m 
table substances in general, as appears from the 
statements given in the Third Lecture, the propor- 
tions are far from having the same simple relations 
as in the binary compounds capable of being made 
artificially, such as acids, alkalies, oxides, and in 
salts. 
Fibrine constitutes the basis of the muscular 
fibre of animals, and a similar substance may be 
obtained from recent fluid blood; by stirring it 
with a stick the fibrine will adhere to the stick. 
It is not soluble in water ; but by the action of 
acids, as Mr. Hatchett has shown, it becomes 
soluble, and analogous to gelatine. It is less 
disposed to putrefy than gelatine. According to 
M. M. Gay Lussac and Thenard, one hundred 
parts of fibrine contain 
Of carbon 
- 53.360 
— oxygene 
- 19.685 
— hydrogene - 
7.021 
— azote 
- 19-934 
Mucus is very analogous to vegetable gum in its 
characters ; and as Dr. Bostock has stated, it may 
be obtained by evaporating saliva. No experi- 
ments have been made upon its analysis ; but it is 
probably similar to gum in composition. It is 
capable of undergoing putrefaction, but less rapidly 
than fibrine. 
Animal fat and oils have not been accurately 
analysed ; but there is great reason to suppose 
that their composition is analogous to that of 
similar substances from the vegetable kingdom. 
Albumen has been already referred to, and its 
analysis seated in the Third Lecture. 
