of an
eclipse; but his prevision, though certain, is rude and indefinite:
though he can foretell the kind of effect which will follow the given
mechanical impulse, yet the quantity of effect--the height to which the
stone will ascend, and the rapidity with which it will fall--is
something utterly beyond his ken. The servant-girl has no need of
chemistry to teach her, that, when the match is applied, the fire will
burn and smoke ascend the chimney; but she is far from being able to
predict the proportional weights of oxygen and carbon which will unite,
the volume of the gases which are to be given off, or the intensity of
the radiation which is to warm the room: her prevision is qualitative,
not quantitative, in its character. But when Galileo discovers the
increment of the velocity of falling bodies, and when Dalton and De
Morveau discover the exact proportions in which chemical union takes
place, it is evident that knowledge has advanced from a rudely
qualitative to an accurately quantitative stage; and it does not admit
of dispute that the progress of science is thus a progress from the
indefinite to the definite.

From the point of view here taken it would appear that during the
present century no science has made such rapid and unprecedented strides
as Chemistry; and its progress becomes all the more striking, when we
consider the state of the science previous to the French Revolution. For
centuries nothing had been done in it whatever. Besides the commonest
previsions of every-day life, the ancients knew scarcely anything either
of chemistry or physics, except that amber possessed attractive
properties. The discovery of the strong acids by the Arabs Giafar and
Rhazes, and of phosphorus by Bechil, are almost the only landmarks in
the history of the science, until the discovery of oxygen and the
destruction of the phlogistic theory by Priestley and Lavoisier,
together with the introduction of the balance and the thermometer into
the laboratory, rendered quantitative experiments possible. Since then
its progress has been unexampled. The law of definite proportions, not
long since disputed or unwillingly accepted, has been proved to hold
even among organic compounds. A nomenclature has been invented and
perfected, such as no other science can boast of, whether we consider
the extent to which it facilitates practical operations, or its logical
value as a means of mental discipline. Chemistry has also interacted
with t