482 Transactions.— Chemistry. 
them, so each of them— that is, the oil and eamphor—ean only respond to 
their affinities for water; to the water therefore they both keep, for its 
possession they fight. It is a running fight, in which the oil having a 
motion of its own communieates a part of this to the camphor, and so 
appears as the pursuer. 
Summarizing, now, all that we have here arrived at, by way of 
emphasizing the points I consider as fundamental to the theory I have 
proposed, you perceive that I have maintained upon evidence, much of which 
has been experimentally demonstrated, that the movements described by 
camphor occupying a surface of pure water, are neither due to the direct 
impingement of vapour upon such surface, nor yet to any electrical effect, 
but to the production of a compound of camphor with water, which, being 
of an oily nature, spreads upon the surface of the water, and, in the act, 
forces the camphor to describe the movements in question, precisely in the 
same manner that oils generaly, in their flow along the same kind of 
surface, can urge away from them any solid particles resident thereon. In 
the actual process, directly that the camphor touches the water there is 2 
considerable but unequal output of this oil therefrom, and as this does not 
dissolve in the water, nor volatilize, at nearly the speed at which it is 
formed, it spreads principally upon the water, and retaining for the time 
possession of all it thus overruns, it urges and keeps the solid camphor 
away. 
As I have already stated, were the production of this compound equal 
around the camphor, we should not see the camphor move as we have done; 
but this is in the nature of things impossible, as there is certain to be more 
of it made at the instant of immersion upon one side of the camphor than 
upon any other of equal extent, and so an initial movement and direction is 
given to the camphor. When this direction changes, as it frequently does, 
the output of oil has become greater upon a different side, or the cam- 
phor, in its course, has got into contact with its trail; when all movement 
ceases, the whole surface of the water, or at least that within a considerable 
distance of the camphor, has got enfilmed with the oily compound, and the 
camphor thus becomes oil-bound. 
As to the reason why the oil of camphor when in motion, or, indeed, 
any oil in motion, should thus urge camphor about, I have attempted to 
show that this is due to the fact that they have no affinity for each otlier, 
but that each has an affinity for water, and so they have both a tendency to 
keep in contact with it—in fact, they are adhesive in relation to the water, 
but neutral in regard to each other, hence the appearance of direct repulsive 
effect—a kind of effect, which by-the-way, I believe to be always due to 
secondary action, 
