MEMOIR XX. J THE ALLOTROPISM OF CHLORINE. 30 9 



the assumption of the passive state disguising the pres- 

 ence of the electro-negative atom. 



The explanation here given of the phenomena of 

 substitutions involves the position that chlorine when 

 brought in relation with carbon under certain circum- 



o 



stances is thrown into the passive state, the state Cl/3. 

 We naturally look for direct evidence that this is the 

 case. It seems to me that there are many w 7 ell-known 

 chemical facts tending to establish the passive condition. 

 In the first case to which we turn, the chlorides of car- 

 bon, the inactive state is established in a striking man- 

 ner. The affinity existing between chlorine and carbon 

 is apparently feeble ; yet when these bodies have once 

 united the chlorine is brought into such a condition 

 that it has lost the quality of being detected by the or- 

 dinary tests which determine its presence. How strong- 

 ly does this contrast with the case of hydrochloric acid ! 

 A feeble affinity unites carbon and chlorine, an intense 

 affinity unites hydrogen and chlorine ; yet in the former 

 case the chlorine is undiscoverable by the commonest 

 tests, in the latter it yields to them all. And the causes 

 are obvious ; in the one case it is in the passive, in the 

 other in the active condition. 



I have hitherto spoken of the active and passive 

 states as though they were fixed points in elementary 

 bodies, and as though the transition from one to the 

 other were abrupt and sudden. I have done this that 

 the views here offered might be unembarrassed and dis- 

 tinct. But there are many facts which serve to show 

 that the passage from a state of complete activity to a 

 state of complete inactivity takes place through gradu- 

 al steps. Thus, in carbon itself, there are undoubtedly 

 many intermediate stages between the almost spontane- 

 ously inflammable varieties and diamond, which, under 

 common circumstances, is incombustible. Berzelius ad- 



