is the province of
geology to estimate the enormous aggregate of detritus, continents
washed away and new continents formed, and the face of the earth
remodelled and renewed.

[Sidenote: Progress of chemistry.] The artificial decomposition of water
constitutes an epoch in chemistry. The European form of this science, in
contradistinction to the Arabian, arose from the doctrine of acids and
alkalies, and their neutralization. This was about A.D. 1614. It was
perceived that the union of bodies is connected with the possession of
opposite qualities, and hence was introduced the idea of an attraction
of affinity. On this the discovery of elective attraction followed. Then
came the recognition that this attraction is connected with opposite
electrical states, chemistry and electricity approaching each other. A
train of splendid discoveries followed; metals were obtained light
enough to float on water, and even apparently to accomplish the
proverbial impossibility of setting it on fire. In the end it was shown
that the chemical force of electricity is directly proportional to its
absolute quantity. [Sidenote: Attraction. The elements.] Better views of
the nature of chemical attraction were attained, better views of the
intrinsic nature of bodies. The old idea of four elements was discarded,
as also the Saracenic doctrine of salt, sulphur, and mercury. The
elements were multiplied until at length they numbered more than sixty.
[Sidenote: Theory of phlogiston.] Alchemy merged into chemistry through
the theory of phlogiston, which accounted for the change that metals
undergo when exposed to the fire on the principle that something was
driven off from them--a something that might be restored again by the
action of combustible bodies. It is remarkable how adaptive this theory
was. It was found to include the cases of combustive operations, the
production of acids, the breathing of animals. It maintained its ground
even long after the discovery of oxygen gas, of which one of the first
names was dephlogisticated air.

But a false theory always contains within itself the germ of its own
destruction. The weak point of this was, that when a metal is burnt the
product ought to be lighter than the metal, whereas it proves heavier.
[Sidenote: Introduction of the balance into chemistry.] At length it was
detected that what the metal had gained the surrounding air had lost.
This discovery implied that the balance had been resorted to for