as connected with the Theory of Subslitutiom. 341 



^IHieonatituentof organic bodies, without being struck with 

 ()bi9j apparent connexion of that phaenomenon with those of allo- 

 tropism. And though Berzelius, with his customary caution, 

 in^rely insinuates that nitrogen can exist under two forms, the 

 facts which are here developed in relation to chlorine seem to 

 show that that opinion rests on something more solid than 

 conjecture. The iiabitudes of many of the gaseous bodies 

 strengthen this conclusion. Oxygen gas refuses to unite when 

 mixed with hydrogen, precisely in the manner of chlorine ; 

 and it requires a certain modification to be made in the elec- 

 tro-negative element before water or chlorohydric acid can 

 result. 



Just, therefore, in the same manner that so many elemen- 

 tary bodies can put on under the influence of external causes 

 an active or passive condition, I infer as the final result of the 

 experiments brought forward in this memoir, that chlorine is 

 one of those allotropic bodies having a double form of exist- 

 ence ; that, as commonly prepared, it is in its passive state, 

 but that on exposure to the indigo rays or other causes, it 

 changes and assumes the active form ; and that in this latter 

 state its affinity lor hydrogen becomes so great that it decom- 

 poses water without difficulty, as in the experiment which this 

 memoir is designed to illustrate. 



0« the Relation of the preceding Conclusions 'with the Theory 

 i of Substitutions. 



I, Having thus explained the facts which appear to indicate 

 the allolropism of chlorine, I shall now offijr some considera- 

 tions on it& (COBpexion with the theoi'y of substitutions of M. 



Dumas. ! rtlfJfbjo Ico/!" ;(i .iiy>lTf:f!f-l;'>'/ «t'>'' 



Admitting the fact that the electro-negative qualities of 

 chlorine are exalted upon its exposure to the indigo rays, and 

 that the resulting effect is not a temporary thing, but one which 

 lasts for a considerable period of time, as appears to be proved 

 in the Philosophical Magazine (July 1844), we can give a very 

 plain and simple account of the decomposition of water by this 

 gaseous substance under the influence of sunshine. 



Upon the same principle that a mixture of chlorine and 

 hydrogen may be kept in the dark without union for a long 

 time, so may a solution of chlorine in water be preserved. 

 The chlorine is in an inactive state. 



But if anything is done to make the chlorine take on its 

 other form and pass to the active condition ; if, for example, 

 it be set in the sunshine, its affinity for hydrogen is exhibited, 

 and decomposition is the result. 



The qualities thus communicated to the chlorine not being 



