376 On Dalton’s Theory of Chemical Composition. [Noy. 
arrangement of 28 atoms of carbon combined with 35 of oxygen, 
we find it very confused; and hence we may reasonably doubt 
whether nature ever forms such combinations. Upon Mr. Dalton’s 
supposition, however, the reason for the agreements, which he has 
pointed out, is obvious. It should be observed; that the agreement 
in the first stated combination of three elements, in three different 
compounds, is quite of a different kind from that of the combina- 
tion of multiples of the same elements. If no two combinations of 
the same elements had ever been found, the combination of three 
elements, as observed in the first three compounds, might still have 
existed ; and Mr. Dalton’s explanation appears to be the only one to 
which such phenomena can be referred. Respecting the fourth and 
fifth compounds, it may be questioned whether the relative weight 
of an atom of. carbon may not be 2°& instead of 5-6, and one atom 
of carbon be anited to one of hydrogen in the composition of car- 
bureted hydrogen, and one atom of carbon to one of oxygen in car 
bonic acid. Upon this supposition, then, we must have two atoms 
of carbon united to one of hydrogen in olefiant gas, and two atoms 
of carbon to.one of oxygen in carbonic oxide. 
To this arrangement Mr. Dalton offers the following objections : 
1. It is almost universally observed in chemical compounds, that 
the most simple are the most difficult to be decomposed ; and car- 
bonic oxide being much: more difficult to be decomposed than car- 
bonic acid, we cannot consistently suppose the latter to be ihe most 
simple in its composition. If we attend to the probable mechanical 
actions of the elementary atoms on each other, we may receive 
additional confirmation of this principle of composition. In the 
compression of elastic fluids, it is found that their expansive force 
is nearly in proportion to their density; and Sir Isaac Newton has 
demonstrated (Principia, lib. 2, prop. 23,) that if such fluids are 
composed of particles mutually repelling each other, the central 
distances of the. particles are reciprocally as the cube roots of the 
densities of the fluids, and the repelling forces of the particles are 
reciprocally as their central distances. If we suppose this law of 
repulsion to continue the same after chemical union as before, the 
union of two or more particles of atoms of one element to one atom 
of another, cannot be so strong as when they are united one to one. 
For if H H be two atoms of hydrogen 
attracted by C, an atom of carbon ; 
KR 
and if H and H mutually repel each e 4 TR : 
other, they will assume positions dia-  ; 
metrically opposite to each other, and i, / 
their attraction to C will be diminished — : 
by their mutual repulsion. Now ifwe  : 7) 
suppose A, B,D, to be three atoms of i 77 
hydrogen united to C, they will 
assume positions at equal distances from each other round C. Draw 
the diameter D E, join C A, E A, and A D, and draw C F  per- 
pendicular to AD. The repulsion of A from D will be greater 
. 
