368 SCIENTIFIC CONGRESS OF CARLSRUHE. 



effects produced by a magnet on the electric light developed at the 

 negative pole in a gaseous medium. Under the influence of the mag- 

 netic fluid, the luminous pencil of the negative pole unites its rays 

 and is contracted into a luminous curve. 



It will be understood that we can here scarcely reproduce more than 

 the substance of each lecture ; such must be the case, therefore, with 

 the interesting experiments of M. Woehler, with silicated hydrogen^ 

 a gaseous compound discovered by himself, and which possesses the 

 curious property of being spontaneously inflammable, like phosphor- 

 ated hydrogen. The mode of preparing this silicated hydrogen does 

 not differ from the general process followed in the preparation of the 

 greater part of hydrogenated compounds, and yet no one had bethought 

 himself of taking the siliciuret of a metal pertaining to one of the 

 three first sections, and decomposing it by water and an acid. It was 

 not thought of because the preconceived opinion had acquired preva- 

 lence, that silicium does not form a gaseous compound with hydrogen ; 

 something like fortuity was needed to place the philosopher of Gcettin- 

 gen on the track, and his genius for investigation has done the rest. 



V. 



Coloring matter of bile — Fermentations and putrefactions — A function of arable land — 

 Digestion in the vegetable kingdom. 



The last session of the section of chemistry was held on the 19th of 

 September. As several remarkable facts were communicated, we shall 

 proceed to sum them up in as few words as possible. 



M. Wicke announced that the coloring matter of the shells of eggs 

 offers the strongest analogy to the coloring matter of the bile. By his 

 account, the egg, as yet colorless in the oviduct, acquires its coloration 

 in the cloaca. 



M. Schroeder, director of the School of Commerce at Manheim, re- 

 ported some new observations relative to his ingenious discovery made 

 some yeass ago, on the subject of fermentation and putrefaction ; that 

 these processes do not take place when, instead of leaving the ferment- 

 able matter in contact with the common air, we deposit this matter in 

 air which has been previously made to pass through cotton. (See Journal 

 de Chimie et de Pharmacie, T. XXV, p. 314.) Meats, bouillon, and all 

 sorts of alimentary substances, have been preserved an indefinite time 

 in this filtered air ; the precaution being observed, however, that sub- 

 stances thus treated be first boiled with water. 



On the present occasion, M. Schroeder announced that what he had 

 established with regard to fermentation and putrefaction, might be 

 extended also to crystallization. It was already known that a super- 

 saturated solution of sulphate of soda remains liquid in a vacuum, but 

 takes on the crystallizing process upon the admission of atmospheric 

 air. The savant of Manheim showed that crystallization does not take 

 place if the admitted air has been previously passed through a tube 

 fitted with carded cotton. 



