r>30 
to be understood by any but the adepts in 
their own mysteries. Their writings and 
vaunted professions gained implicit credit ; 
and the covetous were lilted with the desire of 
enriching themselves by means of discoveries 
which they pretended to communicate. 
This laid tiie unwary open to the tricks of a 
set of impostors, who oft’ red to communicate 
their secret for a suitable but large reward. 
Tims they contrived to get possession of a 
Sum of money with which they absconded or 
tired out the patience of their pupils by in- 
tolerably tedious, expensive, and ruinous pro- 
cesses. 
Chemists had for many ages hinted at the 
importance of discovering a universal re- 
medy, which should be capable of curing, 
and even of preventing all diseases ; and se- 
veral of them had asserted, that this remedy 
was to be found in the philosopher’s stone, 
which not only converted baser metals to 
gold, but possessed also the most sovereign 
virtue, was capable of curing all diseases in an 
instant, and even of prolonging life to an in- 
definite length, and of conferring on the adepts 
the gift of immortality on earth. This no- 
tion gradually gained ground ; and the 
word chemistry, in consequence, at length 
acquired a more extensive signification, and 
implied not only the art of making gold, but 
the art also of preparing tlie universal medi- 
cine. 
About the time that the first of these 
branches was sinking into discredit, the se- 
cond, and with it the study of chemistry, ac- 
quired an unparalleled degree of celebrity, 
and attracted tiie attention of all Europe. 
This was owing to the appearance of Iheo- 
phrastus Paracelsus, who was born in 1493, 
near Zurich in Switzerland ; and was, in the 
34th year of his age, after a number ot whimsi- 
cal adventures,' which had raised his reputation 
to a great height, appointed by the. magis- 
trates of Basil to deliver lectures in their 
city ; lie was the first public professor of 
chemistry in Europe. 
The character of this extraordinary man is 
universally known. i hat he was an im- 
postor, ail'd boasted of secrets which lie did 
not possess, cannot be denied ; but it must 
be acknowledged that his talents were great, 
and that his labours were not entirely useless. 
He contributed not a little to dethrone Galen 
and Avicenna, who at that time ruled over 
medicine with absolute power; and to re- 
store Hippocrates and the patient observers 
of nature to that i hair, from which they ought 
never to have been expelled. He certainly 
gave chemistry an eclat which it did not betore 
possess ; and this must have induced many of 
those laborious men who succeeded him to 
turn their attention to tiie science. Nor 
ought we to forge t that by carrying his spe- 
culations concerning the philosopher's stope, 
and the universal medicine, to the greatest 
height of absurdity, and by exemplifying 
their emptiness and inutility in his own per- 
son, he undoubtedly contributed more than 
any man to their disgrace and subsequent ba- 
nishment from the science. 
Yan Helmont, who was born in 1577, may 
be considered as the last ot the alchy mists. 
His death completed the disgrace of the uni- 
versal medicine. His contemporaries, and 
those who immediately succeeded him, at- 
tended solely to the improvement of _ che- 
mistry. The chief of them were Agricola, 
CHEMISTRY. 
Beguin, Glaser, Erkern, Glauber, Kuhckei, 
Boyle, &c. 
The foundations of the alchymistical system 
being thus shaken, the f$cts which had been 
collected soon became a heap ot rubbish, and 
chemistry was left without any fixed princi- 
ples, and destitute of an object. It was then 
that a man arose, thoroughly acquainted 
with the whole of these facts, capable ot ar- 
ranging them, and of perceiving the import- 
ant purposes to which they might be applied, 
and able to point out the. proper objects to 
which the researches of chemists ought to be 
directed. This man was Beecher. He ac- 
complished the arduous task in his work en- 
titled Physica Subterranca, published at 
Francfort in 1669. The publication ot tins 
book forms a very important sera in the his- 
tory of chemistry, it then escaped for ever 
from the trammels of alchy ray, and became 
the rudiments of the science which we find it 
at present. 
Ernest Stahl, the editor of the Physica Sub- 
terranea, adopted, soon after Beecher’s 
death, the theory of his master ; but he sim- 
plified and improved it so much, that he made 
it entirely his own; and accordingly it has 
been always distinguished by the name oi 
the Stjihlian theory. 
Ever since the days of Stahl, chemistry has 
been cultivated with ardour in Germany and. 
the North ; and the illustrious philosophers 
of these countries have contributed highly 
towards its progress and its rapid improve- 
ment. The most deservedly celebrated ot 
these are Margraf, Bergman, Scheele, Kla- 
proth, &c. 
