798 
lated and uncoagulated state. When coagulated, 
the separation of fibrin and albumen cannot be 
effected by any means with which we are ac- 
quainted, and, indeed, the first authorities 
differ when they attempt to decide which of 
the two they have to deal with, if they occur 
in the coagulated state. When uncoagulated, 
their separation and quantitative determination 
may be effected with considerable accuracy. 
Pure fibrin, when moist, is white and some- 
what elastic, is insoluble in water, alcohol, or 
ether. It is readily taken up by strong acetic 
acid, and from this solution it is precipitated 
by ferrocyanide of potassium (prussiate of ‘pot- 
ash); fibrin also dissolves in solution of pot- 
ash; if, when thus dissolved, it be heated gently 
and the liquid neutralized by an acid, a white 
flocculent precipitate occurs, which redissolves 
in excess of acid, and the solution emits an 
odour of sulphuretted hydrogen. Strong nitric 
acid turns fibrin yellow, forming a yellow so- 
lution with gradual evolution of gas; in con- 
centrated hydrochloric acid it slowly dissolves 
with a rich violet colour. These are properties 
it possesses in common with albumen and ca- 
sein; but it is distinguished from them and 
from all other animal matters by its sponta- 
neous coagulation when removed from the living 
body. This furnishes us with a certain test 
of its presence when in the liquid form, and 
enables us to separate it in good degree from 
other bodies ; within its pores, however, is ob- 
_ Stinately retained a quantity of the fluid from 
which it has just separated itself, together with 
most of the globules and particles suspended 
in the secretion. It becomes necessary, there- 
fore, to wash out these ingredients, an opera- 
tion rendered possible by the insolubility of the 
fibrin in cold water. e coagulum from a 
known quantity of fluid is cut into very thin 
shreds by a sharp knife, tied in a piece of linen, 
and a gentle stream. of water allowed to fall 
upon it; from time to time the clot is gently 
kneaded and the washing continued; in the 
case of blood, till all traces of colouring matter 
are removed, or, where no colour is present, so 
long as may be deemed necessary ; the residue 
is then removed from the linen, dried, digested 
in ether to remove adhering fatty matters, again 
dried and weighed. A portion is then incinerated, 
the weight of the fixed matters determined and 
deducted from the gross weight of the dried 
fibrin, by which we obtain that of the organic 
matter.* 
Fatty matters.—Several peculiar oily sub- 
stances occur in the fluids and solids of the 
animal body. Among the saponifiable fats 
chemists have distinctly ascertained the pre- 
sence of margarin, elain, and butyrin; besides 
these we have cholesterin and serolin, which 
are not saponifiable by boiling in alkaline solu- 
tions, and there are others containing phos- 
phorus and sulphur, but their composition and 
properties are yet involved in uncertainty. Our 
* It has been objected that the insoluble nuclei 
of the red particles are retained in this process. It 
is, however, superior, both in the accuracy of its 
results and the facility of its performance, to any 
other method hitherto pro as its substitute. 
ORGANIC ANALYSIS. 
analytical processes for separating these bodies — 
are very imperfect ; the fats are all soluble in — 
boiling alcohol, and still more freely in ether. 
Cholesterin and serolin may be isolated from 
the other fats by boiling the residue, after eva- 
poration of the ether, with solution of caustic 
potash, as they remain undissolved by this’ 
menstruum, whilst the margarin, elain, and 
butyrin form soaps which are dissolved by the 
water. : a 
Serolin is an azotised fat, which has hitherto 
only been found in the blood ; it is readily dis- 
tinguished from cholesterin by its fusing 
being much lower, 97° F., whereas chole 
does not melt below 278°, and is found in 
blood only in minute quantity.. By pressing 
them between folds of filtering paper we mig 
therefore, if careful to maintain a temperatur 
near that of boiling water, effect a tole: 
complete separation of these bodies. ‘s 
from th 
POL 
Butyrin rapidly absorbs oxygen 
air, setting free a volatile acid, the butyric 
it possesses the peculiar odour of rayeid butte 
by which its presence is always easily reeog 
nized. : 
In analytical inquiries it is best to separ 
fatty matters by ether as the first step after t 
liquid has been evaporated to dryness; we m 
then safely proceed to determine the 
Albumen.—In chemical properties it d 
little from fibrin, excepting in the fact of 
requiring heat or some chemical agent to pi 
duce coagulation; towards nts it cc 
ports itself in the same way. When liq 
Its separation from fibrin and fats is effee 
as just described. The residue, after 
fats have been removed by ether, i 
gested in boiling water, and the residue 
washed ; the albumen remains upon the’ 
and must be dried and weighed. A g 
quantity is incinerated to determine the p 
portion of saline matters, which must be 
ducted from the weight previously fou 
uric acid existed in the solution, it woul 
mixed with the albumen. In case the colot 
ing matter of the blood were contained i 
fluid, a small part would remain mixed 
the albumen, and might be removed b 
gestion in alcohol acidulated with sul 
acid, by which the hematosin is dissolvet 
greater part, however, subsides by a 
the liquid to stand undisturbed in a tall 
for forty-eight hours. If the solution + 
free alkali, a part of the albumen is red 
on the addition of water; when, 
filtered liquid presents an alkaline rea 
should be very carefully and exactly 1 
by acetic acid, evaporated to dryness, at 
treated with hot water; the weight of this 
portion of albumen must be added tot 
obtained. Casein hardly ever occurs 
same solution with albumen; if pr 
would be separated by the aceti¢ aci 
manner me described. a 
Casein is distinguished from albumen 
non-coagulability by heat; when its s0 
are evaporated at a high tempe ,% 
luble skin or film forms upon 
which is almost characteristic, the ¢ 
: 
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