488 
ANATOMY OF THE HORSE. 
fectly resolved itself into its component parts, but will be growing 
putrid. But draw a pint from a horse, and place it in a medium 
of the same temperature, and serum will continue to ooze from it 
even for a week afterwards. 
In fact, the tw r o most essential differences between human and 
horses’ blood, are,—1st. That the latter much more slowly resolves 
itself into its component parts ; and, secondly, that it possesses 
greater preservative powers against putrescency. 
Serum itself exposed to the temperature of 160° is converted 
into a solid, white, opaque mass; also the effect of coagulation. 
Mineral acids and alcohol wall likewise produce this change. It 
now resembles boiled w r hite of egg; and is found, in fact, to be 
the same in nature, viz. albumen . If the coagulum be cut or 
squeezed, a limpid fluid issues from it, that has been termed the 
serosity . 
“ The most important chemical properties of albumen,” ob¬ 
serves Dr. Bostock, “ while in its liquid form, are its solubility 
in water, and the precipitates which it forms with the mineral 
acids, tan, and a variety of metallic salts. Of the acids, the 
muriatic is supposed to combine w T ith it the most readily, and is 
therefore employed as one of the most delicate tests of its pre¬ 
sence in a substance where we expect it to exist. Tan forms 
with albumen a dense precipitate of tough consistence, and inso¬ 
luble in water. A variety of the metallic salts precipitate albumen, 
and, like the acids, serve as very delicate tests of its presence; of 
these probably the corrosive sublimate, or the bichloride of mer¬ 
cury, is the most delicate, and at the same time the most dis¬ 
criminate, as it appears to have no action upon any other of the 
animal substances which enter into the composition of the albu¬ 
minous fluids.” When coagulated, albumen becomes completely 
insoluble in w 7 ater. 
The serosity exists in a comparatively very small quantity, 
and can only be obtained by dividing the albuminous coagulum 
and allowing it to drain, or by expression, or by washing it in 
water. It has been particularly examined by Dr. Bostock, and 
found to contain an animal matter which is not albumen ; and 
whose nature it is difficult to make out, in consequence of its 
being always found united with soda, and a variety of other salts, 
from which it cannot be separated, without being, at the same 
time, decomposed. To this substance Dr. Marcet has applied 
the name of muco-extractive matter; while Dr. Bostock prefers 
styling it the uncoagulable matter of the blood. 
