254 Prof. Schonbein on the Connexion of 



first of all, ou the weaker or stronger resistance which the of 

 these compounds opposes to its transformation into 0, Expe- 

 riment shows that the substance associated with O exercises a 

 great ^influence on the temperature at which this O passes into O. 

 The combined with HO changes^ into at a temperature which 

 lies far under that at which the O associated with PbO suffers 

 the same change. And there are some oxygen compounds whose 

 cannot be transformed into^O, even at the very highest tem- 

 peratures; as, for instance, the O of peroxide of iron (Fe^ 0^ + 0), 

 which 0, under certain circumstances, is so readily transferred 

 to a series of oxidizable substances. 



From reasons which have been repeatedly expre|sed by me, I 

 consider chlorine itself as a compound containing ^O, as peroxide 

 of murium {murium suj;e?-o<Z7/f/) = MuO + O, whose O, just as little 

 as the of peroxide of iron, can be changed by heat into ; 

 for which reason neither the one nor the other decomposes by 

 heat, or furnishes oxygen. But if we bring some substance in 

 contact with MuO + O, which is disposed to form a compound 

 with MuO, as, for instance, HO, KO, &c., the of the peroxide 

 of murium can be transformed, under the simultaneous influence 

 of heat or of light, into 0, under which circumstances HO, 

 MuO (hydrochloric acid) is formed, and common oxygen is set 

 free. 



Certain ponderable agents seem also to act upon aqueous 

 chlorine in a similar manner to light and heat. If, for instance, 

 chlorine gas be allowed at ordinary temperatures to pass through 

 a tube filled with moist charcoal powder, such a large quantity 

 of hydrochloric acid is formed under tolerably strong increase of 

 temperature, that the carbon charged with it gives out in the 

 air thick white vapours. After no long time <^he evolution of 

 heat ceases, but with it the formation of hydrochloric acid, and 

 the chlorine passes now unchanged over the moist charcoal. 

 The production of this acid takes place also with tolerable rapidity 

 if charcoal powder be shaken with chlorine water, in which case 

 a given quantity of the former changes only a determinate quan- 

 tity of the chlorine into hydrochloric acid ; and when this has 

 taken place, the charcoal comports itself in the latter as in the 

 former case, quite indifferently towards chlorine water. This 

 inactivity depends upon a coating of hydrochloric acid which 

 adheres very closely to the particles of charcoal, and can 

 only be removed by an intense red heat. When this is effect- 

 ed, the charcoal again displays its original activity, that is, 

 the capacity of determining even in the cold the formation of 

 hydrochloric acid from chlorine and water, to be again lost under 

 the circumstances already mentioned. The loss of this property 

 may be compared with the loss by platinum of the property of 



