CHEMISTRY. 
358 
the fame time to the furface, proceeding from a portion 
of diifolved albumen ; the clot then aifumes a brown co¬ 
lour, and firmer confidence. Put in digeftion with alco¬ 
hol, it becomes harder alio ; but the ferolityi which is fe- 
parated no longer contains albumen. The alcohol ac¬ 
quires merely a lemon colour, provided it be perfeftly 
dephlegmated: mixture with water takes nothing from 
its tranfparency. Water mixed with clot of blood di¬ 
vides it, becomes red, and remains clear forfeveral days; 
it becomes turbid by degrees, and exhibits membranous 
pellicles. 
Acids aft in various ways upon clot of blood; but 
they all tend to make it more concrete, becaufe they co¬ 
agulate the albumen ftill contained in the ferum which 
adheres. The nitric acid, however, mult be excepted, 
which feems to difl'olve it; the phofphoric and fulphuric 
acids change it to a black colour. After having been 
mixed with acids, it is not fo foluble in water as before; 
it undergoes divifion only, and makes the water thick. 
Clot of blood is diifolved by the carbonats of potalli 
and ammoniac; and, when deprived of their carbonic 
acid, they become of a dark red colour. This kind of 
folution may be preferred a long time without alteration ; 
but the membranous pellicles before mentioned can no 
longer be feparated; it feems as if the alkalis, by com¬ 
bining with them, had given them a degree of folubilityr 
Clot of blood, by diftillation in a retort, affords the fame 
produfts as animal fubllances ; and the coal which re¬ 
mains contains iron, fixed alkali, &c. 
Colouring Part of Blood. —The colouring part 
prefents different phenomena from either the albumen, 
or the fibrin. It is of importance to know why the co¬ 
louring matter rather unites with the fibrin than with 
the ferum ; it is becaufe this is what firft tends to coagu¬ 
late when at reft, and the oxygen fixes with this, rather 
than with the ferum, from which it ealily feparates. The 
colouring part feems to be the richeft in the conftitution 
of the blood ; and it exhibits various phenomena, in its 
circulation in different regions of the body. Expofed to 
the contaft of air, the colouring matter abforbs oxygen, 
carbon, and hydrogen. It becomes brown from the ac¬ 
tion of hydrogen gas: With carbonic acid gas, in a well- 
corked bottle, the liquor becomes of a very dark blue; 
with oxygen gas, it takes immediately a beautiful red 
purple. If the clot of blood be put in contaft with oxy¬ 
gen gas, the latter is abforbed, and carbonic acid is 
formed. This experiment is eafily made, by mixing 
oxyd of mercury with colouring matter: the mercury 
palfes to the metallic ftate, and the liquor becomes of 
the colour of vermillion. Expofed to heat at a low tem ¬ 
perature, or in balneum marise, a thick matter of a dark 
red colour is foon perceived to float in a liquid, which 
had hitherto held it in folution. Separate this matter by 
filtration, and then prefs it: it crumbles eafily between 
the fingers, and falls to powder ; it has neither fmell nor 
tafte ; by expdfure to the air, or to a gentle heat, it be¬ 
comes black. Parmentier and Deyeux are of opinion, 
that this fubftance is the albumen of the ferum, com¬ 
bined with the colouring matter. 
The colouring matter, diftilled to drynefs in a retort, 
leaves a folid mafs, whence may be difengaged carbonated 
hydrogen gas, and fulphurated hydrogen gas. During 
the operation, the produfts are, a fetid oil, and Pruffiat 
of ammoniac; the coal contains, carbonats of foda and 
lime, muriat of loda, phofphats of foda and lime, and 
iron. Pure colouring matter contains, moreover, albu¬ 
men, and fome foda not free, but in combination with 
albumen, gelatin, and iron. 
Of the Fibrin. —If frefh-drawn blood be agitated, 
and ftirred about with pieces of wood, minute white 
flocks will be found flicking to them: this is fibrin, or 
the fibrous port of blood. This fibrous matter may be 
feparated from the clot by waffling. Put the clot in a 
hair fieve; pour water over it in a thin ftream ; rub and 
wafti till the water has taken away all the colouring mat- 
1 
ter; what remains is the fibrin, which is white. Or, in¬ 
dole the clot in a cloth, and work it between the hands 
in a tub of water ; the foluble part feparates by degrees ; 
the refidue is the fibrin. This fubftance is of a peculiar 
texture: by the folar microfcope, no red globules are 
perceptible, only a kind of minute filaments formed into 
branches. It is infipid, and contains no faline matters. 
