Physics and Chemistry. 219 
was stopped by a drop of liquid at any place in its bore. In this 
manner, every displacement of the air cylinder contained in the 
middle portion of the tubes must displace the two drops of liquid 
at its extremities in the same direction. One end of the plug was 
now exposed to a constant source of heat, the other being left 
cold or artificially cooled. Then without exception there appeared 
a slow displacement of the air column in a direction through the 
plug, from the cold to the heated end, sometimes quicker, some- 
one 
the other. Spongy platinum, spongy palladium, gypsum, char- 
coal, silicic acid and calcined magnesia, were the subject of experi- 
ment in the manner described. The detail of these experiments 
is given by the author in full, which cannot well be presented in 
abstract. From these experiments, made with the most hetero- 
erty of porous bodies, when in the form of diaphragms, to draw 
lar, hitherto unknown phenomenon; and is properly called by the 
author thermodiffusion. Dufour * has already made diffusion ob- 
servations the converse of these and in harmony with them. He 
menon.— Phil. Mag., July, 1873, p- 55, and Pogg. Ann, 
elxvili, pp. 302-311. ae 
[The influence of heat on the diffusion of gases has an illustra- 
FR el sis; by 
RaNK H. Srorer, A.M. Part IL. pp. 113-224. (John Allyn, 
Boston, 187 3.)—This second part of Professor Storer’s important 
* Archives de Genéve, Sept., 1872, pp- 10, ll. 
