C H E M 
Lime-water forms a precipitate with broth j it is cal¬ 
careous' phofphat. Cauftic alkalis and urine have the 
fame effefil. Mufcles diddled in cauftic alkali become 
red, though previous wafliing had rendered them white. 
With nitric acid, azotic gas is obtained. 
Berthollet has lately difeovered a new acid by the dis¬ 
tillation of mufcular flefti. The liquid procured by dif- 
tillation from animal fubftances had appeared hitherto to 
contain only carbonat. of ammoniac and an oil; but this 
chemill found in it an acid, to which he has given the 
name of the zoonicacid. He obferved this acid in the li¬ 
quid obtained from the gluten of wheat, the yeaft of 
beer, bones, and woollen rags, diftilled for the prepara¬ 
tion of themuriatof ammoniac. He therefore considers 
it as produced by the dillillation of all animal fubftances. 
To feparate this acid, mix quicklime with the diftilled 
liquid, after having feparated the oil, and then boil or 
diftil the mixture. Carbonat of ammoniac is exhaled; 
and when the odour ceafes to be fiiarp, filter, and add a 
little quicklime to the liquid, which boil again, till the 
fmell of the ammoniac goes off entirely. What remains 
is zoonat of lime, which filter again ; then pour on wa¬ 
ter impregnated with carbonic acid, or blow into the li¬ 
quid through a tube, in order to precipitate, by the car¬ 
bonic acid of the refpired air, the quicklime which may 
be held in folution without being combined. Zoonat 
of lime may therefore be employed to effefit combinations 
by complex affinities; but, to obtain the zoonic acid 
pure, make ufe of the following procefs: Mix the folution 
of zoonat of lime in water, made pretty ftrong (rap- 
procliee) in a tubulated retort with the phofphoric acid; 
then diftil it. The dillillation, as the zoonic acid has 
very little volatility, requires a degree of heat nearly 
equal to that of boiling water. The liquor mull then be 
made to boil. If two veffels be adapted, one after the 
other, nothing will pals into the fecond. It appears that 
a part of the acid is deftroyed by the afition of the heat; 
for the liquid which is in ebullition becomes brown, and 
grows black at the end of the operation. It may thence 
be concluded that this acid contains carbon. 
The zoonic acid has an odour like that of meat when 
frying, and is indeed formed during that procefs. It has 
an auftere tafte. It gives a ftrong red colour to paper 
tinged with turnfol, and produces an effervefcence with 
alkaline carbonats. It did not appear to produce with 
alkaline and earthy bafes falls which cryftallize. It forms 
a white precipitate in a folution of acetit of mercury in 
water, and in that of the nitrat of lead; fo that it has 
more affinity with the oxyd of mercury than the acetous 
acid, and with the oxyd of lead than the nitric acid. It 
aids on the nitrat of filver only by complex affinity ; and 
the precipitate if then forms grows brown with time, 
which Ihewsthat this precipitate contains hydrogen. The 
zoonat of potalh calcined, did not form Pruffiat of iron, 
with a folution cf that metal. 
Of the hard or solid Parts. 
The hair, the nails, the ftiells, and the cartilages, hold 
a middle place between the foft parts and the hard. The 
hard parts, properly fo called, are the bones. 
The hair is a fort of emunftory ; its change of colour, 
and its lenfibility, are proofs of this fa£t; it is known 
that in certain dil'eafes it is dangerous to cut the hair. 
Black hair is moft loaded with carbonat of lime; it is 
harder, and more fubjeft to turn grey, than lighter hair. 
There are inftances of fudden fright turning the hair 
grey in one night’s time. Hair, in dillillation with a 
naked fire, gives out carbonat of ammoniac, a concrete 
oil, a coal relembling carbure of iron, and lome Pruffic 
acid; by the aftion of cauftic alkalis; carbonated hydro¬ 
gen gas and calcareous phofphat. Oxygenated muriatic 
acid whitens hair. Nitric acid turns it yellow. The mu¬ 
riatic acid will diffolve it by the affiftance of heat, which 
the acetous acid does not; but which alkalis do com¬ 
pletely. If an acid be poured into the folution, there is 
I S T R Y. 3 7 ir 
a precipitate; fulphurnted hydrogen gas it difengaged if 
mmiatic acid be ufed, azotic gas if nitric acid. 
