64 PHILOSOPHY OF ZOOLOGY. 
which remains is more copious than that which is left by 
the two preceding substances. It is incinerated with difficul- 
ty, as a glassy coating forms on its surface, and excludes the 
action of the air. ‘The residue consists of the phosphate af 
soda and lime, together with carbonate fof lime. Fibrin 
we have scen, exists in the blood, and was formerly calle. 
the fibrous part of the blood. It likewise exists in all 
muscles, forming the essential part or basis of these organs. 
It exhibits many remarkable varieties, as it appears in the 
flesh of quadrupeds, birds and fishes. 
4. Extractive-—When the flesh of an animal is boiled 
for some time in water, the fibrin and albumen remain, 
and the solution contains the gelatine and other substances 
soluble in water. If the solution be evaporated to dryness, 
and treated with alcohol, the gelatine remains undissolved, 
and a solution of extractive is obtained. It is the sapona- 
ceous extract of meat of Roverie, and the osmaxome of 
THENARD. 
When freed from the alcohol by evaporation, the ex- 
tractive is of a reddish-brown colour, semitransparent, has 
an acrid taste, and an odour similar to the juice of meat. It 
attracts moisture from the air, and becomes soft. It is so- 
Juble in alcohol and water. It is precipitated by the in- 
fusion of nut-galls. When heated, it swells, and emits 
the odour of burning animal matter. Its charcoal affords 
carbonate of potash. When distilled, it yields ammonia. 
Its constituent principles appear to be the same with those 
of the three preceding substances. According to Berzr- 
LIus, it is always combined with the lactate of soda *. 
Extractive exists in the muscles of animals, in the blood 
and in the brain. It communicates the peculiar flavour 
of meat to soups. In the opinion of Fourcroy, the 
brown crust of roasted meat consists of it. 


* Annals of Phil. ii. p. 202. 
