376 



Intelligence and Miscellaneous Articles. 



In the course of the preceding research the rarefaction was 

 pushed still further, and 



(c) The outer tube was again dark, the inuer one luminous ; so 

 that to the eye this third stage was like the first one. 



The more perfect vacuum exerts therefore no screening action ; 

 it has lost the power of conducting the electrical current. — Wiener 

 JSerichte, January 9, 1880. 



ON THE FORMATION OF OZONE BY THE CONTACT OF AIR WITH 

 IGNITED PLATINUM, AND ON THE ELECTRICAL CONDUCTIVITY 

 OF AIR OZONIZED BY PHOSPHORUS. BY PROFS. ELSTER AND 

 GEITEL. 

 The authors sum up the results of their investigations in the 



following terms : — 



(1) Incandescent surfaces of platinum ozonize the surrounding 

 air, even when combustions are excluded. 



(2) "When air is ozonized by contact with moist phosphorus 

 it is seen to conduct electricity in the same manner as the gases of 

 flame do. 



(3) It could not be found that this process of ozonization had 

 any electromotive force, or that the air which had been subject to 

 it had any unipolar conductivity. 



(4) The mere presence of ozone already formed, as well as the 

 production of clouds from ammoniacal salts in the vicinity of phos- 

 phorus, are not connected with the origination of the conductivity 

 of the surrounding air, or at any rate only to a subordinate extent. 

 — Wiedemann's Annalen, March 1890. 



NOTE IN CONNEXION WITH DROPPING-MERCURY ELECTRODES. 

 BY J. BROWN. 



In the Zeitschrift fur jphysiJcalische Chemie, iv. p. 577, there is a 

 reference by Prof. Ostwald to my paper on " Helmholtz's Theory 

 of Mercury-dropping Electrodes," communicated to the Philoso- 

 phical Magazine for May 1889 by Dr. Lodge, as secretary to the 

 Electrolysis Committee of the British Association. 



Prof. Ostwald, however, considers only one of my experiments, 

 viz. that which deals with the current in a wire connecting the 

 dropping mercury with the mercury resting on the bottom of the 

 vessel containing the electrolyte in which the drops form. My 

 experiment shows that this current varies in a direction inverse to 

 the change of resistance of the electrolyte, and is therefore con- 

 ducted by the electrolyte, and does not consist of charges carried 

 down by the drops as assumed by Helmholtz. 



It is perhaps unnecessary to refer to Prof. Ostwald's criticism 

 further than to point out that his method of explaining away my 

 conclusion is inconsistent with the fact brought forward by me, 

 but apparently not considered by Prof. Ostwald, that the current 

 flows just the same whether the drops fall into the resting mercury 

 or not, provided they form in the electrolyte in contact with the 

 resting mercury. 



