Letter to the Editor, by Dr. Henry. 133. 
gation ; and it may be deserving of consideration, whether, in any instance, 
a deficiency of such matter can be proved, and whether, from this source, — 
any conclusive argument can be drawn in favour of ultimate atoms of matter 
in general. For since the law of definite proportions, discovered by che-’ 
mists, is the same for all kinds of matter, whether solid, fluid, or elastic, if 
it can be ascertained that any one body consists of particles no longer divi- 
sible, we can then scarcely doubt that all other bodies are similarly consti- 
tuted ; and we may, without hesitation, conclude that those equivalent quan- 
tities, which we have learned to appreciate by proportionate numbers, do 
really express the relative weights of elementary atoms, the ultimate objects 
of chemical research*.” A body so constituted (it is the scope of the — 
which has been just quoted to shew) is found in the earth's atmosphere, all 
the phenomema according with the supposition that it is ‘‘of finite extent, ’ 
limited by the weight of ultimate atoms of definite magnitude, no longer di- 
visible by repulsion of their parts.” 
But though the atomic theory, in its general outline, seems to me to rest 
sufficiently on the evidence of facts, and on legitimate reasoning, yet there 
are some positions which have arisen out of it, that may or may not be true, » 
without, in the latter case, impeaching its general correctness. Of this na- 
ture are the two cited by the reviewer, (p. 340) especially the first, viz., 
‘that an increase of the density of a gas indicates an incteased number of 
simple atoms associated in the compound atom.” ‘This principle, I am» 
ready to admit, may have been too hastily deduced ; for besides that it is at 
variance with the view which J have adopted of the nitrous compounds, it 
is inconsistent also with that which I have taken of the compounds of carbon 
and hydrogen; olefiant gas, the binary compound, being denser than light 
carburetted hydrogen, the ternary one. The other position, that ‘‘ of che- 
mical compounds the most simple, is the most difficult to be decompesed,’’, 
stands unimpeached, and is exemplified, as the reviewer himself remarks, in 
the greater difficulty of decomposing nitrous oxide than nitrous gas. To 
Mr. Dalton’s opinion of nitrous gas, which makes it the binary compound, 
its greater facility of decomposition might present a reasonable objection. 
But it is quite inconsistent with sound reasoning to frame a preposition out 
of Mr. Dalton’s views and mine, which are completely at variance as to the 
compounds of nitrogen, and to apply to that proposition the syllogistic me- 
thod of reasoning as a test of its truth. No syllogism can be so constructed 
as to involve in the same dilemma two persons, who disagree with each 
other as to the conditional proposition on which that syllogism is founded. 
Though I have adopted, as most probable, that view of the nitrous com- 
pounds which makes the elements of nitrous oxide to exist in binary and 
those of nitrous gas in ternary, atomic proportion, yetl consider the truth 
of this opinion as far from being demonstrated That the volumes of the 
elements of those two compounds are what they nave oeen represented by 
Gay-Lussac, I entertain very little doubt, not only from the evidence of 
other persons, but from methods of analysis which I have myself devised, 
and which, though not otherwise important, than as they bring out the re- 
sults by easy and summary processes, [ shall probably ere long lay before 
the public. But it must still remain a subject of inquiry, whether equal 
volumes of nitrogen and oxygen gases contain, as Mr. Dalton supposes, 
equal numbers of atoms ; or whether, as [ take to be more probable, the 
same number of atoms exists in one volume of oxygen as in two of nitrogen 
gas. 
. * Dr. Wollaston on the Finite Extent of the Atmosphere»—Phil, Trans, 1822. 
