THE VOLATILE PART OF PLANTS. 99 
cially if a little potash lye be added, it dissolves in a few 
days to a clear liquid, which coagulates on heating or by 
addition of metallic salts, in the same manner as a solu- 
tion of albumin. In very dilute chlorhydric acid, it swells 
up, but does not dissolve. 
Exp. 48.—Observe the separation of blood into clot and serum; co- 
agulate the albumin of the former by heat, and test it with warm chlor- 
hydric acid. Tie up the clot in a piece of muslin, and squeeze and wash 
in water until coloring matter ceases to run off. -Warm it with nitric 
acid as a test. 
Fleshfibrin.—If a piece of lean beef or other meat be 
repeatedly squeezed and washed in water, the coloring 
matters are gradually removed, and a white residue is ob- 
tained, which resembles blood-fibrin in its external char- 
acters. It is, in fact, the actual fibers of the animal muscle, 
and hence its name. It is characterized by dissolving in 
very dilute chlorhydric acid, (one part acid and 1,000 of 
water) to a clear liquid, from which it is again separated 
by careful addition of an alkali, or a solution of common 
salt. 
Vegetable sibrin.—When wheat-flour is mixed with a 
little water to a thick dough, and this is washed and 
kneaded for some time in a vessel of water, the starch and 
albumin are mostly removed, and a yellowish, tenacious 
mass remains, which bears the name gluten. When wheat 
is slowly chewed, the saliva carries off the starch and other 
matters, and the gluten mixed with bran is left behind— 
well-known to country lads as “ wheat-gum, a 
Exp. 49.—Wet a handful of good, fresh, wheat flour slowly with a lite 
tle water to a sticky dough, and squeeze this under a fine stream of 
water until the latter runs off clear. Heat portion of this gluten with 
Millon’s test. 
Gluten is a mixture of several albuminoids, and contains 
besides some starch and fat. Vegetable-fibrin is dissolved 
from it by alcohol, and separates on removitig the alcohol 
by evaporation. 
The albuminoids of crude gluten dissolve in very dilute potash-lye, 
