402 Intelligence and Miscellaneous Articles. 



tolerably distant catastrophe, they will console themselves by the 

 thought that the things of this world, even the most beautiful, do 

 not appear to be made to last for ever. 



As to the fundamental experiments of Dr. Siemens, they will 

 lose none of their importance in their eyes. The business is 

 to surprise a secret of living nature, one of the laws of the organic 

 world ; and their desire will be that Dr. Siemens may pursue the 

 course in which he has commenced so brilliantly, even though they 

 cannot hope to have a very bright light thrown by it upon their 

 own researches. — Comptes Rendus, October 9, 1882, p. G12. 



ON THE CONNEXION BETWEEN THE GAS-DENSITY AND STRATUM- 

 INTERVAL IN GEISSLER TUBES. BY DR. E. GOLDSTEIN. 



■ Let the total length of a series of immediately consecutive strata 

 of the positive light, of which the first is that which is next to the 

 positive end of the tube, divided by the number of strata, be called 

 the mean interval. The following data respecting this quantity are 

 abstracted from experiments with dry air, hydrogen, and mixtures 

 of the two, under such conditions of the discharge that the strata 

 do not exhibit the to-and-fro vibrating saucer-shapes which escape 

 any precise measurements, but appear in the so-called nebulous 

 forms, which can be brought to a considerably greater degree of 

 stability. In opposition to the generally current view that these 

 clouds represent degenerations and derangements of the proper 

 stratification, I have already* called attention to the far greater 

 probability that they only represent the full development of that 

 phenomenon. The thick cloudy strata stand in precisely the same 

 relation to the thin saucer-like strata as a long-rayed tuft light at 

 the cathode to thin films at first investing the cathode, from which, 

 with diminishing density of the gas, the elongated rays are deve- 

 loped. In order to form a clear conception, I wished, further, to 

 be able to presuppose as known that in cylindrical tubes the 

 stratum-interval increases with increasing width of the tubef, so 

 that, in tubes filled with air, the intervals between the individual 

 strata, when the latter are most distinctly formed, are about equal 

 to the diameter of the tube J. 



If, now, we determine, for cylindrical tubes of different widths 

 inserted in the current-circuit, from an equal number of strata the 

 mean stratum-interval J, J', J", . . . for any two pressures of gas d 

 and S, we obtain constantly 



J<* __ %'& __ J"rf 



in words : — For cylindrical tubes of different widths, the mean 

 stratum-interval constantly varies in the same ratio between the 

 same gas-pressures. Therefore, if, for example, in one of the tubes 



* Wied. Ann, xii. p. 272. 



t Monatsb. cler Akad. Berlin, 1876, p. 294; Phil. Mag. [5] iv. p. 863, 



\ Wied. Ann. xii. p. 272. 



