Fune 16, 1870 | 
NATURE 
I2I 
If any one will examine a popular chemical manual, he 
will find its pages occupied almost wholly with experi- 
mental results, connected by an imperfect and partial 
classification. Should he feel envious to know what laws 
have been acquired by the science, or how far it at pre- 
sent possesses a deductive form, the whole of the infor- 
mation he seeks is generally proffered in a few paragraphs. 
Nor can it be denied that, as a rule, the manuals have 
given a fair representation of the kind of chemistry that 
we are compelled to use for the purposes of teaching, 
But not only has this state of things been repeatedly 
predicted ; the result has also been discerned. The most 
distinguished chemists have from time to time seen the 
fundamental identity that exists between their own science 
and that of physics, and have recommended the conjoint 
study of these subjects as likely to prove of the greatest 
advantage to each, until the apparent and illusive differ- 
ence between them shall have vanished, and their sepa- 
rate efforts be blended in a single enterprise. In recent 
times, the special character formerly assigned to chemis- 
try is advocated only by the few who are content with the 
prevailing style of research. Every one will, therefore 
appreciate the eager interest that has always been shown 
in any attempt to construct a firm and logical union 
between chemistry and physics. Such an union is 
now being accomplished by the science of Thermo- 
chemistry. 
If we look back to the beginning of this century, we shall 
see how little reason we had to expect that the desired 
result would be brought about in such a manner. At 
that time, there were but few who did not regard heat as, 
in some way or other, a kind of matter, and not many 
who deemed its study of much importance. Lavoisier, 
it is true, touched the obscure topic with his restless 
fingers ; but while we cannot withhold our respect from 
the inventor of the calorimeter, few will excuse the great 
opponent of phlogiston for his theory of caloric. Thénard, 
on the other hand, was the first to show, in his classifica- 
tion of the metals, the great importance to chemistry of 
the study of temperature. His principles and the fruit of 
his teaching can easily be traced in modern chemistry. 
But it was not in the study of pure thermotics that 
thermo-chemistry took its rise. That science could not 
furnish, what the weakness of the mind invariably demands, 
a conception on which to proceed. Heat might be a 
mode of motion. But motion of what? The passage in 
which Rumford announced his discovery is sublime in its 
simplicity and unsullied by any materialistic taint. The 
popular prejudice stripped that magnificent idea of its 
regal investiture, and clothed it in the garments of a 
corpuscular theory. Dalton’s atomic doctrine, at first 
received with coldness, has long been almost universally 
accepted among chemists ; but it is only, perhaps, within 
the last decennium (for Mayer and Joule must be omitted) 
that a few prominent physicists, among whom Naumann 
himself is to be enumerated, have given in their adhesion 
to Dalton’s fundamental views, and constructed for them- 
selves a new basis on which to work. Thus, then, has 
arisen the science of thermo-chemistry ; and it is not, 
consequently, very surprising that it should teach us that 
heat is a kind of undulatory movement (Bewegungsform) 
of molecules or atoms. On the whole, we are inclined to 
regard the atomic constituent of the infant science as 
“accidental” (to borrow aterm from mineralogy) ; in any- 
thing equal to a calculus, it will prove to be an intolerable 
hindrance to perspicuity, infecting the purely inductive 
part with a host of extraneous entanglements, 
Professor Naumann is far too acute and experienced a 
reasoner not to perceive that it is precisely at this point 
that objections are most likely to be made. Accordingly 
he is careful to fortify his position by a well-digested 
chapter on the atomic theory, in which the usual argu- 
ments are advanced with much more than the usual 
thought and distinctness, It may aid the reader to form a 
judgment of how far his author has succeeded, if we notice 
one or two points in the discussion, Almost at the outset, 
we are warned that demands on the accuracy of a scientific 
theorist must not be severe or stern. “ The essential value 
of a theory does not consist so much in its fundamental 
hypotheses, but in the connecting of known facts and 
enabling us to discover new relations.” Further on 
there is sufficient confusion in the terms employed to 
mislead one into supposing that an element enters into 
combination with unaltered properties ; whereas, of course, 
it must always gain or lose by that process. The existence 
of bodies having the same per-centage composition, but 
different reactions, is adduced to prove that the matter 
in them must be divided into discrete parts in each 
case. Does it not rather prove that matter has nothing 
whatever to do with chemical properties? Again, the 
passage beginning “If we now suppose the process of 
mechanical division to be carried on continuously, a limit 
must at length appear,” &c., is as clear a case of feritio 
principit as we remember to have met with. 
The work of Professor Naumann is intended as a sort 
of summary, in a form specially designed for the student, 
of what the science of thermo-chemistry has been able to 
achieve. Theaccomplished author, who has taken a most 
important practical share in the results he describes, has 
spared no pains to perfect his labour with such an end in 
view. We need hardly say that an effort, in itself 
so desirable and meritorious, is in its result both oppor- 
tune and intelligible. We may as well, perhaps, point out 
that the chapters on Dissociation and kindred subjects 
have received, as was natural, the greatest amount of 
development. 
The progress of biology has repeatedly been opposed by 
an obstacle which, under the name of “mind,” it has 
scarcely known how to treat, but with respect to which it 
is just beginning to find its true position. In like manner, 
physical science, and chemistry particularly, has had 
to encounter a phenomenon which, under the name of 
“matter,” has continually impressed upon it the heaviest 
and most severe of theoretical burdens. It will be strange, 
indeed, if biology should steal a march on physics. 
E. J. MILLs 
OUR BOOK SHELF 
The Interior of the Earth, By H. P. Malet, F.L.C.S. 
8vo, pp. 175. (London : Hodder and Stoughton, 1870.) 
THIs is a very good example of a book which ought never 
to have been written. The author tells us in the introduc- 
tion that, in approaching the most complicated problem of 
the condition of the interior of the earth, he has “culled 
from contemporary literature such extracts as fit” his 
