546 Intelligence and Miscellaneous Articles 



at all altered. Other analogous experiments might be given, and in 

 all instances the result may be predicted according to the solubility 

 of the substances. 



It is true that the increase of pressure, which it is customary to 

 regard as a character of osmose, is wanting in this experiment. In 

 order that this ma}' take place, it is necessary to render the inter- 

 mediate layer fixed. For this purpose a porous vessel is saturated 

 with the liquid intended to act as septum, and the experiment is 

 made as if the porous vessel were the septum, the liquid which mixes 

 most readily with the intermediate liquid being in preference placed 

 outside, so that the principal osmotic movement may be more ap- 

 preciable from the accumulation of liquid in the osmometer. 



When the porous vessel is impregnated with castor oil, filled with 

 water and immersed in alcohol, the osmose is towards the water ; 

 while in a vessel not charged with oil, the principal movement is in 

 the contrary direction. 



The absorption of a liquid by a tissue is the inverse of the solution 

 of a solid by a liquid. Animal membrane, by virtue of the capability 

 of absorbing water and mixing it with other liquids, is comparable 

 with liquids themselves ; but with the advantage that it may be fixed 

 between two liquids without being separated and dispersed, as in the 

 case of liquids with which a porous vessel is saturated. 



The direction of the osmotic movement may be predicted equally 

 well for porous vessels or animal membrane when the rapidity with 

 which they are traversed by the respective liquids is known. The 

 rapidity of filtration is not always proportionate to the mobility of 

 the liquids. Membranes and even porous clay vessels are per- 

 meated by water more readily than by alcohol, notwithstanding the 

 far greater fluidity of the latter. 



M. Lhermite considers that his experiments furnish an evident 

 demonstration of the error into which Mr. Graham has fallen in 

 attributing osmotic motion to the chemical decomposition of the 

 membrane, and in supposing that the motion always carries the acid 

 towards the base. M. Lhermite has indeed found that a solution 

 of oxalic acid, which produces the greatest effect, is a conservative 

 agent ; while, on the other hand, with a solution of alkali in alcohol 

 and a very dilute solution of acid in water, the base is carried towards 

 the acid through either animal membrane or porous clay impregnated 

 with castor oil. — Cowptes Rendus, No. 25, 1855. 



ON THE LUMINOUS COAT OF THE INDUCTION SPARKS OF RUHM- 

 korff's APPARATUS. BY T. DU MONCEL. 

 When examining these sparks in the dark, the author observed 

 that they are surrounded with a greenish-yellow luminous coat, the 

 thickness and form of which varies according to the strength of the 

 current, and the nature of the wires forming the poles ; when the 

 sparks are not very long, however, the luminous coat is almost 

 always of an oval form. It appears to belong principally to the 

 negative pole, and is of a reddish colour on the side of this pole. It 

 is remarkably intense, and resembles a flame when the poles are 

 moistened with an essential oil, and its connexion with the negative 

 pole is also then very distinct. 