The aftion of fire diftinguifhes its nature from the al¬ 
bumen, which burns and boils up without noife; but fi¬ 
brin fhrinks up and flies like parchment. By dillillation 
in a ftrong heat, it gives out a thick phlegm, which Hicks 
to the fides of the vefiel, catching the flocks which fwim 
about in the liquor; next comes over a thick fetid oil, 
and at the fame time a fetid gas, Which adheres very 
ftrongly to woollen rags; carbonat of ammoniac is ob¬ 
tained alfo unfaturated with acid, and feveral other falts, 
at prefent little known. Its coal is denfe, of a cryftal- 
line form, bright, folid, refembling carbure of iron, diffi¬ 
cult to burn, furnifhing calcareous phofphat, and pure 
carbon. 
Fibrin, expofed to damp air, fwells and puffs up, and 
has a fmell which exhibits the beginning of putrefaftion ; 
it is faint and naufeous. In a dry air it dries up. Put 
into a vefiel with a little water, and left for a confiderable 
time, it is converted into a foft pulpy matter like fat. 
Soaked a long while in a confiderable quantity of water, 
it rots. Boiling water only hardens it, depoliting a little 
gelatin ; but it can neither be converted into gelatin, nor 
into glue. It is not changed by combuftible bodies: char¬ 
coal, phofphorus, fulphur, &c. have no aftion upon it. 
It takes no oxygen from the metallic oxyds. 
With weak nitric acid, at 20 0 of heat, azot is produced; 
this is then difl'olved with effervefcence, and nitrous gas 
is difengaged; the refidue furnifhes oxalic acid, a little 
malic acid, and lome acetous acid. At the furface of the 
vefiel there is a fatty liibftance, fimilar to what floats on 
the nitric acid. The muriatic, acetous, and acetic, acids, 
difl'olve fibrin ; water and alkalis precipitate the fibrous 
part united with acids, but no longer with the fame pro¬ 
perties. 
The concentrated fulphuric acid afts upon fibrin, by 
changing its colour to yellow, brown, and at length to 
black; it thickens it alfo. The fulphuric acid does not 
undergo decompoiition, unlefs it was very weak ; in that 
cafe it pafl'es to the ftate of fulphureous acid; water is 
formed with the oxygen which has been feparated from 
the fulphuric acid, and the hydrogen of the fibrin, which 
is difengaged during the combination of the fibrin with 
the acid; carbon is precipitated, and the fulphuric acid 
remains weaker. Acetous acid and ammoniac are like- 
wife produced ; which proves that fibrin contains hydro¬ 
gen, oxygen, carbon, and azot. 
Cauftic alkalis diffolve fibrin with violence, when mixed 
with water. By diftillation, an ammoniacal fubftance is 
obtained, as hydrogen, oxygen, azot, and carbon. 
Of MILK. 
This is a liquid peculiar to females, whofe principal 
ufe is to nourifli the young animal. The human race, 
quadrupeds, and cetaceous animals, are the only crea¬ 
tures that furnifh milk : .ill others are deftitute of the or¬ 
gans which fecrete this fluid. In the changes which milk 
undergoes, feveral caufes are to be confidered : the aftion 
of heat, of air, of acids, oxyds, &c. Milk, expofed to 
the fire, fwells up, rifes in a mafs, and a pellicle is formed 
on its f urface, which is renewed as often as it is removed, 
till all the cafeous or cheely part is feparated ; for, accord¬ 
ing to Parmentier and Deyeux, it is the cafeous part 
whith forms thel'e pellicles. Diftilled with a very gentle 
heat, che firft produft is an infipid inodorous water ; after 
fome time, this water grows turbid, and becomes putrid, 
with a fmell of ammoniac ; it is ulually about a f'eventh 
or an eighth part: then the milk thickens, and collefts 
into a vifcous mafs. When it has boiled, it is always 
thicker, becaufe it has loft a little water; if it has not 
been 
