C H E M I 
and threw great light on the chemical procefies for pre¬ 
paring-mineral acids, &c. Some of the promoters of che¬ 
mical fcience fubfequent to Paracelfus, were not entirely- 
cleared of the ideas his ungoverned imagination gave 
birth to. Such were Caffius, known by his precipitate 
of gold; Sir Kenelm Digby, who believed in the fympa- 
thetic aftion of medicaments. Libavius, whofe name is 
affixed to a preparation of tin. Van Helmont, famous 
for his opinions in medicine, and the chemical notions 
he has propagated. And laftly, Borrichius, a Baniffi phy- 
fician and chemift, who firft difcovered and publiffied the 
method of inflaming oils by the nitrous acid, and is en¬ 
titled to the refpeft and gratitude of the world, for hav¬ 
ing bequeathed his library and chemical laboratory to the 
tile of indigent Undents of medicine. Alchemy, at that 
time, was in great danger from two celebrated men, who 
Tuccefsfully combated its tenets. The one was the fa¬ 
mous Kircher, a jefuit, to whom we are indebted for a 
grand and fublime work intituled, Mundus Subterra- 
neus; the other was the learned phyfician Conringius. 
The fifth epocha, comprehends the origin and pro- 
grefs of philofophical clremiftry from the middle of the 
leventeenth to the middle of the eighteenth century 5 for 
until this time, chemiftry had never been treated phi- 
lofophically. The chemical arts had been "defcribed, me¬ 
dical formula had been given and the nature of metals 
had been laborioufly inquired into with a view to the 
making of gold, or of the univerfal medicine, (delufive 
views which ftill miflead, the ignorant and enthufiaftic,) 
but nothing more had been done. The fa£ts afcertained 
were many, but no one had yet collected them, and, as 
the celebrated Macquer happily obferves, there were 
many branches of chemiftry in being, though the fcience 
itfelf was not yet in exiftence. Towards the middle of 
the feventeeth century, James Barnet, phyfician to the 
king of Poland, arranged the principal known fadts in a 
methodical manner, and added obfervations in his-philo¬ 
fophical chemiftry. The book of this learned man is the 
more valuable on account of his being the firft perfon who 
attempted to form a complete body of chemiftry, and 
ranked it among the fciences. Bohnius, profeflor atLeip- 
lic, likewife compofed a book of fcientific chemiftry, which 
had great fuccefs, and was for a long time the only ele¬ 
mentary book on this fubjedt. 
Joachim Beecher of Spires a man of the moft extenfive 
genius, phyfician to the eledtors of Mentz and Bavaria, 
went far beyond the two authors Lift mentioned, and 
caufed even their names to be forgotten. In his fublime 
work,, intituled, “ Phyfica Subterranea,” he united all 
the known fadts of chemiftry, and defcribed them with 
aftoniffiing fagacity. He has even pointed out by con- 
jedture, a great part of the difeoveries made to this day; 
fuch as the aeriform fubftances ; the poffibiiity of reduc¬ 
ing animal bones into a tranfparent glafs, &c. This work 
was commented on by a celebrated phyfician, whofe name 
fixes a moft brilliant epocha of chemiftry. J. Erneft Stahl, 
born with a ftrong paffion for chemiftry, undertook to 
comment and improve the dedtrine of Beecher. His at¬ 
tention was more particularly diredted to afeertain the 
exiftence of the inflammable earth, which he and his fol¬ 
lowers called phlogifton. Equal to Beecher in genius, 
but fuperior in accuracy of operation and order of re- 
fearch, he compofed a treatifd on fulphur, a work on falts, 
and another intituled Trecenta F.xperimenta, which have 
gained him immortal glory, and placed his name among ■ 
the firft of his age. Boerhaave, in the midft of number- 
lefs occupations, alfo cultivated chemiftry, and compofed 
a celebrated and truly profound work on this fcience. 
His treatifes on the four elements, and efpecially that on 
fire, are mafterpieces to which at that time it was fcarcely 
poffible to have made any addition. He was likewife the 
firft who attempted the analyfis of vegetables, and difco¬ 
vered the fpi-ritus re£tor, &c. 
