C H E M I 
Ammoniac forms with acidule of tartar an ammonia- 
cal tartarit, which cryftallizes very well by evaporation 
and cooling. Bucquet affirms that its cryftals are rhom- 
boidal pyramids. Macquer obferved fome in thick prifms 
of four, five, or fix, tides ; others tlrickeft in the middle, 
and terminated by very acute points. The academicians 
of Dijon obtained them in oblique-angled parallelopi- 
pedons. Ammoniacal tartarit has a cool tafte, and is 
decompofed by heat : in the air it efflorefces : hot water 
dillolves it more readily than cold ; and it cryftallizes by 
cooling. Lime and fixed alkalies difengage the ammo¬ 
niac ; the contact of air, mineral acids, and metallic fo- 
lutions, decompofe it, 
TARTARF.OUS ACID. 
M. Retzius publifhed, in the Memoirs of Stockholm 
for J770, a procefs, invented by Scheele, for the extrac¬ 
tion and purification of this acid. Waflied chalk is 
thrown into a folution of two pounds of cream of tartar 
in boiling water, until there is no longer any effervefcence 
nor acid at liberty; fomewhat more than 1.4th of the 
weight of the cream of tartar is required : the precipitate 
of calcareous fait or tartarit of lime, which is formed mult 
be then collefted on the filtre, and wafhed with warm 
water; it commonly amounts to thirty-two or thirty- 
three ounces, on account of the water it retains. The 
liquor decanted from this precipitate affords, by evapo¬ 
ration, nearly the half of the weight of the tartarit of 
potafh, which has. not been decompofed : 9^ ounces of 
denfe fulphuric acid, diluted with five pounds five ounces 
of water, is poured on the calcareous fait of tartar, and 
the mixture is kft to digeft for twelve hours, being agi¬ 
tated from time to time, The liquor is then decanted 
from the fulphat of lime; and the water is evaporated, 
after having ascertained that it does not contain fulphuric 
acid. For this purpofe, a few drops of the acetit of lead, 
or fugar of lead, are added; if the precipitate which 
is formed be entirely foluble in vinegar, the lixivium 
does not contain fulphuric acid; if it is not foluble in 
this fermented acid, it contains the fulphuric acid, of 
which it may be cleared by digefting the liquor on a cer¬ 
tainquantity of calcareous tartarit. Lime may be ufed 
inftead of chalk, to obtain the tartareous acid: but, as 
this alkaline earth decompofes the tartarit of potafh con¬ 
tained in the tartareous acidule, the lixivium contains 
only alkali inftead of the tartarit of potafli, as in the 
former procefs. The ufe of quicklime in this decompo- 
fition affords a great quantity of acid, becaufe this earth 
decompofes twice its weight of tartareous acidule or 
cream of tartar. 
The pure tartareous acid obtained in the liquid ftate 
by either of the above deferibed proceffes, mult be eva¬ 
porated.to drynefs ; afterwards re-diffolved and cryftal- 
lized, either by gentle evaporation, or by cooling the 
liquor evaporated to the confidence of a fyrup, according 
to Bergman. It is obtained in the form of fmall needles 
acutely pointed, or fine prifms, whofe form is difficult 
to be determined. Bergman deferibes them as fmall di¬ 
verging leaves ; Retzius compares them to hairs entwin¬ 
ed together. They are at fir ft: very white, but thofe 
wnich are obtained towards the end are yellow. 
The cryftallized tartareous acid melts, fumes, blackens, 
and even takes fire by the contact of ignited bodies. By 
diftillation it affords, like the tartareous acidule itfelf, 
an acid phlegm, a fmall quantity of oil, and much gafe- 
ous carbonic acid, mixed with carbonated hydrogen gas. 
The charcoal which remains, contains neither acid nor 
alkali; which proves that this laft is not formed by the 
decompofition of.the tartareous acid by fire. This acid, 
though purified, is always oily. It is for this reafon that 
we dillinguifli it, in the new nomenclature, by the name 
of tartareous acid, and its falts by that of tartarits. It 
Is unalterable in the air, is much more foluble than tar¬ 
tareous acidule; its tafte is very penetrating; it reddens 
the tindlure of violets, and likewife that of turnfole ; it 
Vox., IV. No. zco. 8 
S T R Y. 329 
perfectly diffolves a him in e, and forms with it an alumi¬ 
nous tartarit, which affumes a gummy or mucilaginous 
appearance by evaporation. In combinations with mag- 
nefia, the pure tartareous acid likewife forms a kind of 
gelatinous matter inftead of cryftallizing. With lime it 
forms a fait which is fcarcely foluble. 
