160 Intelligence and Miscellaneous Articles. 



of mean size, and the commutator be so turned as to close the se- 

 condary circuit, a platinum wire more than 2 metres long and \ 

 millim. thick can be made incandescent for a few instants. Che- 

 mical decompositions requiring great tension may also be shown, 

 as well as physiological effects and a voltaic arc of short duration. 

 In fact, we obtain for a brief ^space the same effects as are produced 

 by a battery of fifty-five to sixty elements arranged in a series. 



The calorific effects produced by this apparatus might be used for 

 firing mines, and the physiological effects for medical purposes. 



In short, the secondary battery with lead electrodes enables us to 

 obtain either powerful temporary effects of quantity from a conti- 

 nuous source of electricity of small quantity, or powerful temporary 

 effects of tension from a continuous source of small tension. 



This concentration of the work of the battery is doubtless only 

 obtained through the intervention of a chemical action, and is 

 effected with the losses inevitable in every organ of change. There 

 is not, as in the case of induction for instance, the direct production 

 of one physical effect by another physical action ; but the final result 

 is none the less an accumulation or a modification of electrical force 

 which can be utilized in certain circumstances. 



These facts show, moreover, the importance of the part which 

 secondary currents must play in electrochemistry, and the applica- 

 tions which may result therefrom. — Comptes Rendas, June 22, 1868. 



ON THE FORMATION OF PEROXIDE OF SILVER BY OZONE. 

 BY F. WOHLER. 



If, through water feebly acidulated by sulphuric acid, the current 

 from a few Bunsen's elements be passed, and if a silver plate be used 

 as the positive electrode, it immediately begins to be covered with a 

 black substance. This substance is peroxide of silver, easily recog- 

 nizable by its property of dissolving in ammonia with a brisk evo- 

 lution of nitrogen. Thus prepared it forms black amorphous crusts, 

 unlike the beautifully crystallizing peroxide which separates from a 

 dissolved silver-salt at the positive pole. 



This mode of formation is interesting, inasmuch as it probably 

 takes place directly from the ozone at the positive pole ; for it was 

 long ago observed by Schonbein, and noted as one of the charac- 

 teristic properties of ozone, that bright silver is superficially changed 

 into peroxide by ozonized oxygen. In the experiments the current 

 was strong enough to form ozone when platinum was used as an 

 electrode ; but when silver was used no trace of any odour of ozone 

 could be perceived ; and it must therefore be assumed that all the 

 ozone is used for the oxidation of the silver. 



After a certain quantity of peroxide has been deposited on the 

 silver, it begins slowly to disengage oxygen ; and simultaneously 

 there is deposited on the negative pole a small quantity of grey amor- 

 phous metallic silver. At the same time there is always a small 

 quantity of silver in solution. These are probably secondary pheno- 

 mena, arising from the action of the sulphuric acid collected at the 

 positive pole, which decomposes the peroxide. — Liebig's Annalen, 

 May 18G8. 



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