This new work when given to the world was not merely an
epoch-making book; it was revolutionary. It not only discarded
phlogiston altogether, but set forth that metals are simple
elements, not compounds of "earth" and "phlogiston." It upheld
Cavendish's demonstration that water itself, like air, is a
compound of oxygen with another element. In short, it was
scientific chemistry, in the modern acceptance of the term.

Lavoisier's observations on combustion are at once important and
interesting: "Combustion," he says, ". . . is the decomposition
of oxygen produced by a combustible body. The oxygen which forms
the base of this gas is absorbed by and enters into combination
with the burning body, while the caloric and light are set free.
Every combustion necessarily supposes oxygenation; whereas, on
the contrary, every oxygenation does not necessarily imply
concomitant combustion; because combustion properly so called
cannot take place without disengagement of caloric and light.
Before combustion can take place, it is necessary that the base
of oxygen gas should have greater affinity to the combustible
body than it has to caloric; and this elective attraction, to use
Bergman's expression, can only take place at a certain degree of
temperature which is different for each combustible substance;
hence the necessity of giving the first motion or beginning to
every combustion by the approach of a heated body. This necessity
of heating any body we mean to burn depends upon certain
considerations which have not hitherto been attended to by any
natural philosopher, for which reason I shall enlarge a little
upon the subject in this place:

"Nature is at present in a state of equilibrium, which cannot