LECT. vi.] HISTORY OF CHEMISTRY 107
which latter, on account of its completeness, had, at that
time, already become widely distributed.
With Gmelin, there is no strict distinction between mix-
tures and compounds, and this proves that he does not believe
in the real existence of atoms. Two substances, especially
when they possess only a weak affinity for each other, can
combine, according to him, in an infinite number of propor-
tions ; but the greater the affinity, the greater is their tendency
to combine in few proportions only.57 These proportions
then stand to each other in simple relations. " There can
therefore be assigned to every substance a certain weight in
which it combines with definite weights of other elements.
This weight is the stochiometric number, the chemical equi-
valent, the mixture-weight or atomic weight, and so on.
Compounds are composed in such proportions that one
mixture-weight of one substance is united to J, J, |-, f, f, i, ij,
2> 2Ji 3) 4) 5) 6, 7, or more mixture-weights of the other."
According to Gmelin, Gay-Lussac'slaw runs:—One measure
of an elastic fluid substance combines with i, i|, 2, 2j, 3, 3^,
and 4 measures of the other.
His table of equivalents is well known. It ran:—H= I,
O = 8, S=i6, C = 6, etc. Water was written HO, and in
formulae generally, the endeavour was made to replace by
simplicity what they had lost in conception and in purpose.
Chemistry was to become a science confined to observation—
indeed almost to description alone. Skill in manipulation
was all that was required ; speculation was banished as
dangerous.
It had come to this then .-—Inorganic chemistry, in con-
nection with physics, had not been able to maintain the
conception of the atom. It is my business to show, in the
next lectures, how it was reintroduced into the science by
means of organic chemistry.
57 Handbuch der theoretischen Chemie. Second Edition, 1821.