Encyclopaedia Britannica, or, a Dictionary of arts, sciences, and miscellaneous literature : enlarged and improved. Illustrated with nearly six hundred engravings > Volume 18, RHI-SCR

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SJieelc. jaftly entitled the author to that fame which his book
y—^ procured him. It was fpread abroad through every coun¬
try, became foon out of print, was reprinted, and tranf-
lated into many languages. The Engliih tranflation is
enriched with the notes of that accurate and truly phi-
lofophic genius Richard Kirwan, Efq.
Scheeie now diligently employed himfelf in contribu¬
ting to the Tranfaftions of the Academy at Stockholm.
He firft pointed out a new way to prepare the fait of ben¬
zoin. In the fame year he difeovered that arfenic, freed
in a particular manner from phlogifton, partakes of all
the properties of an acid, and has its peculiar affinities
to other fubftances.
In a DhTertation on Flint, Clay, and Alum, he
clearly overturned Beaume’s opinion of the identity of
the fiiiceous and argillaceous earths. He publilhed an
Analyfis of the Human Calculus. He ffiewed alfo a
mode of preparing mercurius dulcis in the humid way,
and improved the procefs of making the powder of Al-
garoth. He analyfed the mineral fubftance called
mohjbdena or flexible black lead. He difeovered a
beautiful green pigment. He ffiewed us how to de-
compofe the air of the atmofphere. He difeovered that
fome neutral falts are decompofed by lime and iron.
He decompofed plumbago, or the common black lead.
He obferved, with peculiar ingenuity, an acid in milk,
which decompofes acetated alkali *, and in his experi¬
ments on the fugar of milk, he difeovered another acid,
different in fome refpe&s from the above-mentioned
acid and the common acid of fugar. He accompliffied
the decompofidon of tungften, the component parts
of which were before unknown, and found in it a pecu¬
liar metallic acid united to lime. He publilhed an ex¬
cellent differtation on the different forts of ether. He
found out an eafy way to preferve vinegar for many
years. His invedigation of the colouring matter in
Pruffian blue, the means he employed to feparate it,
and his difeovery that alkali, fal ammoniac, and char¬
coal, mixed together, will produce it, are flrong marks
of his penetration and genius. He found out a pecu¬
liar fweet matter in expreffed oils, after they have been
boiled with litharge and water. He ffiewed how the
acid of lemons may be obtained in cryftals. He found
the white powder in rhubarb, which Model thought to
be felenite, and which amounts to one-feventh of the
weight of the root, to be calcareous earth, united to the
acid of forrel. This fuggelfed to him the examination
of the acid of forrel. He precipitated acetate of lead
With it, and decompofed the precipitate thus obtained
by the vitriolic acid, and by this procefs he obtained
the common acid of fugar ; and by {lowly dropping a
folution of fixed alkali into a folution of the acid of fu-
gar, he regenerated the acid of forrel.—-From his exa¬
mination of the acids contained in fruits and berries, he
found not one fpecies of acid alone, viz. the acid of le¬
mon, but another alfo, which he denominated the mala-
ceous or malic acid, from its being found in the grcateR
quantity in apples.
By the decompofition of Bergman’s new metal (fidc-
rite) he {hewed the truth of Meyer’s and Klaproth’s
conjefture concerning it. He boiled the calx of fiderite
with alkali of tartar, and precipitated nitrate of mer¬
cury by the middle fait which he obtained by this ope¬
ration j the calx of mercury which was precipitated
was found to be united to the acid of phofphorus ; fo
that he demonftrates that this calx was phofphorated
iron. He found alfo, that the native Pruffian blue
contained the fame acid. He difeovered by the fame
means, that the perlate acid, as it was called, was not
an acid fuigeneris, but the phofphoric united to a fmall
quantity of the mineral alkali. He fuggelled an im¬
provement in the procefs for obtaining magnefia from
Epfom fait; he advifes the adding of an equal weight
of common fait to the Epfom fait, fo that an equal
weight of Glauber’s fait may be obtained j but this will
not fucceed unlefs in the cold of winter. Thefe are the
valuable difeoveries of this great philofopher, which are
to be found in the Tranfa&ions of the Royal Society at
Stockholm. Moil of his effays have been publilhed in
French by Madame Picardet, and Monf. Morveau of
Dijon. Dr Beddoes alfo has made a very valuable pre¬
fect to his countrymen of an Engliffi tranflation of a
greater part of Scheele’s differtations, to which he has
added fome ufeful and ingenious notes. The following
difeoveries of Scheeie are not, we believe, publiflied with
the reft. He (hewed what that fubftance is, which has
been generally called ‘ the earth of the fluor fpar.’ It
is not produced unlefs the fluor acid meet with fiiice¬
ous earth. It appears from Scheele’s experiments to be
a triple fait, confifting of flint, acid of fluor, and fixed
alkali. Scheeie proved alfo, that the fluor acid may
be produced without any addition of the vitriolic or any
mineral acid : the fluor is melted with fixed alkali,
and the fluorated alkali is decompofed by acetated lead.
If the precipitate be mixed with charcoal duft, and
ex poled in a retort to a ftrong heat, the lead will be
revived, and the acid of fluor, which was united to it,
will pafs into the receiver poffeffed of all its ufual pro¬
perties. This feems to be an ingenious and unanfwer-
able proof of its exiftence.
He obferved, that no pyrophorus can be made un¬
lefs an alkali be prefect; and the reafon why it can bb
prepared from alum and coal is, that the common alum
always contains a little alkali, which is added in order
to make it cryftallize ; for if this be feparated from it,
no pyrophorus can be procured from it. His laft dif¬
fertation was his very valuable obfervations on the acid
of the gall-nut. Ehrhart, one of Seheele’smoft intimate
friends, afferts, that he was the difeoverer of both of the
acids of fugar and tartar. We are alfo indebted to him
for that mafterpiece of chemical decompofition, the re¬
paration of the acid of phofphorus from bones. This ap-
3 Y 2 pears
Scheete.
Turner, a gentleman who happily unites the {kill of the manufafturer with the knowledge of the philofophic che-
mift, has alfo the merit of this difeovery, as he obferved the fame fad, without having been indebted to Scheele’s
hint on the fubjed. Mr Turner has done more ; he has converted this difeovery to fome ufe in the arts j he pro¬
duces mineral alkali for fale, arifing from the decompofition j and from the lead which is united to the marine acid
lie forms the beautiful pigment called the patent yellow.