326 C II E M 
the products run together into a large receiver; then 
boil 'them in water, by which means a large quantity of 
the acid is obtained. 
Deyeux has another procefs, as follows : Into a veffel 
of giazed earth, prof done, put four parts of benjamin 
in grots powder, and add eight parts of water: boil the 
mixture gently for a quarter of an hour, din ing it from 
time to time with a wooden fpatula; drain the liquor, 
boiling as it is, into another earthen veil’d placed on a 
fand-bath. The liquor paffes over very clear, and pre- 
ferves its.tranfparency while hot; but as it cools it grows 
turbid,' and depofits’ regular crydals white and lhining. 
Draw' off the nntant liquor, and evaporate with a gentle 
heat; more crydals are obtained by cooling. The boil¬ 
ing. may be repeated feveral times, fo as to exhaud the 
benjamin entirely of its acid. 
Fourcroy advifes the benzoic acid, for the ufe of per¬ 
fumers, to be drawn from the urine of horfes and cows ; 
nothing more is necellary than to pour fulphuric acid 
over the water preffed from the litter and dung of thefe 
animals; fince much calcareous benzoat is contained 
therein, benzoic acid will be thus obtained. 
The pure benzoic acid has a (lightly lour, penetrating, 
hot, and acrid, tade ; its fmell is but dightly aromatic, 
and it reddens the colour of turnfole very well. 
Heat volatilizes it,, and at the lame time Angularly in- 
creafes its odour. If it be expofed to the aftion of the 
blow-pipe in a filver fpoon, it liquifies, according to the 
obfervation of Lichtendein, and evaporates without in¬ 
flaming. If it be differed to cool, it forms a folid crud, 
whole lurface prefents traces of cryftallization in diver¬ 
gent rays : it does not burn with flame, unlefs it be in 
coiltaft with bodies which are themfeives drongiy in¬ 
flamed; the contadt of a burning coal only caules it to 
fublime rapidly. Air does not appear to have any ac¬ 
tion upon ‘this acid ; for, after having been preferred 
twenty \ ears in a glafs veffel, it was very pure, and had 
lod nothing of its weight: its fmell is dillipated, but it 
recovers it again by heat. The benzoic acid is but fpa- 
ringly foluble in cold water: from the experiments of 
Wenzel and Lichtendein, it appears that 400 grains of 
cold water diffolve no more than one grain, and that the 
fame quantity of boiling water can diffolve twenty grains, 
of which nineteen feparate by cooling. 
The benzoic acid unites to all the earthy and alkaline 
bafes, and forms with them the benzoats ofalumine, of 
barytes, of magnefia, of lime, of potalh, of foda, and of 
ammoniac; the charafleridic properties of thefe feveral 
combinations are not known, nor the various attractions 
of this acid for the bafes. Lichtenffein affirms that it 
prefers the fixed alkalis, and even ammoniac, to the 
aluminous, magnefian, and calcareous, earths : but more 
numerous experiments are required to determine exaftly 
the order of thefe attractions, more efpecially as Berg¬ 
man arranges them differently : according to him, lime 
leparates the alkaline bafes, and barytes leparates lime : 
it difengages the carbonic acid from all thefe bafes. 
The concentrated fulphuric acid readily diifolves it 
without heat, and without noile, according to the fame 
chemift; neverthelefs it paffes to the Hate of fulphu- 
reous acid. The benzoic acid may be feparated with¬ 
out alteration by water. 
The nitric acid diifolves it in the fame manner, and 
water eoually difengages this fait unaltered. Morveau 
augmented the aCtion of thefe two bodies by heat; the 
nitrous gas was not difengaged but towards the end : 
and the benzoic acid was fublimed entire and without al¬ 
teration. How'ever, Hermftadt affirms, that, by employ¬ 
ing the concentrated nitrous acid, the benzoic acid be¬ 
comes fluid, more fixed, and aflumes the characters of 
the tartareous or oxalic acid; but this refult, which is 
irfelfvery uncertain, requires additional-refearches. That 
which appears to be the moft certain refpeCting this 
acid is, that it differs by its nature and properties from 
2 
S T R Y. 
all the other vegetable -acids, and that it retains an effen- 
. tial oil, which gives it fmell, volatility, combuffibility, 
and folubiiity in alcohol. 