If a final! quantity of potafli be poured into its folu¬ 
tion, cryftals of the tartareous acidule, or cream of tartar- 
fall down. This difeovery of Scheele and Bergman 
throws the greateft light on the nature of this vegetable 
fait: there no longer remain, as Morveau obferved, any 
inquiries to be made concerning the compofition of tar¬ 
tareous acidule, it is known to be the tartarit of potafli 
with excefs of acid. If the proportion of potafli be in- 
creafed, a neutral fait is formed, which is perfeftly fatu- 
rated and foluble ; it is the tartarit of potafh or njegeta- 
table fait. 
The tartareous acid has no adftion upon platina, gold, 
and fiver; it diffolves their oxyds or calces ; it afts only 
infenfibly upon copper, lead, and tin; it diffolves their 
oxyds, and deprives that of lead of its red colour. It 
diffolves iron with a very flow effervefcence. It produces 
no alteration whatever in antimony in the metallic ftate, 
but it diffolves the vitreous oxyds of that metal very well. 
It takes lime from the nitric, muriatic, acetous, formic, 
and phofphoric, acids. It precipitates the nitric folutions 
of mercury, the muriatic folutions of lead, &c. Its at¬ 
tractions, pointed out by Bergman, are in the following 
order: Lime, barytes, magnefia, potafh, foda, ammoniac, 
alumine, the oxyds of zink, iron, manganefe, cobalt, 
nickel, lead, tin, copper, bifinuth, antimony, arfenic, 
fiver, mercury, gold, platina, water, and alcohol. 
OXALIC ACIDULE. 
This is called fait of for rel of commerce .—The acidulous 
oxalat, or oxalic acidule, exifts in all kinds of forrel, 
efpecially in that fpecies called by Linnseus oxalis acetofella. 
It is obtained by prefling the juice from the forrel, which 
is then to be filtered, diluted with water, and evaporat¬ 
ed till it becomes of the confidence of bream; then it is 
to be covered with oil to prevent fermentation, and left 
in a cellar for fix months. In this ftate it is partly fatu- 
rated by potafh ; it is therefore a triple fait. It differs 
from the tartareous acidule, becaufe it gives out a great 
deal of water, and by diftillation a little undecompofed 
acid ; it affords lefsgas, no oil, and its coal is lefs bulky; 
but it contains potafh, in the fame manner as the coal 
of the tartareous acidule. 
The oxalic acidule, unites to barytes, magnefia, foda, 
and ammoniac, and forms with them triple l'alts. Lime 
decompofes it, by feizing its whole acid, as well that 
which is at liberty, as that which is combined with pot¬ 
afh : 100 grains of chalk decompofe 137 grains of the. 
oxalic acidule. The precipitate of calcareous oxalat 
which is depofited, weighs 175'grains; the fupernatant 
liquor affords thirty-two grains of carbonat of potafh by- 
evaporation. This procefs cannot be ufed to prepare the 
pure oxalic acid in the fame manner as the tartareous 
acid is obtained in a ftate of purity, becaufe the calcare¬ 
ous oxalat cannot be decompofed by the fulphuric acid, 
as the calcareous tartarit is : on the contrary, the attrac¬ 
tion of the oxalic acid for lime is fo ftrong, that it takes 
it from all other acids; and a lure means of afeertaining 
the purity of the oxalic acidule, or fait of forrel of com¬ 
merce, confifts in pouring its folution into water, charged 
with a folution of calcareous fulphat. If this acidule 
be truly extradited from forrel, an abundant precipitate 
is afforded. Potafli remains in folution. 
OXALIC ACID. 
To prepare the oxalic acid, and deprive it of the por¬ 
tion of potafh which renders it acidulous, the following 
procefs is recommended by Scheele. The oxalic acidule, 
or fait of forrel, is faturated with ammoniac. Into the 
folution of this triple oxalat, compofed of the acid with 
4 P ammoniac 
