78 PHILOSOPHY OF ZOOLOGY. 
the urine of cows, from which it is extracted in France for 
commercial purposes. 
F. Oxalic Acid.—This acid has hitherto been found 
only in certain urinary calculi in union with lime. 
G. Acetic Acid.—This acid has been detected in milk in 
union with potash, by BErzextus. 
H. Malic Acid.—This acid has hitherto been found in 
company with the formic acid, in the liquor obtained from 
the red ant. 
Tn this short enumeration of the prmeiples which enter 
into the composition of animals, we perceive that carbon, 
hydrogen, oxygen and azote, are found in the greatest 
abundance. By combining in different proportions, they 
exhibit a grcat variety of separate substances. The 
earthy salts are likewise abundant; and when they occur 
in a separate state, they strengthen the albuminous frame- 
work, and form the skeleton, giving stability to the body, 
and acting as levers to the muscles. The alkaline salts 
occur in the greatest abundance in the secreted fluids. 
These different principles, variously modified and mixed, 
constitute the different parts of the animal frame. ‘These 
have been divided into twe kinds, —FVuids and Solids. 
The fluids consist of those juices which are obtained 
from our food and drink, such as the chyle, and are termed 
crude; of the blood, prepared from the crude fluids, and 
destined to communicate to every part of the body, the 
nourishment which it requires, and of those fluids which are 
separated from the blood in the course of circulation, such 
as the bile, and termed Secreted Fluids. These are all 
contained in appropriate vessels, and are subject to motion 
and change. 
The Solids are derived from the fluids, and are usually 
divided into the soft and hard. The sofé solids consist 