With muriatic acid, the benzoic acid may be feparated 
from the calcareous benzoat. Alcohol diffolves it en¬ 
tirely, and it may be precipitated from that l’olution b'y 
diffiiled water. 
TARTAREOUS ACIDULE, or TARTAR. 
Acids of the fecond genus are likewife found in vege¬ 
tables in the acid ffate; but they are partly faturated 
with potalh ; and hence they are called acidules , or acids 
combined with a bafe. 
There are two fpecies. The firft is the tartareous aci- 
dule, or tartar; the fecond, the oxalic-acidule of pot alii, 
or acid of forrel. Tartar is either white or red ; both 
are found on the fides of wine-calks : it is certain that 
this tartar muff have been held in folution by the wine. 
Tartar contains many foreign matters, fuch as the ni- 
trat and fulphat of potalh, colouring- parts, &c. fo that 
we are not to regard tartar as pure acidulous tartrit, or 
cream of tartar ; for this is produced by purification. At 
Venice they purify it by folution in water, and then cla¬ 
rifying the liquor with allies and whites of eggs. At 
Montpellier, they employ for the fame purpofe a white 
argillaceous earth dug at Murviel, two leagues off. Few 
vegetables contain this acidule : grapes contain more of 
it when ripe than while green ; for at that time they 
contain citric acid ; which fully proves the converfion of 
one acid into another, as daily practised by chemilts, 
Very pure tartareous acidule is cryftallized, though 
irregularly ; it has an acid talie, lefs vinous than that of 
crude tartar. On hot coals, it emits much fmoke, of a 
penetrating empyreumatic fmell, and itfelf becomes black 
and carbonaceous. If this fubffance be diltilied in an 
earthen retort, with a receiver, connefted with an in¬ 
verted vellel of water, by means of a tube, and the fire 
be gradually raifed, a phlegm, almoft colourlefs, and 
fcarcely acid, firft comes over ; next a ftronger acid, of 
a deeper colour; and afterwards an oil, which becomes 
more and more coloured, confident, and empyreumatic ; 
and Lift of all, the concrete ammoniacal carbonat, and a 
large quantity of carbonic-acid. A very abundant coal 
remains in the retort, which, lixiviated without incinera¬ 
tion, affords a large quantity of carbonat of potalh. 
The diffiiled produfts may be rectified by a gentle heat. 
In this reiStification, the phlegm paffes over nearly co¬ 
lourlefs, the oil becomes very white and volatile, the 
ammoniac partly combines with the acid, and is not ob¬ 
tained feparate and pure, but by diltilling the laft por¬ 
tions of phlegm with the addition of potalh. The pdt- 
afli contained in the coal is not produced in the opera¬ 
tion, as many chemilts have thought, who were not fuf- 
ficiently acquainted with the nature of cream of tartar, 
but is all contained originally in this fubffance. The 
re-a< 5 tion of the fixed alkali on the oil produces the am¬ 
moniac ; and the quantity of this volatile lalt may be 
increafed, by diltilling the oil obtained from the tarta¬ 
reous acidule a lecond time with the coal it leaves in 
the retort. It appears that this formation of ammoniac 
is owing to the azot of the potalh, which unites to the 
difengaged hydrogen of the oil. 
Tartareous acidule is not altered by expofure to 
air. It diifolves in fixty parts of cold and twenty-eight 
parts of boiling water, and cryftallizes confuledly by 
cooling, as we have obferved. A certain quantity of 
earth leparates from the folution of this fait, which 
is doubtlels that which was ulcd in its purification : 
the folution reddens tincture of turnlole, and has an 
acid talte. If it be left expofed to the air, it be¬ 
comes turbid, and after lome time depofites mucila¬ 
ginous flocks. The acid is decompofed, and the fluid 
is found to contain nothing but carbonat of potalh. 
