Conditions of Molecular Action. 373 



The nascent state of Bodies. — The great energy of bodies when 

 recently formed, and before their evolution is completed, may 

 be partly due to their greater concentration at this time ; but 

 it seems likely that the freedom of their particles, at the moment 

 of their formation, from all taint of other matter may enable them 

 to put forth all the molecular vigour they possess, and assist 

 them to overcome obstacles which would otherwise prevent them 

 from forming a chemical combination*. 



Catalytic actions. — It will have been noticed that, under the 

 head of each condition of molecular action, allusion has been 

 been made to some form or other of catalytic action. This term 

 has been made to include a very wide range of both physical and 

 chemical reactions ; but strictly its use should be confined to 

 those cases in which a substance (the catalyte) brings about che- 

 mical or physical changes without being itself in any way altered. 

 Thus defined, it would apply to all those actions carried on by 

 means of the catalytes which have already been enumerated — the 

 oxidations of ammonia, of alcohols, ethers, essential oils, and 

 other hydrocarbons, and the decomposition of chlorate of potash 

 by means of binoxide of manganese or the sesquioxide of iron. 



When these operations are attentively considered, it will be 

 seen that in all of them the conditions we have already examined 

 are fulfilled. Catalytes are substances having little or no che- 

 mical affinity for the materials upon which they act ; their mole- 

 cules are loosely aggregated so as to be able to act independently; 

 in nearly every case their energy is increased by the cleansing 

 of their surfaces from all taint of other matter. The only re- 

 maining condition, their molecular affinity for the substances 

 acted upon, may be inferred from what has gone before respect- 

 ing the enormous power possessed by several of them of absorb- 

 ing large quantities of certain gases. Upon the hypothesis that 

 catalysis depends purely upon molecular force, it is not difficult 

 to understand why a very small portion of a catalyte is sufficient 

 to produce changes in a large quantity of suitable material : the 

 molecular action once completed upon one part of the substance 

 is not necessarily exhausted. If the substances formed by con- 

 tact with the catalyte have less affinity for it than the original 

 material had, they will readily be given up, the molecular power 

 of the catalyte will be again set free, it will attract fresh portions 

 of the more appropriate material, and the action may go on 

 almost indefinitely. 



* This observation must have at least equal weight in reference to vital 

 as to purely physical molecular phenomena ; and we can hardly doubt that 

 the power of constantly bringing forth newly formed untainted material in 

 the processes of vital growth must have a most important influence in pro- 

 ducing physiological reactions. 



