22 The Past and Present of Chemistry. [Jan., 
method of investigation. Chemistry had a long childhood, and the 
more mature phases of her life are compressed into a comparatively 
short and recent period. Chemistry in childhood and chemistry in 
youth are almost as two distinct individuals. Let us endeavour to 
compare the characteristics of this childhood and this youth—the 
problems of the one and the pursuits of the other—the past and 
present of chemistry. 
If we search for a connecting link between early and modern 
chemistry, we find it in a problem, the solution of which has occu- 
pied the minds of chemists in all ages. This problem, always more 
or less prominently kept in view, is the composition of the different 
substances found in nature or produced by art—the different hetero- 
geneous materials which can be extracted from, or made to combine 
and form, a homogeneous substance. 
The ancients made hardly any attempt to ascertain the chemical 
composition of substances. First, among the Greeks, and later 
among the Romans, we find sagacious observations on the diver- 
sities of bodies, but it was rather the physical than the chemical 
differences concerning which scientific observations were made. 
According to the doctrines of Aristotle, which, promulgated 2,200 
years ago, so long maintained their authority, the fundamental 
properties of everything corporeal and palpable were considered to 
be dryness or moisture (that is, solidity or liquidity), and warmth or 
coldness. ‘These are obviously physical conditions and different 
degrees of a physical property, and on the occurrence and the pro- 
portion of certain of these fundamental properties, other qualities, 
such as density or lightness, hardness or softness, were thought 
to depend. The assumption of the four elements, Earth, Water, 
Air, and Fire, offers to the mind a representation of the simulta- 
neous occurrence of these fundamental properties. To Earth, as 
the representative of all solids, were ascribed dryness and cold; to 
liquid Water, moisture and cold; to Air or vapour, moisture and 
heat; to Fire, heat and dryness. The four elements of Aristotle 
represented fundamental conditions of matter, and the properties of 
bodies were regarded as depending on the proportion in which they 
contained the elements—the producers of those qualities. The 
whole conception was formed from a physical point of view rather 
than from one having even the faintest approximation to that of 
chemistry. The elements of Aristotle, as such, were not regarded as 
contained in different substances —as combining to form them, or as 
separable from them by analysis. The assumption of their existence 
did not therefore involve even the merest rudiments of a chemical 
idea. ‘They were not regarded as different kinds of matter, but as 
different fundamental conditions which, when added to indifferent 
matter, endowed it with various properties. 
This view, that the difference of bodies depended essentially 
