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solution, it cannot affect chemical conceptions. It would have been wiser
to abstain from offering any general explanation of the effects of heat
and light through such a supposition as that of a condensation. which
does not necessarily take place, and which is, in fact, found to be often
absent. Lavoisier hoped to attach the thermological effect to the great
law discovered by Black, of the disengagement of heat proper to the
passage of any body from one state to another more dense; but such a
connection could not be established on the ground of phenomena not
invariably present, or indisputably manifested. However, it would be
too much to expect a perfect scientific reserve in discoverers who bring
out scientific truths from a region of metaphysical fantasies. It is from
their followers that we have a right to demand it; and we are compelled
to charge upon the chemists who have been eager to substitute the electro-
chemical theory for the antiphlogistic theory, properly so called, a want
of care in constructin, explanations analogous to those which are dis-
Positive Philosophy/325
missed as insufficient. To justify this charge, we must review the proofs
of the imperfection of Lavoisier s theory, still regarding it under the
two divisions just exhibited.
Berthollet saw presently that Lavoisier s method of analysis of com-
bustion must be modified. One of the chief consequences of this analy-
sis was that every acid and every salifiable base must be a result of
combustion; that is, of the combination of any element with oxygen;
whereas, Berthollet discovered that one of the most marked of the alka-
lies, ammonia, is formed of hydrogen and azote alone, without any oxy-
gen; and soon after, he proved that sulphuretted hydrogen gas, in which
also there is no oxygen, nevertheless presents all the essential properties
of a real acid. These facts have since been confirmed in every possible
way, and especially by the electric method; and the exceptions, both as
to alkalies and acids, have become so multiplied, that the investigation
and comparison of them have given that high character of generality to
the study of alkalies and acids which belongs to it in our time.
Moreover, the primitive theory of combustion has been gradually
modified by the discovery that a rapid disengagement of heat and light
is not always an indication of a combination with oxygen. Chlorine,
sulphur, and several other bodies, even non-elementary, have been found
to occasion true combustion. And again, the phenomenon of fire is no
longer attributed exclusively to any special eombination, but, in gen-
eral, to all chemical action at once very intense and vivid.
It does not follow that because Lavoisier s discoveries have parted
with some of their character of generality, they have lost any of their
direct value: and such alteration of views as there is relates chiefly to
artificial phenomena, while the natural facts remain securely established.
Thus, though there are acids and alkalies without oxygen, it is unques-
tionable that the greater number of them, and especially the most pow-
erful, are oxygenated: and again, if oxygen be not indispensable to com-
bustion, it remains the chief agent, and especially in natural combus-
tions. In natural history, the theory is applicable, almost without re-
serve, though it is insufficient for the severe conditions of abstract sci-
ence. If the universal sovereignty of oxygen has been overthrown, it will
yet be for ever the chief cleanest of the whole chemical system.
As for the second aspect of the discovery, the explanation of fire,
it was destroyed by the first direct examination of it. No new facts were
required for its overthrow, but merely a more scientific appreciation of
common phenomena. It will not even serve naturalists for their concrete
326/Auguste Comte
purposes in any degree having never really explained the most ordinary
effects The required condensation is found to be only occasionally present
and often absent in the most important cases, so at if it were not for the
connection of this aspect of the theory with a sounder one, it would be
inconceivable hove it could have held its ground up to a recent period,
busy as the chemists were with other theoretical speculations. After find-
ing that in cases where condensation was supposed, expansion exists
instead; and that where we find vivid combustion, there should, by the
theory, be a great cooling, we are brought to the reflection that if the fire
on our hearths was not a matter of daily fact to us, its existence must
become doubtful, or be disbelieved, through those very explanations by
which the phenomenon has been proposed to be established. To my mind,
this is a clear indication that the chemical production of fire does not
admit, in a general way, of any rational explanation. Otherwise it ap-
pears incomprehensible that men of such genius and such science, at a
time so near our own, should have been so deluded. The electric fire,
now proposed for an explanation. must have been sufficiently known to
Lavoisier, Cavendish, Berthollet, and others, to have served as a basis
to their theory, if its preponderance over the merits of their hypothesis
had been so great as is now commonly supposed. This consideration
however, striking as it may be, is no dispensation from the duty of ex-
amining the electro-chemical conception, for which we have been pre-
pared by this short account of its antecedents.
According to this theory, the fire produced in the greater number of
strong chemical reactions must be attributed to a real electric discharge
which takes place at the moment of combination (by the mutual neutral-
ization, more or less complete, of the opposite electric conditions) of the
two substances under consideration, one of which must be electro-
positive and the other electro-negative. There is every reason to fear,
however, that when this theory has been effectually examined, it will be
found as defective in rationality as its predecessor. If electric effects are
concerned in all chemical phenomena, as seems to be now agreed upon
by most chemists and physicists, they must oftener be supposed than
found: and the electric symptoms are most impossible to detect in pre-
cisely those chemical phenomena which have been most relied on for
overthrowing the old theory. And in the cases in which electrization is [ Pobierz całość w formacie PDF ]