382 Scientific Intelligence. — Chemistry. 



1 1 . Action of Potash on Organic Materials. — The success of 

 Vauquelin in converting pectic acid to oxalate of potash, by heating 

 the former in a crucible with potash, induced Gay Lussac to attempt 

 the conversion of other organic matters to oxalic acid by a similar 

 process. 



Five grains of cotton, were put into a platina crucible with twenty 

 five grains of alcoholic potash, and a litde water, and the mixture 

 heated over an alcohohc lamp. The cotton resisted the action for 

 some time, but at length yielded, softened, swelled, and evolved hy- 

 drogen. It was necessary to stir the mass continually. When the 

 action is over, the mass is dissolved in a little water and slightly su- 

 persaturated with nitric acid ; it then gives with nitrate of lead, an 

 abundant precipitate, which treated by hydro-sulphuric acid, produces 

 beautiful crystals of oxalic acid. With the nitrate of lime, a volumin- 

 ous precipitate is had of oxalate of lime. 



Wood saw dust gave a similar result. 



Sugar, starch, gum, and sugar of milk, treated with potash, fur- 

 nished in like manner oxalate of potash. 



Tartaric acid also underwent this remarkable transformation, with- 

 out tumescence, blackening or giving out any considerable portion 

 of hydrogen. 



Citric and mucic acid produced much oxalic acid. 



Silk, treated with potash, afforded oxalic acid, with a disengage- 

 ment of hydrogen. 



Uric acid and gelatine also furnished it. Indigo did not. — Ann. 

 de Chimie. Aout, 1829. 



12. Composition of the Atmosphere. — M. Kupffer, in a letter to 

 Arago, states, that in Civilized Europe it might be foreseen that any 

 slight difference of composition in the air would be soon destroyed by 

 the winds, as those countries are but a few hundred leagues apart ; 

 but Kazan, which is bounded on one side by an uncultivated country, 

 and on the other by the immense steppes and forests of Siberia, 

 where there is no vegetation during the greater part of the year, 

 might be imagined to have an atmosphere somewhat different from 

 the rest of Europe. Employing the Eudiometer of Volta, 198 parts 

 of atmospheric air, mingled with 99 of hydrogen, gave constantly 

 171 to 172 parts after detonation, which gives 20. to 21.2 of oxy- 

 gen in 100 parts of air. The greatest care was observed with re- 

 gard to temperature and pressure. — Idem. 



