472 Intelligence and Miscellaneous Articles. 



THE HEATING OF THE GLASS OF CONDENSERS BY INTERMITTENT 

 ELECTRIFICATION. BY J. BORGMANN. 



The author takes two bundles of 30 cylindrical condensers, each 

 consisting of a glass tube 46 crn. in length and 5 mm. in diameter ; 

 each tube was coated externally with tinfoil, and filled with copper 

 filings, and a copper wire inserted, the ends being closed with 

 paraffin or shellac. Each thirty tubes are formed into bundles, all 

 the outsides and insides being severally connected. One bundle was 

 also coated on the outside with tinfoil to improve the conductivity. 

 These two bundles of condensers were placed respectively in two 

 large air- thermometers. Each reservoir consisted of a glass tube 

 of about 50 cm. length and 4*5 cm. internal diameter, which was 

 surrounded by another tube of the same length and 7 cm. diameter. 

 Through the brass ends of the reservoirs passed on the one hand 

 the electrodes, and on the other the limb of the manometer. The 

 manometer filled with naphtha consisted of three limbs, of which 

 two were connected with the two reservoirs of the air-thermometer. 

 The charging was effected by means of a Ruhmkorff, and was 

 measured by a Siemens electrodynamometer. Notwithstanding its 

 better external conductivity, the bundle C was more heated than 

 the other, A. 



If e is the deflection of the electrodynamometer in divisions of 

 the scale, Aa and Ac the displacement of the naphtha in the mano- 

 meter in millimetres, which measure the quantities of heat, it was 

 found that 



e 345 280 147 101 \e 343 159 



A c H-3 9-84 4-84 2-9 | A A 10-8 5-2 



e/A 30-5 28-4 32-4 34*8 e /A 31*7 30-6 



It follows from this that the heatings of the condensers are 



approximately proportional to the square of the difference of 



potential of the coatings. — Beibl'dtter cler Physik, 1887, p. 55. 



ON THE CHEMICAL COMBINATION OF GASES. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, Riga, April 8, 1887. 



In the April Number of the Philosophical Magazine for this 

 year Prof. J. J. Thomson complains that I have misunderstood his 

 theory of the Chemical Combination of Gases. After a repeated 

 study of the paper, I must confess that Prof. Thomson is in the 

 main right. As in my criticism I have done Prof. Thomson an 

 injustice which I am not able entirely to repair, I will not dwell 

 upon the injustice which he in the heat of his defence has done me 

 in his answer, the more so as it has no scientific, but a mere per- 

 sonal interest. 



Have the kindness to insert the above explanation in the next 

 Number of your Magazine. Yours truly, 



W. OSTWALD. 



