Intelligence and Miscellaneous Articles. 159 



termined, according to the above formula, from the friction-constant, 

 to be 4-7. 



v 

 By multiplying the proportional numbers — by 4*7, the values of 



v in the penultimate column are obtained, which agree with the 

 numbers in the last column, calculated b}^ Kopp, as well as can in 

 general be expected in experiments of this sort. 



The molecular volume of free hydrogen, 4'7, is less by more than 

 half than 11*0, the value calculated from its liquid compounds. 

 The author endeavours to account for this in the following manner. 

 If molecules are spheres surrounded with envelopes of aether of 

 variable density, two such molecules, on central impact taking 

 place, will probably act on each other as soon as they arrive at a 

 distance from one another equal to the sum of the radii of the actual 

 sphere of action. The action lasts until the vis viva is reduced to 

 zero and reversed. Molecules with greater velocities, in the gaseous 

 state, will approach nearer to one another, and reciprocally pene- 

 trate with their aether envelopes more deeply than molecules with 

 lower velocities, in the liquid state. Hence in the former case the 

 radius of the apparent sphere of action, consequently the molecular 

 volume, must be smaller than in the latter. 



To the same assumption of a variable sphere of action we are 

 conducted, as first remarked by Director Stefan, by the fact that 

 the friction- constant is proportional not to the square root of the 

 absolute temperature, but to another power of the same, which, ac- 

 cording to the experiments of A. v. Obermeyer and the author, is 

 greater than \ and at the highest is =1. 



A second basis of explanation may, according to the view of 

 Lothar Meyer, lie in the circumstance that, in determining the mo- 

 lecular volume from the density of the liquid compounds, with them 

 the empty space is measured which is open to the atoms for their 

 motions, while, from the magnitude of the obstruction which one 

 particle constitutes for another, only the volume of the gas particles 

 themselves is determined. 



Experiments with air under very low pressures led to this result 

 — that while the pressure diminished from 754 to O03 millim. the 

 friction- constant became less by only about one half of its initial 

 value, from which it may be seen how proportionally great must be 

 the quantity of gas which remains in a very good vacuum, since it 

 can convey quantities of motion so considerable. This is in excel- 

 lent accordance with the kinetic theory of gases, according to which, 

 in a cubic centimetre of air of one millionth of an atmosphere pres- 

 sure, nineteen billion molecules are still present. — KaiserlicheAka- 

 demieder WissenschafteninWien, math.-naturw. Classe, July 1, 1878. 



ON THE DEPOLARIZATION OF THE ELECTRODES BY THE SOLU- 

 TIONS. BY M. LIPPMANN. 

 It has long been known that certain salts possess a depolarizing 

 property. The first pile with a constant current, constructed in 



