78 Intelligence and Miscellaneous Articles. 



Between both sides of the inner porous cylinder there is obviously 

 a difference of pressure equal to the pressure of vapour at the 

 temperature of the experiment. The air goes from the interior 

 of the body (in the first experiment) towards the outside, and the 

 vapour in the opposite direction ; but the latter is absorbed by the 

 porous sides, and we have first of all a decrease of pressure, which 

 rapidly vanishes, since the vapour diffuses, according to Graham's 

 law, more rapidly than dry air. The author explains in an ana- 

 logous manner the converse experiment of Dufour. Similar experi- 

 ments of his own, which essentially agree with those of Dufour, 

 have confirmed this explanation. 



The author applies the diffusion of gases and vapours through 

 porous bodies to the construction of a hygrometer, or gas-indicator. 

 The hygrometer in question consists of a vessel (cylinder) which is 

 filled with water, connected with a water-manometer, and covered 

 by a porous plate. If this apparatus is brought into free air, the 

 manometer soon rises, and the higher, the further the surrounding 

 air is from the point of saturation with aqueous vapour. 



The manometer falls when the vessel is filled not with water but 

 with sulphuric acid, and thus dry air is present. The change of 

 pressure is a function of the temperature, and is different for 

 different porous plates. The apparatus can be easily graduated. — 

 Beibldtter cler PhysiJc, No. 9, 1887 (from Journal of the Russian Phy- 

 sical and Chemical Society for 1886). 



ON ELECTRICAL TRANSPORTATION IN LIQUIDS. 

 BY S. TERESCHIN. 



The transport of liquids in capillary tubes by constant electrical 

 currents has hitherto been investigated for comparatively small 

 electrical forces. 



At the suggestion of Prof. Quincke, instead of a constant voltaic- 

 current, I used the electrical current which flows to earth from the 

 inner coating of a Leyden jar through the column of liquid, and 

 through a sensitive reflecting- galvanometer. The outer coating 

 of the Leyden jar of flint glass was put to earth. The inner 

 coating was kept at corstant potential by rotating a Holtz's machine ; 

 and this electrical potential P was measured by a Eighi's electrometer 

 with bifilar suspension, in electrostatic units of the C.G.S. system. 

 By multiplying these numbers by 300 we get the electrical potential 

 expressed in volts. 



In these observations I used an apparatus of the same construc- 

 tion as that used by Prof. Quincke; it had a flint glass tube 0*738 

 millim. in diameter, which was inclined at an angle with 

 the horizon. The distance a of the electrodes was 289 millim. 

 The third platinum wire interposed between the two former, made 

 it possible to diminish to one half the length of column of the 

 Liquid traversed by the current. 



The results collated in the following tables give the observations 

 for water, methylic and ethylic alcohols. The first column gives 



