404 Transactions.— Chemistry. 
maintains to be explanatory of these movements, is re-stated in a controver- 
sial letter which appears in the ** London Chemical News."* This theory is 
quite antagonistic to the one I advocated in the paper of mine referred to, as 
it supposes these movements are due to a “ difference between the tension 
of water and that of the camphor solution at different points of the surface.'' 
I have also learned since the communication of this paper, that Mr. 
P. Casamajor has read one before the American Chemical Society, in 1874,1 
in which he ascribes these movements to electrical reactions, and in a letter 
of his published in the ** Chemical News," t he attempted to sustain this theory 
as against that of Professor Tomlinson. Along with this, I find that the 
subject of camphor-movement has been one of great interest to the scientific 
world since the year 1787, when Volta investigated it, followed by.Carradori, 
Dutrochet, Dr. Thos. Young, and, in 1862, by Prof. Van der Mensbrugghe. 
A knowledge of this and of the more recent opinion of the two scientists 
first named, has induced me to make further investigation respecting the 
phenomena of camphorie movements, and the direction of which has, I am 
happy to acknowledge, been given by information supplied by Mr. Casa- 
major. 
Before I give the results of this further investigation of mine, I will just 
say now what I have to say in respect to the rival theories which I have 
described to you. 
In regard, first, to that of Mr. Casamajor, I have to inform you that I 
tried to reproduce some of the results upon which this is founded, and was 
quite unsuccessful. One experiment, especially, I tried several times—that 
where vuleanite electrically excited is applied to camphor which has been 
rendered stationary upon water by a glass-rod, and I entirely failed to set 
the eamphor going. When one considers the effect which a minute portion 
of greasy matter has in arresting this kind of motion, one eannot avoid 
inking that the unrecognized interference of such matters in Mr. Casa- 
major's experiments has vitiated the value of their results and so led him 
a little astray. 
As regards Professor Tomlinson’s * tension" theory, I cannot go over 
the evidence upon which it rests, as I am unable as yet to possess myself of 
it; nor again can I examine the mode in which he makes the difference of 
tension described to result in camphor movement, as I have only a know- 
ledge of the bare assertion itself, being, as I have said, unable to obtain the 
essay referred to. 
Pending, therefore, the receipt by me of full and definite information of 
this kind, I must for the present forbear from any direct examination of the 
* Vol, XXXVI., p. 937. t * London Chemieal News," Vol. XXXVI., p. 191. 
f Vol. XXXVI., p. 285. 
