148 Intelligence and Miscellaneous Articles. 



short duration, nor is so similar to heat that it cannot change into 

 dielectric displacement— increases on heating from approximately 

 zero to a maximum. It decreases after this, and with the occurrence 

 of perfect conduction it entirely disappears. — Sitzungsberichte cler 

 Wiener Akademie, June 21, 1889. 



ON THE RESISTANCE TO DISRUPTIVE DISCHARGE OFFERED BY 

 GASES UNDER HIGH PRESSURES. BY MAX WOLF. 



At the instance of Prof. Quincke the author attempted to ascer- 

 tain what resistance certain gases offered at high pressure to the 

 passage of the electrical spark. In other words, the difference of 

 potential of two spherical surfaces was determined at the moment 

 of the discharge, for different gases and at various pressures 

 greater than one atmosphere. In this a method was used similar 

 to that used by Quincke for determining striking distances in insu- 

 lating liquids. It was to be expected that under higher densities 

 the irregularities in the discharge occurring under smaller pressures 

 must be less prominent. 



The conclusions arrived at are as follows : — 



(1) The electrical force which produces the disruptive discharge 

 in various gases between spherical surfaces of 5 centim. radius and 

 at a distance of 0-1 centim. increases proportionally to the pressure 

 for pressures between 1 and 9 atmospheres. 



(2) The increase of the electrical force for simpler gases (oxygen, 

 hydrogen, and air) is inversely proportional to the mean path of 

 the gas-molecules. 



(3), "With carbonic acid the product from the increase in the elec- 

 trical force into the mean path for an increase of pressure for one 

 atmosphere is considerably smaller (almost one half) that of simple 

 gases. 



(4) One or more discharges are necessary until the resistance of 

 a gas is attained, and the resistance is at first so much the less than 

 in the later discharges, the higher is the pressure on the gas. — 

 Wiedemann's Annalen, vol. xxxvii. p. 300 (1889). 



THE NATURE OF SOLUTIONS. BY S. U. PICKERING. 



On pages 36-38 of this Magazine Prof. Arrhenius publishes a 

 criticism of my paper on this subject. I venture to think that it 

 is somewhat rash of Prof. Arrhenius to attack a paper which has 

 not yet been published, and of which only a short abstract, destitute 

 of all experimental data, has as yet appeared in print. If he will 

 wait till the paper be published in full (and it may be some months 

 yet before it is so) he will, I think, find that several of his criti- 

 cisms are mistaken, and that the others have already been answered. 

 If otherwise, I shall then be ready to answer him on any point 

 which he may raise. 



July 2, 1889. 



