0"T' LAERT> "! - USP

344
RECENT TIMES.
means of chemical reactions. This intro-chemical bent was
sometimes carried too far, for under its influence mpn im- j
posed upon themselves problems, the solutions of which
were not discoverable, owing to the slight development ,
reached by chemistry at that time. But these views had
this great merit, that they accustomed doctors to the thought
that they might expect but little from 'speculation, much
however, if not everything, from an examination cf facts.
Chemistry owed to the perception of this circumstance
many discoveries and an important enlargement of its sub­
ject matter.
The doctor LlBAVlUS invented the method of preparing
sulphuric acid from sulphur and saltpetre, and recognized |
that the product was identical with that formed from metallic :
sulphates or alum. He first produced the bichloride of tin -|
>;
by the distillation of bichloride of mercury (corrosive sub- J
limate) with tin, and was acquainted with the process of >
colouring the glassy flux by the addition of gold. TURQUET
DE MAYERNE taught the preparation of benzoic acid cry- |
stalsby sublimation. J. B. VAN HELMONT, also, enriched '
chemistry bv a multitude of new facts. He stated the pro-;|
position that only such metals are separated from a solution j
as were previously contained in it, giving thus the death-J
blow to the goldmaker's art. He discovered carbonic acid |
gas, and introduced into chemistry the conception of gases
as being of the nature of air, but not identical with atmos-J
pheric air. The attempt which he made to study the parts
played by soil, water, and air in the nutrition of plants I
affords clear proof of the experimental method of his inquiry. J
In the writings of GLAUBER, who furnished more accurate^
information upon sulphate of soda and numerous other salts, ;
we already find a crude, but promising, appreciation of :
chemical affinity*
A deeper foundation was here laid by ROBERT BOYLE^j
who, by his corpuscular theory, sought to explain the separation
of chemical combinations into their constituent parts
* KOPP op. cit. i, in, 114, 120 et seq., 130.