254 Scientific Intelligence. 



thermometers to have acted as thermo-dynamometers rather than 

 thermoseopes. While the crystals were forming in the first 

 refrigerator, the radiation from the bnlb was nentralized by the 

 latent heat given out by the chloroform in crystallizing, whereas 

 in the warmer refrigerator the crystals did not form, and radia- 

 tion alone was active. Alcohol and sulphuric ether thermometers 

 were used, which were checked by thermometers containing dry 

 hydrogen at four different pressures. — Comptes Rendus, May 30, 

 Nature, June 9, 1892. j. t. 



8. JVeio method of determining the specific inductive capacily 

 of a dielectric— F. T. Trouton and W. E. Lilly point 

 out that the comparison between the energy of a condenser 

 charged with a certain quantity of electricity, first as an air con- 

 denser and secondly Math a dielectric sheet between the plates, 

 shows that the energy in the first case is greater than in the 

 second, and therefore the dielectric sheet will be drawn in between 

 the plates ; for the electric energy of the system being less after 

 the introduction of the dielectric than before, work must have 

 been done by the electric forces during the operation. The 

 amount of this force depends on the specific inductive capacity 

 of the dielectric, and by observing this force the specific induc- 

 tive capacity may be determined lor any given substance. The 

 authors describe a method of measurement, and show its applica- 

 bility.— Phil. Mag., June, 1892, pp. 529-532. j. T. 



9. Action of the Electric discharge on Gases and Vapors. — 

 C. Ludeking has made a number of experiments to determine 

 whether electrolysis takes place in the action of the electric dis- 

 charge on gases and vapors. He concludes that " some of the 

 phenomena noted were in part due to true electrolysis. Others 

 seem to be ' thermolysis,' that is the compounds are simply dis- 

 sociated by the heat of the discharge. The predilection of the 

 atoms, thus liberated, for electricity of different kinds would 

 make them, like pith balls, fly to the pole having the charge 

 opposite their own, and thus give the entire phenomenon the 

 appearance in all respects of a true electrolysis, w T hile in reality 

 there is the greatest possible difference." — Phil. Mag., June, 1892, 

 pp. 521-528. J. T. 



10. Ratio between the Electromagnetic and Electrostatic Units. 

 — A new determination has been made by M. H. Abraham of 

 the value of v. The method employed was that of measuring 

 the capacity of a plane condenser with guard ring in both sys- 

 tems. The value obtained was v = 299 - 2 X 10 8 . — Comptes Rendus, 

 June 7, 1892. j. T. 



11. Influence of Electrification on Cloud Condensation. — Mr. 

 John Aitken has studied this subject, using a steam jet — and 

 finds that the mere presence of an electrified body has no influ- 

 ence on the steam jet. In order to produce the increased density 

 the water particles in the jet must be electrified either by direct 

 discharge, or by an inductive discharge, effected either by means 

 of a point or a flame. The increased density produced by electri- 



