Intelligence and Miscellaneous Articles. 547 



bergen exhibits the greatest analogy with the dust previously ob- 

 served by M. Xordenskiold on the snows of Greenland, and de- 

 scribed by him under the name of kryokonite. These two precipitates 

 have probably a common source, at least as regards their metallic 

 and magnetic portion, composed of iron, cobalt, and nickel, the 

 cosmic or meteoric origin of which does not appear contestable. 



M. Nordenskiold has also found analogous ferruginous particles 

 in hailstones collected at Stockholm. It seems, therefore, well 

 established by these various observations, that in the polar regions 

 there often falls with the atmospheric precipitation a cosmic dust 

 containing the metals iron, cobalt, and nickel, phosphoric acid, and 

 a carbonaceous organic powder. M. INTordenskiold remarks on the 

 interest this discovery may have for the theory of shooting-star 

 showers, aurorse boreales, sun-haze, &c, and on the part which 

 may be played in the economy of our globe by this importation, 

 slight, it is true, but perpetual, of new matter to its surface. 



Before quitting this interesting subject, we will remind our 

 readers of the results recently obtained by M. Tissandier in his 

 study of the atmospheric dust gathered at Paris*, which was always 

 found to contain a notable quantity of iron. — Biblioiheque Univer- 

 selle. Archives cles Sciences, Phys. et Nat. Nov. 15, 1874, pp. 282-284. 



ON THE PASSAGE OF GASES THROUGH LIQUID FILMS. 

 BY. DR. F. EXNER. 



That gases can penetrate a soap-film has been already shown by 

 Draper and Marianini, but without making quantitative determina- 

 tions or going into the causes of the phenomenon. In the present 

 memoir are contained quantitative determinations with air, illumi- 

 nating gas, N, O, H, CO 2 , H 2 S, and NH 3 . From these is deduced 

 the law that the velocities of diffusion of gases are proportional to 



the expression — r=, in which C signifies the coefficient of absorp- 



V o 

 tion of the gas for the liquid of which the film consists, and 3 the 

 deusity of the gas. For the diffusion-velocities of the gases ex- 

 amined, putting that of air=l, the following numbers were found 

 b vation : — 



N=0-86 Illuminating gas =2-27 CO 2 = 47*1 NH 3 = 46000 



= 1-95 H =3-77 H 2 S=165 



Within these extraordinarily wide limits, between 0*86 and 46000, 



the observations are in perfect accord with the formula -jj. Ex- 

 periments were also made for the purpose of ascertaining the abso- 

 lute velocity of diffusion. These gave for the diffusion of H in air 

 through a soap-film, that in 1 minute 1*88 cubic centim. H and 

 0*50 cubic centim. air simultaneously pass through ] square cen- 

 tim. of the film. — Kaiserliche Akademie der Wissenschaften in Wim, 

 Sitzung der maih.-nat. Classe, November 5, 1874. 



* Comptes Rendus de VAcad. des Sciences, March 23, 1874. 



