CHEMICAL SCIENCE. 241 



established and made clear to the eye is, that the air of our large cities is suf- 

 ficiently impure to account for much of its unhealthiness, and the air of our 

 hills and seas and lakes sufficiently pure to account for its salubrity. 



ARTIFICIAL PRODUCTION OF TARTARIC ACID. 



M. Pelouze recently informed the French Academy that he had, in con- 

 nection with Baron Liebig, by the action of nitric acid on gums, etc., and 

 the sugars analogous to the sugar of milk, etc., succeeded in converting 

 these substances into tartaric acid, quite identical with the tartaric acid of 

 nature. This transformation cannot be doubted, for it has been confirmed 

 by a multitude of chemical and optical experiments; and with the aid of 

 the artificial acid, Liebig has prepared tartrates of soda and potash, and 

 even tartar emetic. The announcement of this great discovery was received 

 with great enthusiasm. It has long been sought for by chemists, who 

 have, however, generally experimented on grape and cane sugar, instead 

 of sugar of milk, gums, etc. 



RELATION BETWEEN FERMENTATION AND CRYSTALLIZATION. 



In 1834 Mr. Schroeder, in connection with Mr. Dusch, published a paper 

 on fermentation and putrefaction, and showed that putrescent and ferment- 

 able substances could be indefinitely preserved, if, instead of leaving such 

 matter in common air, they were placed in vases filled with air that had 

 been filtered through cotton. Flesh, soup, and all kinds of alimentary sub- 

 stances can thus be preserved, if the precaution has been taken previously 

 to boil them in water. 



Mr. Schroeder shows that what he has established concerning fermenta- 

 tion and putrefaction, is also true of crystallization. It is well known that 

 a saturated solution of sulphate of soda remains liquid as long as it is in 

 vacuo, but solidifies on access of air. Mr. Schroeder establishes the fact that 

 crystallization does not take place if the air is made to pass through a tube 

 filled with cotton. 



Mr. S. explained the results of his experiments in 18-)4, by supposing that 

 the air filtered through cotton is deprived of the spores of cryptogamic infu- 

 soria, which are the cause of putresence and fermentation. If the experi- 

 ment on the sulphate of soda tends to establish a relation between fermenta- 

 tion and crystallization, it serves to prove also that these phenomena can 

 take place without the presence of these cryptogamia or infusorial serais, 

 suspended in unfiitered air. This question, which appeared to us finished 

 by the earlier researches of Mr. Schroeder, comes up anew. Cor. SiUiman's 

 Journal. 



ON THE COMPOSITION OF VEGETABLE CELLS. 



M. Fremy has been engaged in some researches on this subject, the results 

 of which he has presented to the French Academy. The nature of the 

 liquids which are found in the vegetable cell have been several times accu- 

 rately determined, but our knowledge of the insoluble portion, or cell walls, 

 is very imperfect. We know that solid matter is deposited on the interior 

 of the cellular membrane, and increases its thickness ; several reagents show 

 that the chemical composition of these layers is often ternary and often 

 nitrogenous, but the insolubility of these bodies in neutral liquids renders 

 their separation at the present time impossible, and prevents their composi- 



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