Intelligence and Miscellaneous Articles. 147 



observation are too great. — Zeitschrift fur pliys. Ohemie, vol. ii. 

 p. 206; Beibldtter der Physilc, vol, xiii, p. 134. 



SOME OBSERVATIONS ON THE PASSAGE OF ELECTRICITY 

 THROUGH GASES AND VAPOURS. BY DR. NATTERER. 



The experiments were made with the aid of an induction appa- 

 ratus, and special regard was had to the sparking distance of the 

 electrical discharges, to their luminosity, and to the extension of 

 the glow-light which occurs at the negative electrode under dimin- 

 ished pressure. It appears that these three phenomena, wmich are 

 characteristic for each individual gaseous body, are in relation with 

 the number of atoms in the molecule, and with the molecular 

 weight. — Sitzungsberichte der Wiener AJcademie, June 21, 1889. 



ON THE ELECTRICAL RESISTANCE OF INSULATORS AT HIGH 

 TEMPERATURE. BY DR. H. KOLLER, 



This is a continuation of a paper by the same author on the 

 passage of electricity through very bad conductors. It forms two 

 parts. 



In the first, the author investigates the connexion between the 

 electrical conductivity of some liquid insulators, and their fluidity 

 at various temperatures ; it was found that the course of these two 

 properties is parallel, but not proportional. The conductivity 

 always increases more rapidly than the fluidity, so that, for instance 7 

 with petro]enm ether a twelvefold increase of the conductivity 

 corresponds to only a threefold increase of the fluidity. The con- 

 ductivity of those substances exhibits the greatest increase when 

 their fluidity also increases most strongly with the temperature, 

 Castor-oil, for jinstance, conducts 350 times better at 132° than 

 at 20°, while between these two limits its fluidity increases by 

 only 43 times. 



The second part deals with the gradual change which an imper- 

 fect dielectric experiences in consequence of rise of temperature. 

 The author concludes, partly from Hopkinson's and partly from 

 his own experiments, that the first effect of the increase of an 

 imperfect dielectric consists in the fact that it begins to form 

 residues. The formation of the residue is at first of very short 

 duration, but with increase of temperature extends over a longer 

 interval of time, and the residues developed adhere in accordance 

 with this continually more firmly to the dielectric. At still higher 

 temperatures they are rapidly altered into a form in which a reverse 

 change with free electricity is only possible with difficulty and with 

 great loss : and is finally not possible at all. 



The experimental result is that in a condenser formed of the 

 dielectric in question the amount of residue which can be demon- 

 strated — that is, that which neither takes part in a discharge of 



