364 C H E M 
{ tarts of pure fuet in a glazed pan. Let the fat cool a 
ittle, and then mix the folution of mercury with it, in 
a wooden mortar; work the mixture about till it begins 
to thicken; then pour it quickly, into a large paper 
mould ; when the ointment is cold, cut it into fquares. 
This compofition is much more confident than fuet itfelf. 
Fat is capable of diflolving certain metals. It unites 
with mercury in the well-known preparation called mer- 
curial ointment ; it is called alfo Neapolitan ointment, 
unguentum duplicatum, See. it is the unguentum hydrar- 
gyri fortius, or ftronger ointment of quickfilver, of the 
New London Pharmacopeia, and is direfted to be thus 
made: Take of purified quickfilver, two pounds; hog's 
lard, prepared, twenty-three ounces by weight; mutton 
fuet, prepared, one ounce by weight. Firll rub the quick¬ 
filver with the fuet and a little of the hog’s lard, until 
the globules difappear; then add what remains of the 
lard, and make an ointment. It is very difficult to ex- 
tinguifh the mercury entirely : rub a little of the oint¬ 
ment on the back of the hand, and through a magnifier 
obferve whether fome globules of mercury are yet vifible, 
in which cale the trituration mull be continued. 
Veau Delaunay, of Tours, has propofed a fhorter way 
of diflolving the mercury in fat: Triturate mercury with 
old olive-oil in an iron pot, with a long-handled wooden 
peftle; this peftle is directed to be more than two yards 
long, and to be confined at top with an iron ring. This 
is the mode of preparation now ufed for the military liof- 
pitals in France. But a mode Hill more expeditious and 
fimple, is to make a grey oxyd, by mixing together red 
oxyd of mercury, and metallic mercury ; by triturating 
this mixture, a grey oxyd of mercury is prefently pro¬ 
duced. This grey oxyd readily dilfolves in fat, and pro¬ 
duces an ointment fimilar to the former. 
As the procefs of combining mercury with hog’s-lard, 
is well known to be tedious, and to require a confidera- 
ble time, the following method of (hortening it, has been 
announced by Gottling, in his Tufchen-Bach fur Scbeia - 
hunftler, 1798. This procefs, fays he, may be Ipeedily 
performed, by the addition of a very fmall quantity of 
the flowers of fulphur. In a mixture of two ounces of 
liog’s-lard, and fix drachms of quickfilver, it will be 
necefiary to employ only iix grains of the flowers of ful¬ 
phur, and the procefs will be completed in a few mi¬ 
nutes. This diicovery cannot but prove of great ufe in 
pharmacy. 
Vauquelin has given a procefs for taking out of linen 
fuch fpots as are occafior.ed by preparations of mercury 
and lead. Walh the linen in a ley made of fifty parts of 
water, one of potafli, and one and a half of lime; when 
all the greafe is difl'olved by the alkali, and nothing re¬ 
mains on. the linen but the oxyd of mercury, plunge it 
into a tub containing a liquor compofed of twelve parts of 
water, and one part of oxygenated muriatic acid as ftrong 
as poifible, at the temperature of 6°. Let the linen re¬ 
main till the fpot is removed ; then walh it in fpring-w'a- 
ter, and afterwards in foap-water, to take away the 
fmell; then, to make it perfeftly white, it may be foaked 
for a few hours in water containing one thoufandth part 
of fulphuric or fulphureous acid. 
Lead, copper, and iron, are the three metals mofteafily 
altered by fat. If fat be left upon copper, the fat turns 
green, and the more fo as it becomes more fluid; hence 
the extreme danger of leaving food of a fat nature in 
vefiels of copper ; the danger of leaden veffeis is not much 
lefs, if the fat has any thing acid in it, or of earthen 
vefiels covered with giafs of lead. 
Acids do not aft upon fats as upon oils ; none of them 
take fire with the nitric acid; the fulphuric acid tuins 
them brown, the nitric yellow. Alkalis diflolve them, 
forming foaps in the fame manner as with oils. If thefe 
foaps are treated with a folution of alum, an oil is lepa- 
rated from them, according to Crell, and, by evaporation, 
febat of potafli. Sulphuric acid diftilled over this fait 
a 
I S T R Y. 
decompofes it, by which means is obtained the feba- 
cic acid. 
