ns which he proposed to leave "as a kind of Hermetic legacy
to the studious disciples of that art," but of which he did not make
known the nature. His health became still worse in 1691, and his death
occurred on the 30th of December of that year, just a week after that of
the sister with whom he had lived for more than twenty years. He was
buried in the churchyard of St Martin's in the Fields, his funeral
sermon being preached by his friend Bishop Burnet.

Boyle's great merit as a scientific investigator is that he carried out
the principles which Bacon preached in the _Novum Organum_. Yet he would
not avow himself a follower of Bacon or indeed of any other teacher: on
several occasions he mentions that in order to keep his judgment as
unprepossessed as might be with any of the modern theories of
philosophy, till he was "provided of experiments" to help him judge of
them, he refrained from any study of the Atomical and the Cartesian
systems, and even of the _Novum Organum_ itself, though he admits to
"transiently consulting" them about a few particulars. Nothing was more
alien to his mental temperament than the spinning of hypotheses. He
regarded the acquisition of knowledge as an end in itself, and in
consequence he gained a wider outlook on the aims of scientific inquiry
than had been enjoyed by his predecessors for many centuries. This,
however, did not mean that he paid no attention to the practical
application of science nor that he despised knowledge which tended to
use. He himself was an alchemist; and believing the transmutation of
metals to be a possibility, he carried out experiments in the hope of
effecting it; and he was instrumental in obtaining the repeal, in 1689,
of the statute of Henry IV. against multiplying gold and silver. With
all the important work he accomplished in physics--the enunciation of
Boyle's law, the discovery of the part taken by air in the propagation
of sound, and investigations on the expansive force of freezing water,
on specific gravities and refractive powers, on crystals, on
electricity, on colour, on hydrostatics, &c.--chemistry was his peculiar
and favourite study. His first book on the subject was _The Sceptical
Chemist_, published in 1661, in which he criticized the "experiments
whereby vulgar Spagyrists are wont to endeavour to evince their Salt,
Sulphur and Mercury to be the true Principles of Things." For him
chemistry was the science of the composition of substances, not m