131 
(lo the Editor of the QuarTerty Journat or Science, §¢.] 
Manchester, March 1, 1824, 
Sir, 
Tur review of the 9th editionof my Elements of Chemistry, in the last 
number of your Journal, contains some animadversions, to which I trust you 
will dome the justice to insert a brief reply. It is not, indeed, my intention 
to follow the reviewer through the variety of topics which he has introduced, 
but to confine myself to a few of those, on which I am most desirous to be 
set right with your readers, and which involve questions of some importance 
. to chemical philosophy. 
It has happened unfortunately that a passage, expressing doubts of the 
correctness of the theory of volumes, which certainly ought to have been 
expunged from the present edition of my work, was overlooked, owing to 
one or two of the early sheets having been revised under circumstances dis- 
advantageous to correctness. For this oversight, I am content to take 
upon myself whatever blame it may justly deserve ; and I should have had 
no reason to complain, had the reviewer pointed out the striking inconsis- 
tency’of the passage, which he has quoted, with other parts of my volumes. 
At page 299, vol.i., for example, I state, “analogy is certainly in favour of this 
opinion, for the instances are numerous in which gaseous bodies observe the 
law respecting volumes deduced by Gay-Lussac, and we have not at pre- 
sent any well-ascertained exception to it.” The tenor of the whole work, 
also, is inconsistent with the rejection of the theory of volumes imputed to 
me ewe reviewer ; for almost every chapter affords examples of com- 
pounds constituted in conformity to the law ; and at the close of the second 
volume I have inserted, for the first time, a table exhibiting a general view 
of such compounds. 
_ The reviewer complains (p. 338,) that I have not given a more elaborate 
and consistent account of the atomic theory, though he represents it (p. 339) 
as requiring “ mystifications,” and particularly marks the distinction 
between the atomic hypothesis and the theory of volumes. To a certain 
extent, the law of volumes is, I admit, the expression of a general fact, of 
which we have the indubitable testimony of our senses. But with regard to 
certain elementary substances, which are not known to us separately in a 
gaseous state, it is entirely matter of inference that their vapow’s unite in 
olumes, which are either equal, or multiples or sub-multiples of each other. 
We have, for example, no argument but from analogy, that this holds with 
respect to carbon; nor, if we admit the probability of such combinations, 
have we any decisive proof that the volumes, which have been assigned, are 
actually the true ones. In all such cases, where we have not access to the 
faets by direct experiment, the law of volumes rests on the ground of ana 
logy only ; and is so far purely theoretical. ‘The law, also, however, well 
established with respect to gaseous bodies, is limited to them only ; and we 
must seek for some other principle, to explain the far greater number of 
chemical combinations which take place between bodies existing under 
other forms. 
_ In the investigations which have led Mr. Dalton to the atomic system, 
it appears to me that he has pursued no other method of reasoning than 
that which has been followed by the most successful cultivators of natural 
science, siuce the introduction of K 2 inductive logic, The theory of 
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