234 



SCIENCE PROGRESS 



about im'silica vessels, the alkali of a glass vessel retaining at 

 least a part of its activity in presence of an acid chloride. 



(e) Mechanism of the Transference of a Mobile Hydrogen 

 Atom. — It has been shown above that solutions of nitro- 

 camphor in chloroform, benzene, carbon disulphide and ether 

 do not undergo isomeric change unless a (basic) catalyst is 

 also present. In acetic acid, however, the change proceeds 

 rapidly without the addition of any such agent, and indeed 

 under conditions such that a nitrogenous base, if present, would 

 be rendered inactive ; similar conditions probably prevail also 

 in alcohol and in water, although it is not possible in these 

 cases to employ an anti-catalyst to eliminate the impurities. 1 

 It can, however, be proved by experiment that the catalytic 

 action of water is much greater than that of any basic im- 

 purities it may contain, and whatever action is observed must 

 therefore be attributed to the water itself. It appears then 

 that the isomeric change of nitrocamphor can be brought about 

 not only by alkalis such as NaOH and by bases such as NH 3 , 

 but also by acids, by water, by alcohol, and by acetic acid, 

 though not by ether or by hydrocarbon solvents. All the 

 active compounds are characterised by the presence of a 

 hydrogen atom which is displaceable by metals, and it is 

 perhaps to this that they owe their activity. 



It may further be noticed that in the case of each catalyst 

 the isomeric change can be accounted for by the production 

 and decomposition of an intermediate additive compound, eg. 



/H 



C s H l4 < 



* 



CO 



c 



C 8 H 14 < 



-H 



^N 



CO 



o 

 o 



CsH, 



^N< 



'H 



<N< 



CO 



c 



/ 



II 



C 8 Hi 4 < 



^N< 



'O.C1 



O. H 



'O. OH 



-O . H 



-O.O.CO.CH 

 O.H 



* 



C S H, 



'O 



^N.OH 



CO 



* 



Normal nitrocamphor 



CO 



Additive compounds 



Pseudo-nitrocamphor 



1 Mere neutralisation would be ineffective, and substances such as carbonyl 

 chloride and acetyl chloride are at once decomposed by water and alcohol. 



