founded
supposition to another, we have at last bewildered ourselves amidst a
multitude of errors. These errors becoming prejudices, are, of course,
adopted as principles, and we thus bewilder ourselves more and more. The
method, too, by which we conduct our reasonings is as absurd; we abuse
words which we do not understand, and call this the art of reasoning.
When matters have been brought this length, when errors have been thus
accumulated, there is but one remedy by which order can be restored to
the faculty of thinking; this is, to forget all that we have learned, to
trace back our ideas to their source, to follow the train in which they
rise, and, as my Lord Bacon says, to frame the human understanding anew.

'This remedy becomes the more difficult in proportion as we think
ourselves more learned. Might it not be thought that works which
treated of the sciences with the utmost perspicuity, with great
precision and order, must be understood by every body? The fact is,
those who have never studied any thing will understand them better than
those who have studied a great deal, and especially than those who have
written a great deal.'

At the end of the fifth chapter, the Abbe de Condillac adds: 'But, after
all, the sciences have made progress, because philosophers have applied
themselves with more attention to observe, and have communicated to
their language that precision and accuracy which they have employed in
their observations: In correcting their language they reason better.'

CONTENTS.

PART FIRST.

Of the Formation and Decomposition of
Aeriform Fluids,--of the Combustion
of Simple Bodies, and the Formation
of Acids, Page 1

CHAP. I.--Of the Combinations of Caloric, and
the Formation of Elastic Aeriform Fluids or
Gasses, ibid.

CHAP. II.--General Views relative to the Formation
and Composition of our Atmosphere, 26

CHAP. III.--Analysis of Atmospheric Air, and its
Division into two Elastic Fluids; one fit for
Respiration, the other incapable of being respired, 32

CHAP. IV.--Nomenclature of the several constituent
Parts of Atmospheric Air, 48

CHAP. V.--Of the Decomposition of Oxygen
Gas by Sulphur, Phosphorus, and Charcoal, and
of the Formation of Acids in general, 5