476 Transactions.—Chemistry, 
Evidence of this sort, indeed, is to be had in every exhibition of these 
movements of camphor, for whenever the camphor gets to the vessel's 
side, it remains there motionless, whereas it should (according to the theory 
we are gxamining) rebound therefrom, with great force. 
But apart from and independent of these results, it is, as I conceive, 
very questionable whether any vapour emanating from a substance which is 
of the same temperature as its environment, and in presence of air, has & 
direct repellent effect thereon, However, this is a question of so general a 
character that I cannot well extend the scope of this paper so far as to 
take it into consideration now, but if you will allow me I will trench upon 
it so much as to inform you of a few very interesting facts which are con- 
nected with it, and also in an especial manner with the particular phenomena 
we are considering. 
Experiments.—Two pieces of camphor swung in air in close contiguity, 
at the ends of very fine and long threads, do not manifest any repellent effect 
in regard to each other, while, if placed upon water, though at first there is 
an appearance of a mutually repellent force in action, there is, after a short 
time has elapsed, an appearance of a mutually attractive force—they actually, 
as you see, move toward each other and close together. Now, you will allow 
that these results are not consistent with the theory which credits vapour 
with direct repulsive effects. The case of turpentine is something similar 
to the above. It is a substance which gives off vapour more freely 
than camphor, yet when one sprinkles fine particles of cork upon it and 
applies its vapour thereto, one cannot observe that the cork is at all 
affected thereby. But not only this, one can get the very reverse of 
repulsion during the emission of vapour; thus, upon either turpentine or 
kerosene a small piece of cork is placed, and a rod moistened with ammonia 
is then brought to within about half an inch of it, when the cork may 
be observed to positively rush to the rod and follow it about as obediently 
as a needle can respond to the movements of a magnet.* 
Taken as a whole, the results which I have just described or exhibited 
to you, do, as I conceive, indisputably show that this recession of particles 
under the influence of camphor is, appearances notwithstanding, not due to 
the direct impingement of vapour on them, but rather to some effect follow- 
ing thereupon ; and it seems therefore necessarily to follow that the move- 
ments of this substance (camphor) on water, are also not the direct result of 
impingement, but the result of something which follows it. 
And now, with the popular theory thus disproved before you, it may 
occur to some one here, as it did to me, that possibly these movements of 
* Volatile acids, also water, applied in this way have the reverse effect, while tur- 
pentine is neutral. The rod alone, if warm, has also an apparent repulsive effect on 
the cork, 
