256 , Prof. Schonbeiu on the Connexion of 



oxidatiou ; and it is evident from this fact, that the catalysis of 

 the said acid depends first of all upon a change of condition 

 effected by the carbon in a part of its oxygen. 



According to my observations, light also effects the catalysis 

 of permanganic acid, but much more slowly than charcoal. And 

 that the acid, freed as much as possible from water, decomposes 

 even at a moderate temperature into peroxide of manganese and 

 common oxygen is a well-known fact, and is the reason why this 

 acid has not yet been obtained in an anhydrous condition. 

 Should we ever be successful in preparingdry permanganic acid, 

 it will very probably comport itself like anhydroixs nitric acid, or 

 like hypochlorous acid ; that is, three equivalents of its O will 

 be just as readily transformed into 0, as nitric acid or hypo- 

 chlorous acid allow the change of one equivalent of their 0. 

 Hence free permanganic acid might, even at a comparatively 

 moderate elevation of temperature, decompose into peroxide of 

 manganese and common oxygen, just as under the same circum- 

 stances anhydrous nitric acid or hypochlorous acid decompose, 

 the one into NO^ + 20 and 0,the other into MuO + (C])and *. 



I will remark on this occasion, that in my opinion the ulti- 

 mate reason why many an oxygen compound is obtained with 

 such difficulty, or not at all, in an isolated condition, is to be 

 sought for in the ease with which all or a part of the O contained 

 in it passes into 0. Nitric acid = N0'^ + 30 could not for a 

 long time be obtained anhydrous, because its third 0-equivalent 

 is changed into at a proportionately low temperature, and 

 hence arises its decomposition into NO'' and common oxygen. 

 The chloric, bromic, permanganic, ferric acids, &c., have up to 

 this time not been obtained in an isolated condition, precisely 

 on account of the ready conversion of a part of their O into 0. 



All the catalysing substances hitherto discussed are compounds 

 the whole or part of whose proportion of oxygen may be assumed 

 to be in the condition. But there exists a great number of 

 compounds which contain the oxygen as 0, and from which it 

 can be separated neither by heat nor by light. Water, potash, 

 oxide of lead, &c. are oxygen compounds of this kind, and none 

 of them have been hitherto catalysed by means of a ponderable 

 substance. According to the views developed above, such a 

 catalysis could only be effected by an agent which was able to 

 convert the of potash, water, oxide of lead, &c. into 0. 



We possess such an agent in the galvanic current, by which 



• Since this paper was written, which was done in March, M. Thenard, 

 jun. has published a notice, in which he announces that he has suc- 

 ceeded in preparing permanganic acid in an anhydrous condition, and that 

 it is decomposed into peroxide of manganese and common oxygen with 

 extreme ease. 



