710 
THE CONSTITUTION OF BODY, ETC. 
the reagent e, the result being a certain precipitate, he would regard e as the 
cause of this precipitation. Next, let a, c, d , e, be the conditions required, and 
all duly present, but let b, which represents the proper temperature, be wanting, 
then add b, and the same precipitation follows. In this second case, he would 
consider b as the cause. In other words, there could be, according to this view, 
two (or more) diverse causes of one and the same result. I say result, rather 
than effect, because the former term indicates sequence only, without any re¬ 
ference to causality ; and in the illustration adduced, the totality of the condi¬ 
tions constitutes a set of co-causes, all contributing to, and converging upon 
one end, but no single one of which can properly be termed the cause. Whereas 
the cause to which I referred, and to which the co-relative term effect is the 
appropriate pendant, is the efficient cause ( causa causativa). But any present 
reference to this cause would touch upon the great problem, which I have else¬ 
where styled (a-), towards which all my utterances on these topics, whether 
moving upon it in direct lines, or revolving about it in orbits nearer or more 
remote, ultimately gravitate. 
5. I am afraid that I must have failed to express my meaning clearly re¬ 
specting the case of the presumed graphitic acid, and being but a laic in the 
science, I argue with diffidence any technical point with one of the clerus. Still, 
I must confess that I have not yet succeeded in appreciating the force of Mr. 
Tilden’s objections. Assuming that there is such a body, whose correct formula 
is C u H 4 0 5 , I ask, why should not this formula be as acceptable as such an one 
as A 12 B 4 C 6 ? The reply will probably be, because it violates the law of multi¬ 
ple proportions. To which I answer, that it may possibly be legalized by a 
clause of that very law, enacting and dealing with compound ratios. And if I 
rightly understand the nature of the objection taken, it is upon this point that 
issue is joined. Or am I to understand that the objection to this view would 
be, that the combining weight of the carbon comes out proportionally as 33 
(C 2 |), instead of absolutely as 132 (C n )? 
6. In discussing Faraday’s argument, I did not lay down anything whatever ; 
it was sufficient for my purpose to refute his reasoning. The expression 
u atmosphere ” was used in lieu of Faraday’s u space,” to denote the entire cir¬ 
cumambient space pertaining to each several atom. But are we to understand 
Mr. Tildeu as seriously admitting the possibility of empty space,—of a real 
vacuum? that there can be the room which something takes up, and yet nothing 
to take up that room ? 
7. In putting the question, “ When a measure of air is condensed into one- 
tenth of its former bulk, what has become of the other nine volumes ?” I 
think I am not too bold in saying that I have proposed a crucial problem, upon 
the solution, or the approximate solution, of which depends the next great step 
in advance of physics. I proportionately regret, therefore, that having ad¬ 
verted to it at all, Mr. Tilden has passed it over so slightly. But he will for¬ 
give me if I cannot consider him in earnest, when he speaks of heat as having 
constituted a portion of the missing nine volumes ; that very heat which he 
himself defines as being a certain kind of movement, i. e. as being not a thing 
but a fact; heat, which is a certain condition of substance, but not itself sub¬ 
stantial, filling space !* 
8. I should regret to have dealt unfairly by a writer who himself deals so 
fairly with his subjects ; but I really cannot see that I have exceeded the limits 
* Popularly speaking, lieat is said to Jill space ; meaning no more than that it is diffused 
through it. We must remember that to Jill is a verb causative, signifying to make to be full, 
and whatever makes or causes space to be full, must possess the property of extension, or, in 
other words, must distend space. Everything material subsists in space, and is acted upon 
in time ; while forces exist in time , but act in space; a distinction which, as yet, is scarcely 
recognized. Substance, therefore, has ea-tension (in space); force has in- tension (in time). 
