C H E M ] 
ture below boiling water, it coagulates; and this coagu- 
lum, prefled and calcined, fliews to the magnetical needle 
unequivocal marks that it contains iron. 
By diftillation with a naked fire, in clofed veflels with, 
the pneumatic apparatus, blood affords, i. Pruffiat of 
ammoniac, z. A very fetid thick oil. 3. Sulphurated 
hydrogen gas, fetid. 4. Carbonated hydrogen gas. 5. The 
carbon which remains is in bright cryltals, refeinbling 
carbure of iron ; it contains, 6. Phol'phat of foda. 7. Phol- 
phat of lime. S. Carbonat of loda. 9. Iron. This coal 
is very difficult to reduce; its allies are of a red colour; 
the iron may be feparatecl by waffling, or by the hiagnet. 
The prefence of iron in blood may be proved by only 
mixing with it a little of the nut-galls in powder; in iefs 
than forty-eight hours the mixture becomes perfectly 
black. 
Blood may be calcined in a crucible; in which cafe 
only fixed products are obtained. Diftil dried blood, 
and boil the liquid product with quicklime ; a faline cal¬ 
careous combination is produced. Decompofe this fait 
with phofphoric or fulphuric acid, by diftillation in a re¬ 
tort ; and an acid comes over, difcovered by Berthollet, 
and called by him zoonic acid. 
Frefti blood mixed with oxygen, acquires a colour 
more lively and red. Mixed with hydrogen gas, it in¬ 
clines to a brown colour, becomes dull, and at length 
dark brown. Blood unites with water in all proportions, 
difl'olves therein very well, communicating a beautiful 
purple colour. This mixture, when heated, depolits 
flocks, and the blood coagulates. Mixed with two parts 
of water, and evaporated, it forms a liquor fimilar to bile, 
but not of the fame properties. 
The metallic oxyds, of whatever defcription, all thicken 
blood. Acids immediately coagulate it, and change its 
colour, which proves that no free acid exifted previoufiy 
in the blood ; for, injeft an acid into the vein of a living 
animal, and as loon as the vein is tied up, the animal 
dies. By filtration, and evaporating of the filtrated liquor 
to drynefs by a gentle fire, and fubfequent lixiviation of 
this relidual matter, fucli neutral falts are obtained, as 
foda forms with each acid; any of which maybe indif- 
criminately ufed. Neutral l'alts prevent the coagulation 
of the blood. 
Blood is diffolved by cauftic alkalis; on which princi¬ 
ple depends the mode of forming Pruflian blue, or Pruf¬ 
fiat of iron, as defcribed under our inveftigation of that 
■metal, p. 300. 
Of the Serum.— Hitherto we have fpoken of blood 
in general, or colleftively ; we mull now fpeak of its con- 
tuent parts. The ferous part, though fufceptible of much 
variety, is, in general, a liquid thicker than water; fo 
that, in fome cafes, it refembles the white of an egg, at 
other times it may take the confidence of a fyrup, but 
moft commonly it is like a mucilage, or gum diffolved in 
water. 
According to the experiments of Deyeux, if ferum be 
expol’ed to a gentle heat, a greyifh brown fcum is found 
at the furface of the veffel; this is diftindt from another 
which lies at the bottom, and is thicker. That which 
occupies the upper part is yellow, tranfparent, and tre¬ 
mulous; this is the gelatin ; the lower part is concrete, 
whiter, and more firm, and is the albumen. Hence it ap¬ 
pears that the ferum contains two diftindt parts, -which 
are obtained by evaporation, the albumen, and the gelatin. 
If ferum be expofed to 6o° of heat, the gelatin remains 
in folution with the albumen, which foon coagulates. By 
a ftronger heat, it dries; the hydrogen is fet free, and 
forms a water with the oxygen of the atmofphere; the 
water thus produced is reckoned to be one-feventh part 
of the bulk of the ferum. Then a folid mafs remains, of 
a cryftalline appearance and hyacinth colour, which af¬ 
fords, 1. Carbonated hydrogen gas. 2. Sulphurated fetid 
hydrogen gas. 3. Pruffiat of ammoniac. The refiduary 
coal contains, carbonats of foda and of lime, muriat of 
foda, phofphats of foda and lime, but no iron. The ferum 
VOL. IV. No. 202, 
S T R Y. 357 
prefently changes its appearance by expofure to the air: it 
aflumes a yellow colour, then red, and afterwards green : 
it gives out a very difagreeable frnelL, and then affords am- 
moniacal carbonat: it inclines, therefore, to putrefaction. 
