THE CONSTITUTION OF MATTER. 
473 
seems to bear upon the subject under discussion. Graphitic acid is prepared 
by the action of powerful agents of oxidation upon that variety of carbon 
only which is known as “ graphite ” or “ blacklead.’’ The combining weight 
of the carbon in this compound is reckoned as 33. Now it is curious that the 
“ atomic ” weight, calculated from the specific heat* of graphite, closely ap¬ 
proximates to this,—it is about 32. Here is a number which, if at all to be 
relied upon, is irreconcilable with the atomic hypothesis, no even number of 
atoms, each weighing 12 (or even the old number 6), would give, when united 
together, an aggregate of 32 or 33. There are indications, though not yet 
well-established, that there are differences of a similar kind in the atomic 
weight of several other elements (silicon, sulphur, phosphorus, and probably 
antimony and others) when examined under the different forms known as 
their allotropic modifications. 
5. The influence which quantityf exerts upon chemical reactions, is re¬ 
markable in almost every experiment that can be devised ; in some instances 
it amounts to a power which is capable of determining the manner of a re¬ 
action even apparently in opposition to ordinary affinities. The chlorides of 
bismuth and antimony are deliquescent bodies, very soluble in a small quan¬ 
tity of water, but decomposed by a larger quantity. The perchloride of anti¬ 
mony has the formula SbCl 5 ; by the action of a considerable quantity of 
water it gives an ojide and hydrochloric acid. 
2 SbCl 5 + 5H„0 = Sb 2 0 5 + 10 HC1. 
What we have to pay attention to in such examples is, the fact that if the 
experiment be tried with the weights represented in the symbolic equations, 
the decomposition will not be found to take place. 
For instance, if 2 SbCl 5 = 599 parts, and 5 H 2 0 = 90 parts, be mixed to¬ 
gether, the result will be a crystalline mass; and even if a further addition 
of water be made, the decomposition does not occur. A large and indefinite 
quantity of water is requisite to bring it about. Such phenomena were known 
long ago, when the atomic theory was first propounded, and were used as 
arguments against it by its opponents. One eminent chemist even thought 
it possible that quantity might compensate for feebleness of chemical attrac¬ 
tion, so that the less energetic a body was in its affinities, the smaller its 
combining weight. This view was of course not long retained as a general 
theory of chemical combination. These facts, however, offer an unsolved 
problem up to the present day ; for though I am not ignorant that explana¬ 
tions have been attempted, they do not appear to me to dispel the difficulty. 
6. Leaving now chemical considerations and passing to an entirely diffe¬ 
rent form of argument, I quote the following paragraphs, written by the late 
Mr. Faraday in 1844. Faraday, it must be remembered, was not only a 
physicist, but a chemist. 
“ The view of the atomic constitution of matter, which I think is most pre¬ 
valent is, that which considers the atom as something material, having a cer¬ 
tain volume upon which those powers were impressed at the creation, which 
have given it from that time to the present the capability of constituting when 
many atoms are congregated together into groups,—the different substances 
whose effects and properties we observe. These, though grouped and held 
together by their powers, do not touch each other, but have intervening 
space, otherwise pressure or cold could not make a body contract into a 
smaller bulk, nor heat or tension make it larger ; in liquids these atoms or 
particles are free to move about one another, and in vapours or gases they 
* See page 414. 
f Important and perhaps more conclusive experiments have been made upon gaseous mix¬ 
tures by Bunsen, and upon mixed solutions by Debus and others. 
VOL. XI. ^ I 
