination had not been sufficiently examined. 



M. Chevreul, Assistant Naturalist to the Museum of Natural 

 History, has employed himself in this inquiry, and has made some 

 new and curious observations. The soap of potash and hog's-lard 

 dissolved in water leaves a pearl coloured substance, which, when 

 separated from the saline matter which it still contains, constitutes 

 a substance possessed of very peculiar properties, which M. 

 Chevreul calls margarine, from its pearl colour. It is insoluble in 

 water, but very soluble in hot water. It melts at 133°, and on 

 cooling crystallizes in beautiful white needles. It combines with 

 potash, and then resumes the characters of the pearl-coloured 

 deposite. It has a stronger affinity for that base than carbonic acid 

 has, which it expels from the carbonate of potash by the assistance 

 of a boiling heat. It likewise separates potash from turnsole, and 

 restores it to its red colour. 



* It is singular (hat no noiice is taken here of the experimenti of Mr. Brande, 

 published some years ago in the Philosophi al Transactions. It would be dis- 

 graceful to suppose that none of the Members of the Institute had seen that 

 volume. — T. 



(To be continued.) 