Serum unites with water in all proportions: with aerated 
water it changes its nature, but not with common water. 
Mixed with the former, it becomes red, and precipitates 
white flocks; with the latter, it lofes its tranfparency. 
Mix ten parts of water with one of ferum ; a membrane 
is formed on the furface of the liquor; by evaporation, 
gelatin is feparated. A mixture of two parts of water, 
with one of ferum, becomes folid by the aftion of heat. 
If lime-water be poured into water containing a fmall 
quantity of ferum, calcareous phofphat is precipitated. 
Serum alfo undergoes an alteration by being combined 
with oxygen gas. 
Deyeux and Parmentier have proved that ferum con¬ 
tains fulphur; by heating albumen in a filver faucepan, 
they found that the filver loft its metallic brightnefs. 
Thele chemifts even fucceeded in feparatjng the fulphur; 
it is only neceflary to triturate in a glafs mortar fome of 
the albumen, with a few drops of a welMaturated folu¬ 
tion of lilver; leave the mixture to digeft for a time ; 
then warm it, after diluting it a little with water; and 
l'ome greyilh filaments will appear, which become black 
by degrees, and exhibit at the bottom of the velfel a 
precipitate from which fulphur may be extracted. Laft- 
ly, If pure potalh be boiled with the albumen and water, 
a liquid is obtained, which, ftrained and mixed with ace¬ 
tic acid, gives out an hepatic odour, capable of changing 
the colour and brightnefs of filver. 
If ferum be mixed with an oxyd which readily parts 
with its oxygen, as mercury, for inftance, it takes up the 
oxygen, and the ferum becomes firm and bard, as if 
baked ; but the mixture mult be made in the cold. Acids 
alfo give a confiftence to ferum, by coagulating it. This 
mixture being filtrated, and the fluid evaporated, the 
neutral fait, which the acid made ufe of forms with fo¬ 
da, is obtained; which proves that this laft fait exifted 
in a difengaged ftate, and poflefled all its properties in 
the ferum. The very cauftic alkalis, uncombined with 
water, coagulate the albumen; but ammoniac dift'olves 
and decompofes it. If weakened alkalis be then added, 
they dift'olve the thickened albumen. Alkalis in gene¬ 
ral render the ferum more fluid by a kind of folution. 
If ferum, newly feparated from the blood, be mixed 
with alcohol, the mixture loon becomes turbid, and the 
albumen is feparated. If a very pure alkali be poured 
over the matter thus feparated, it difl'olves immediately, 
and the water with which it may be mixed, will become 
tranfparent. 
Serum does not decompofe the calcareous and albu- 
menous neutral falts; but it decompofes the metallic 
falts. If a nitric folution of mercury be poured into the 
ferum, there is a role-coloured precipitate; Fourcroy at¬ 
tributes this to the calcareous phofphat contained in the 
ferum. 
Of the Coagulum, or Clot. — Parmentier and 
Deyeux chemically examined the clot of blood. They 
remark, that it preferves its fmell and confiftence for 
three, four, or five, days, in a veffel not very wide, and 
fet in a cool place; for in warm air it loon foftens and 
putrefies ; its fmell then changes, and becomes very dif- 
agreeable. If the clot be feparated from the ferum, it 
may be preferved, and even entirely dried, without al¬ 
teration, efpecially if kept in a warm place : its colour, 
in that cafe, is of a very deep red, with a kind of fenri- 
tranfparency at the edges. If the clot, feparated from 
the ferum, be left to drain for an hour, by then heating 
it over a water-bath, it takes a firmer confiftence, and the 
liquor which drops differs in no refpeft from ferum; it 
contains as much albumen as that from which'it was pre¬ 
vioufiy feparated. 
Clot of blood, thrown into a certain quantity of boil¬ 
ing water, gives it a milky appearance; a fcum riles at 
4. Y the 