The theory of Stahl was long followed by the whole 
chemical world, and received a new acceffion of ftrength 
from the difeoveries and improvements'of Dr. Prieftley in 
England; and by the two celebrated brothers MM. 
Rouelle, whole too early lofs is leverely felt by the fci¬ 
ence, and to whom chemiftry owes its origin in-France. 
The illuftrious Macquer, who will be long lamented by 
every lover of fcience, contributed in a moft eminent 
degree to the advancement of this fcience by his moft ex¬ 
cellent works, which are with the greateft juftice elleem- 
ed in every part of Europe, as the fureft guides to che¬ 
miftry. Befides the great obligations the world is under 
to him for his Elements and Chemical Diftionary, his 
own particular labours and difeoveries on arlenic, Pruf- 
fian blue, dying filk, on clays for pottery, &c. are luffici- 
ent to immortalize his name, and entitle him to the gra¬ 
titude of pofterity. 
The sixth epocha, commences with the difcoveiy 
of the pneumatic chemiftry, being that which is called 
the antiphlogiJUc , introduced by Lavoifier, and followed 
at the prefent day. Stahl, entirely bufied in demonftrat- 
ing the exifcence of phlogifton, and following it through 
all its combinations, feems to have overlooked the influ¬ 
ence of the air in the greateft part of the phenomena in 
which he attributes fo great an energy to the inflammable 
principle. Boyle and Hales had neverthelels already 
proved the great neceffity of attending to this fluid, in 
the operations of chemiftry. The former had obferved 
the difference between the chemical events that happen¬ 
ed in like circumftances in the air and in vacuo. The 
latter had obtained from a great number of bodies a fluid 
which he fuppofed to be air, but in which however lie 
had obferved leveral peculiar properties, fuch as odour, 
inflammability. &c. according to the various fubftances 
they proceeded from. He thought the air was the cement¬ 
ing principle, or caufe of folidity in bodies. DivPrieftley 
alfo, in repeating a great part of the experiments of Hales, 
difcovered many fluids, which though lie thought reiem- 
bled air, yet differ from it in all their effential properties. 
And in particular, he obtained from metallic oxyds or 
calces, a kind of air, much purer than that of the at- 
unol'phere. M. Bayen, a chemift juftly celebrated for the 
exaftnefs of his operations and experiments, examined 
the oxyds of mercury, and difcovered that they were re¬ 
ducible without phlogifton, and that during reduftioa 
they emitted an aeriform fluid in great abundance. 
The ingenious and much-lamented Lavoiiien firft proy- 
ed, by a great number of valuable experiments, that a 
portion of the air becomes combined with fuch bodies, as 
are calcined or burnt. In confequence of this, he ella- 
bliflied a fe£t or clafs of chemifts, who began to doubt 
the prefence of phlogifton, and attributed to the fixation 
of air, or its difengagement, all the phenomena that 
Stahl and Prieftly readily fuppofed to depend on the re¬ 
paration or combination of phlogifton. It muft be grant¬ 
ed, that this dodlrine has the advantage over that of Stahl 
in its proofs, being more ftrift, and is fo much the more 
feducing, as it agrees better with the accurate and rigor¬ 
ous manner of proceeding, which is at prefent adopted 
in the ftudy and cultivation of natural philofophy. This 
feemed to be the cafe in the opinion of the late M. Bu- 
quet, who, in his two or three laft courfes, appeared to 
give it a decided preference. The wifeft and doubtlefs 
the only proper condutt to be purfued on this occafion, 
is to wait till a great number of f'afts fliall have complete¬ 
ly demonftrated, that all the phenomena of chemiftry are 
explicable according to the pneumatic theory, without 
admitting phlogifton. M. Macquer, though well aware 
of the great revolution thefe new difeoveries could not 
but occafion in chemiftry, did not admit the opinion, 
that every fadfc is explicable without fupjtofing the exift¬ 
ence of an inflammable principle; and inftead of phlo- 
gifton, whole exiftence has never been fairly proved, he 
has fubftituted. light, the action and influence of which 
in chemical appearances cannot be called in queftion. 
Upon the whole, much is due to the ability and indefati¬ 
gable induftry of Lavoifier, in bringing forward the pneu¬ 
matic 