Hair undergoes little change by the aftion of boiling 
water ; a little gelatin is obtained at laft. Hair has been 
regarded as unchangeable ; it exifts when all the other 
arts are corrupted and deftroyed. Hair may therefore 
e regarded as the moft durable part of the body; a fa£l 
which has been frequently evinced by the accidental dig¬ 
ging up of human fculls, on which the hair has been 
found in a ftate of life and growth. 
To turn red or light hair black, rub it with an acetous 
folution of lead, or oxyd of lead, the nitric folution of 
filver, or even of mercury : having foaked the hair, put 
a little oil to it, which makes it blacker. All thefe ope¬ 
rations help to burn up or deftroy the hair; and it is not 
uncommon to fee the head break out in tumours, and 
the falivary glands affedled, in perfons who thus take 
meafures to change the natural colour of their hair. 
Feathers, by fire and re-agents, give nearly the fame 
produbls as hair. Weakened muriatic acid poured over 
feathers, makes a black precipitate; the nitric acid only 
changes them of a yellow colour. Feathers are rather 
lefs foluble in potafh than hair; they alfo afford lefs am- 
moniacal carbonat. 
BriJJles have properties fomewhat fimilar. By diftilla- 
tion in a retort, they give out carbonat of ammoniac 
and phofphat of lime. White bridles are turned yellow 
by ftrong nitric acid. Alkalis do not form a fimple com¬ 
bination : ammoniac is difengaged, and Pruffic acid, 
which would form a very goodPruffian blue with fulphat 
of iron. They form very good foaps alfo. 
Of Cartilages.— Thefe may be regarded as the be¬ 
ginning of bones ; and tendons, may be confidered nearly 
in the fame light. In boiling water, they melt into a ge¬ 
latinous matter; they differ from bones only in the greater 
or lefs quantity of phofphat of lime which they contain. 
See Anatomy, vol. i. p. 526-581. 
Of Horn.— The (havings cf horn, by long boiling in 
water, may be converted into a jelly ; in this manner 
hartfhorn is prepared for pharmaceutical purpofes. Take 
one part of hartftiorn (havings, and fix parts of water; 
put them into a tin-kettle, made to (hut 1b clofe that 
there may be very little if any evaporation. Boil the 
mixture over a (low fire for twelve hours : drain the de- 
coftion, while warm, through a hair-fieve. In making- 
up this jelly for fick perfons, add one half-part of white 
wine and one part of fugar ; clarify with the white of an 
egg. When the liquor is quite tranfparent, pour it boil¬ 
ing hot through the (litre, upon which is to be previoufiy 
put thirty grains of cinamon in grofs powder, and 180 
grains of fpirit of lemon. Acids promote the folution 
of horn in water, and contribute to its clarification. 
Of Bones.— Bonesarenot entirely an earthy fubftance, 
as was formerly fuppoled, but a combination of phofpho¬ 
ric acid and lime. Bones in their origin are membranous; 
they are much fofter in children than in adults, and in 
old people are very brittle ; hence it is much more diffi¬ 
cult to make them knit and grow together after they 
have been broken ; and in very old people they never will 
become firm after fucli accidents. 
Bones expofed to the air become covered with a yellow 
undluous matter. With a gentle fire, they grow black 
within, white wilhout. Diftilled in a retort, they afford 
a great quantity of fat oil, an ammoniacal liquor, and 
carbonat of ammoniac ; carbonated hydrogen gas is dif¬ 
engaged alfo. The coal is of difficult incineration; it 
leaves a wffiite refidue, which, by waffling in cold water, 
furniffies a little carbonat of foda; hot water then lepa- 
rates a certain quantity of fulphat of lime, and fome cal¬ 
careous phofphat remains. The animal oil which is ob¬ 
tained, when diftilled afrefli by a gentle heat, is known 
by the name of Dippel's animal oil. 
By continuing the calcination, the coal is burnt; all 
the gelatinous matter is confumed, nothing remains 
but the calcareous phofphat, which is friable. If the heat 
be 