Guyton has a more fimple procefs for obtaining the fe- 
bacic acid :—Suet is melted, and quicklime added ; when 
the mixture is cold, it is boiled in a large quantity of 
water, which, by filtration and evaporation, affords the 
febat of lime, of a brown colour, and acrid tafie. This 
is purified by c lcination in a crucible, folution, and fil¬ 
tration ; a lufficient quantity of water, impregnated with 
carbonic acid, being added, to feparate the fuperabun- 
aant lime. The fluid being evaporated, affords a white 
fait, from which, by diftillation with the fulphuric acid, 
the febacic acid is dilengaged. To deprive this of the 
portion of fulphuric acid it may be contaminated with, 
Crell direfts it to be re-diflrilled from one-fourth of the 
febat of potafli, which muft be referved for this ufe. It 
may be afcertained that it contains no more fulphuric 
acid by the addition of the acetit of lead ; for, if the pre¬ 
cipitate be totally foluble in vinegar, it does not contain 
fulphuric acid. 
This acid is formed by heat in the butter of cocoa, 
fpermaceti, and probably in all fixed vegetable oils. The 
following are its characters: it is liquid, white, and of a 
very ftrong fmell; it emits white fumes, is decompofed 
by fire, becomes yellow, and affords carbonic acid. It 
ftrongly reddens blue colours ; unites, in all proportions, 
with water; forms a cryltallizable fait with lime ; and, 
with potafli and ioda, falts, vvl ich cryltallize in needles, 
and are fixed in the fire. It difiblves gold, when united 
with the nitric acid ; attacks mercury and filver; preci¬ 
pitates the nitrat and acetit of lead ; it decompofes tar- 
tarit of potafli by precipitating tartareous acidule, or 
cream of tartar, and likewife decompofes the alkaline 
acetits. When ftrongly heated on fulphuric lalts, it fe- 
parates the acid in the fulphureous ftate. It precjpitates 
the nitrats of mercury and of liiver; and decompofes the 
oxygenated muriat of mercury. This acid is compofed 
of hydrogen, carbon, and azot. 
Fat combines very readily with the colouring parts of 
vegetable iubrtances ; a proof of which is feen in ieveral 
pharmaceutical preparations, as the unguentum populeon , 
See. 
Thefe are the chemical properties of fat at prefent 
known •• they teach us, that this fubftance greatly relem- 
bles butter; that is to fay, it is a kind of concrete fixed 
oil, which owes its folidity to the oxygen which chemifts 
have hitherto attributed to the acid. With regard to its 
ufes in the animal economy, befides that of maintaining 
the heat of thole parts which it furrounds, and the agree¬ 
able plumpnefs and pliancy it produces, together with 
the whitenefs it communicates to the fkin ; it likewife ap¬ 
pears, according to Macquer, to be of uie in abfiorbing 
the fuper-abundant acids which may exilt in the bodies 
of living creatures ; it is, as it were, the refervoir of thofe 
falts. It is likewife known, that too great a quantity of 
acid, introduced into the body of an animal, dilfolves 
and melts the fat, doubtlefs by rendering it laponaceous, 
and confequently more foluble. The exceflive abundance, 
and more efpecially the alterations, of the fat, produce 
dangerous diforders in the animal economy,whole fymp- 
toms and eft’efts have not yet been well examined. Lorry 
has particularly attended to the nature of fat, and has 
difeovered a ftriking analogy between this fubftance and 
bile. This analogy appears indeed to be founded on the 
fat nature of bile, on the colour w’hich the fat aflumes 
in bilious difeafes, on the melting and diiappearance of 
the fat in long-continued affeftions of the liver, on the 
cruel method cf intreafing and of foftening this vilcus 
in lome birds, in melting their fat by long inaftion, com¬ 
bine 1 with a dry and long-contiaued heat, &c. 
Fat is ufed in foods, and is Tiouriftiing for fuch perfons 
as have ftrong digeftive powers. It is ufed externally in 
medicine, as a foftening remedy ; and as fuch it enters 
into the compofition of ointments and plalters. The 
marrow. 
