258 Prof. Schonbein on the Connexion of 



separation of iodine ; yellow prussiate of potash is changed into 

 red ; sulphurous acid into sulphuric acid ; PbS into PbO, SO^ ; 

 indigo dissolved in sulphuric acid is changed into isatine, &c. 



But if the contact loetween phosphorus and common oxygen 

 is indispensable in order that the latter may acquhe the pro- 

 perty of eflFecting these oxidations^ a continuous contact is ne- 

 vertheless not necessary. Oxygen, after it has experienced the 

 specific influence of phosphorus, continues to exhibit an eminent 

 oxidizing property, even after contact between it and the phos- 

 phorus has ceased. 



The accuracy of this statement is manifest from the simple 

 fact, that atmospheric oxygen, which has stood for some time 

 over phosphorus, effects, even after the removal of the latter, all 

 the oxidations which it produced during its presence. On this 

 account we are justified also in assuming that this body possesses 

 the property of allotropizing common oxygen, that is, of changing 

 O into 6. 



We know that electricity causes a similar change of condition 

 in oxygen without the assistance of any ponderable matter ; for 

 under electric influence this gas effects all the oxidations which 

 oxygen, altered by phosphorus, can produce; and in this case 

 also oxygen exhibits its chemical activity, not only during the 

 continuance, but also after the termination of the electric action. 



From these facts it follows that the catalytic influence of 

 electricity and of phosphorus is eff"ected upon oxygen, and con- 

 sists primarily in an allotropic modification of this body. For 

 this reason it may be allowable to speak of an allotropizing influ- 

 ence, instead of a catalytic, or influence by contact. 



It is well known that other simple substances produce an 

 action upon oxygen which may in many respects be compared 

 with that of phosphorus. In this respect platinum is very highly 

 distinguished, although the other noble metals behave similarly. 

 The most surprising action is certainly the union which platinum 

 effects between oxygen and hydrogen, under circumstances in 

 which they would otherwise be perfectly indifferent towards each 

 other. 



In the same way it has long been known that the presence of 

 platinum determines common oxygen to a series of other oxidizing 

 actions ; for instance to the change of sulphurous into sulphuric 

 acid, of alcohol into acetic acid, &c. I have found that oxj-^gen left 

 in contact with platinum turns tincture of guaiacum blue, bleaches 

 moist paper coloured blue by means of indigo solution, &c. ; 

 actions which oxygen allotropized by means of electricity or 

 phosphorus also produces. 



Thenard has already shown that gold, silver, and the rest of the 

 noble metals determine the union of oxygen with hydrogen at 



