~ 
114 ~ Observations on the Doctrines 
fr. Higgins, in his Comparative View of the Phlogistic and Anti- 
phiogistic Theories, conceiving that bodies were composed of 
minute atoms, was led, from the well-known fact that oxygen 
and hydrogen gases united in the proportion of 1 to 2 in volume 
to form water, and as they unite in no other proportion, to con-_ 
sider them as uniting atom to atom. ‘* We must suppose,” he 
observes, ‘* that they contain an equal number of divisions, and 
that the difference of their specific gravity depends chiefly on the 
size of their ultimate particles; or we must suppose that the 
ultimate particles of light inflammable air require 2 or 3 er more 
of dephlogisticated air to saturate them.” The latter, he infers, 
is not the case, from its being impossible to form such an inter- 
mediate combination as can be effected in the union of sulphur 
and oxygen. From this also he concludes, that oxygen and hy- 
drogen © are incapable of uniting to a third particle of either of 
their constituent principles.” Sulphuric acid, according to him, 
is formed of 1 particle of sulphur and 2 of oxygen, and sulphureous 
acid by | of sulphur and 1 of oxygen. 
These speculations, owing to the imperfect state of chemical 
analysis, were overlooked and rejected by succeeding chemists, 
and little or no notice taken of them until Mr. Dalton, in a work 
displaying the vast powers of an enlightened mind, aided by iu- 
dustrious research, reproposed this doctrine, and again turned the 
attention of chemists to this important subject; and it appears 
to me, from perusing Mr. Dalton’s new System of Chemical Phi- 
losophy, that he is unacquainted with the writings of Mr. Higgins 
on this subject. The former has, in the work just mentioned, stated 
that chemical attraction is guided by determinate laws; that 
bodies uniting to each other in one proportion only, unite atom 
to atom, or those which combine in various proportions form 
binary, ternary, &c. geemnlinbions, one atom of the one element 
being united to 1, 2,3, &c. atoms of another. Examples are 
found in the union of oxygen and hydrogen, oxygen and azote, &c. 
one atom of the one uniting to one or more atoms of the other; 
according to some fixed mathematical relation, which Mr, Dalton 
apparently considers to be in arithmetical progression. In this 
view of affinity, it is of importanee to determine the number of 
elementary atoms that enter into the formation of a compound 
atom. Hence, should this supposition be found correct, the errors 
arising from chemical analysis may be regulated by the aid of 
mathematical calculation. "The two substances that have claimed 
particular attention, by which this may be accomplished, are wa- 
ter and ammonia, for the elements of these have as yet been 
found to unite in one proportion only. 
Mr. Murray, in his Chemistry, has observed, that the facility 
with which the numbers can be assumed is one of the means by 
which we may be deceived. Dr. 
