220 Intelligence and Miscellaneous Articles. 



3. Au anode surface is far more feebly attracted, and therefore 

 far more feebly charged, than a kathode surface. 



If the two infinite plane electrode surfaces are opposite each 

 other, they are equally attracted only so long as electricity is in 

 equilibrium. If the glow-discharge passes between the surfaces, 

 the charge of the anode is feebler than the charge of the kathode 

 by the excess of free positive electricity which is met with in the 

 gas traversed by the current. 



4. For the normal density in which the negative glow-light can 

 spread freely over the kathode, the electrical force at the kathode 

 decreases with decrease of pressure, and is less for hydrogen than 

 for nitrogen, in conformity with the well-known laws for the 

 striking- distance. Hence at normal density the excess of free 

 positive electricity mentioned under (3) diminishes with increase 

 of pressure. 



5. The actual electrical charge of the gas which takes place in 

 the glow-discharge brings with it an increase of the hydrostatic 

 pressure, and therefore, under ordinary circumstances, produces 

 eddy currents which flow between limited electrodes from the 

 anode to the athode, and may explain the frequently observed 

 transport of matter in the direction of the positive current. — 

 Wiedemann's Annalm. No. 1, 1892. 



ON A NEW METHOD OF DETERMINING THE MAGNITUDE OF 

 MOLECULES. BY G. JAGER. 

 If it be assumed that molecules are minute droplets, which are 

 formed from larger ones by impact against and repulsion from solid 

 walls, and which ultimately acquire a definite mean value for a given 

 temperature, seeing that a division is only possible as long as the 

 vis viva with which the drop strikes against a wall is greater than 

 the work necessary for the division ; in this case we obtain a limit- 

 ing value for this magnitude. If it be assumed that all droplets 

 are of the same size, then the drops from which they are formed 

 must be at least twice as large. We have therefore to determine 

 the increase of surface when a sphere is divided into two equal 

 parts of spherical form. This, multiplied by the capillary con- 

 stant a, gives the w r ork 47r(2—^/4y 2 a, if r is the radius of the 

 partial spheres. This work must be equal to ^Trr 3 pw?; that is, the 

 vis viva of the original sphere, if p is the density of the liquid, and 

 w 2 the mean square of the velocity. From this we get r=l-24a/pu> 2 

 as radius of the molecules. The values obtained by this method 

 agree very well with the results of other methods. 



Water 5i\L0-9 centim. 



Ether 76 



Alcohol 52 



Methylic alcohol .... 37 „ 



Carbon bisulphide . . 73 „ 



Chloroform 80 „ 



Aceton 31 „ 



— Wiener Berichte, vol. c. p. 1122 (1891); from Beiblatter der 

 PhysiJc, vol. xvi. p. 345 (1892). 



