64 HISTORY OF CHEMISTRY [LECT. iv.
exercised any immediate influence upon the science. This may
- also be explained by the fact that the hypothesis only led to
decisive results as to the number of atoms contained in the
molecule (and thus to the determination of the atomic weight)
in the case of gaseous substances, and was not applicable to
solids and liquids. Chemists, therefore, looked for new
generalisations, and the next impulse in this direction was
given by Wollaston.
Wollaston had carried out an investigation on the carbon-
ates,in 18o8,35 which appeared simultaneously with an examina-
tion of the oxalates by Thomson.30 It was shown in the papers
of these chemists that carbonic acid can form compounds with
one and with two parts, and oxalic acid with one, with two, and
with four parts of potash. These experiments produced a
great impression, because at that time there were few facts of
this kind known which had been minutely examined ; on this
account, they formed an important support to the law of
multiple proportions. But if Wollaston, on the one hand, thus
exerted an influence upon the rapid recognition which the
atomic theory met with, and consequently came to be regarded
even by authorities as an adherent of the theory,87 still, by a
later paper,88 he contributed to the abandonment of the atom
by a section of chemists, as too indefinite a basis for chemical
considerations.
In 1814, Wollaston, not without justice,represents to Dalton
how uncertain and arbitrary is his estimation of the number of
atoms in a compound; and how, in consequence, the atomic
weights are wholly hypotheticalnumbers,so that,in his opinion,
they should not be adopted. He advised, instead of the con-
ception of the atom, the introduction of the equivalent, which
word he employs for the first time. Wollaston was well
acquainted with Richter's works,80 and he derives the concep-
tion of the equivalent principally from his investigations. I
36 Phil. Trans. 1808, 96; A.C.R. 2, 34. « Phil. Trans. 1808, 63 j
A.C.R. 2, 41. *i Kopp, Geschichte. 2, 373. M Phil. Trans. 1814,
I ; Ann. Chira. 90, 138. ™ Even Wollaston remarks (he. cit.} that
Wenzel's analyses do not agree with the law of neutrality.