In France, soon after the establishment ot 
the Academy of Sciences in 1666, Homberg, 
Geoffroy, and Lemery, acquired celebrity by 
their chemical experiments and discoveries ; 
and after the new-modelling of the Academy, 
chemis'ry became the peculiar object or a 
part of that illustrious body. Rouelle, who 
was made professor ot chemistry in Paris 
about the year 1745, contrived to infuse his 
own enthusiasm into the whole body ot the 
French literary men ; and troin that mo- 
ment chemistry became the fashionable stu- 
dy. Men of eminence appeared every 
where, discoveries multiplied, the spirit per- 
vaded the whole nation, extended itselt over 
Italv, and appeared even in Spain. 
After the death of Boyle, and of some 
other of the earlier members of the Royal So- 
ciety, little attention was paid to chemistry 
in Britain, except by a few individuals. The 
spirit which Newton had infused for the ma- 
thematical sciences was so great, that for many 
years they drew within their vortex almost 
every man of eminence in Britain. But when 
l)r. Cullen became professor of chemistry in 
Edinburgh in 1756, he kindled a flame of en- 
thusiasm among the students, which was 
soon spread far and wide by the subsequent 
discoveries of Black, Cavendish, and Priest- 
ley ; and meeting with the kindred fires 
which were already burning in Prance, Gei- 
many, Sweden, and Italy, the science of che- 
mist rv burst forth at once with unexampled 
lustre. (See the article Air pages 29 and 30.) 
Hence the rapid progress which it has made 
during the last forty years, the universal 
attention which it lias excited, and the unex- 
pected light which it has thrown on the arts 
land manufactures. 
As the theory now universally received 
derived, in a great degree, its origin and 
support from the discovery of the composi-. 
tion of water (Sec Air as above), we shall pro- 
ceed to state this important point of doctrine. 
Water was long considered as an elemen- 
tary principle ; no one had been able to de- 
compose if ; but since the experiments of 
Cavendish, Lavoisier, and others, its true na- 
ture has been accurately ascertained ; and 
water may now be decomposed with as much 
facility as almost any other substance with 
: which we are acquainted. M ater is com- 
posed of oxygen and hydrogen : it may, by 
undeniable experiments, be converted into 
these gases, and by the combustion of them 
hi proper proportions, a quantity of water 
will be produced equal to tiie weight of the 
gases employed : ot this we shall proceed to 
give the requisite proofs by experiments. 
Experiment!. A tube of common glass 
E F (lig. IS), well annealed, and difficult to 
be fused, about an inch in diameter, is placed 
across a furnace C F E D, in a position some- 
what inclined, and to its upper extremity is 
adapted a glass retort A, containing a known 
quantity of distilled water, and resting on a 
furnace* V X. To the lower extremity of the 
glass tube F, is applied a worm S S, con- 
nected with the double tubulated flask H ; 
and to the other tubulure is adapted a bent 
glass tube K K, destined to convey the gas 
to an apparatus proper lor determining the 
quality and quantity of it. When the w hole 
is thus arranged, a lire is to be kindled in the 
furnace C E, and maintained iir such a man- 
ner as to bring the glass tube EF to a red- 
heat, but without fusing it : at the. same time 
so much fire is to be maintained in the fur- 
nace VN, as to keep the water in the re- 
tort A in a continual state of ebullition. In 
proportion as tire water in the retort A as- 
sumes the state of vapour by ebullition, it 
fills the interior part of the tube E F, and 
expels the atmospheric air, which is evacuated 
bv the worm Sb, and the tube KK. The 
steam of the water is afterwards condensed 
by cooling in the worm S S, and falls drop 
by drop, in the state of water, into the tubu- 
lated liask II. When the whole of the water 
in the retort A is evaporated, and the liquor 
in the vessels suffered to drain off complete- 
ly, there is found in the flask H a quantity of 
water exactly equal to that which w as in the 
retort A : of course there has been no disen- 
gagement of any gas : so that this operation 
was merely a common distillation, which 
nave absolutely the same result as if the water 
had never been brought to a state of incan- 
descence in passing through the glass tube E F. 
Exp. 2. Every thing being arranged as 
in the preceding experiment, 28 grains of 
charcoal reduced to fragments, and which 
had been previously exposed for a long time 
to a white heat in dose vessels, were next 
introduced into the glass tube EF. The 
operation was then conducted as before, and 
the water in the retort A kept in a continual 
state of ebullition till it was totally evaporat- 
ed. The water in the retort A w'as distilled, 
as in the preceding experiment ; and being 
condensed in tiie worm S S, had fallen, drop 
by drop, into the flask II ; but at the same 
time there had been disengaged a consi- 
derable quantity of gas which escaped 
through the tube K K, and w'as collected in a 
proper apparatus. When the operation was 
finished, there was found nothing iu the tube 
