by 1.6 (the specific gravity of nitro-glycerine),
thus: 10 grms. gave 14.5 c.c. nitro-glycerine, and 14.5 x 1.6 = 23.2
grms., therefore 100 would give 232 grms. nitro-glycerine. The points to
be noted in the nitration of a sample of glycerine are: the separation
should be sharp, and within half an hour or less, and there should be no
white flocculent matter formed, especially when the carbonate of soda
solution is added.

~Total Acid Equivalent.~ Mr G.E. Barton (_Jour. Amer. Chem. Soc._, 1895)
proposes to determine thus: 100 c.c. of glycerine are diluted to 300 c.c.
in a beaker, a few drops of a 1 per cent. solution of phenolphthalein and
10 c.c. of normal caustic soda solution are added; after boiling, the
liquid is titrated with normal hydrochloric acid (fatty acids are thus
indicated and roughly determined).

~Neutrality.~ The same chemist determines the neutrality of glycerine
thus: 50 c.c. of glycerine mixed with 100 c.c. of water and a few drops of
alcoholic phenolphthalein[A] are titrated with hydrochloric acid or sodium
hydroxide; not more than 0.3 c.c. normal hydrochloric acid or normal soda
solution should be required to render the sample neutral; raw glycerines
contain from .5 to 1.0 per cent. of sodium carbonate.

[Footnote A: Sulman and Berry prefer litmus as indicator.]

~Determination of Free Fatty Acids.~ A weighed quantity of the glycerine
is shaken up with some neutral ether in a separating funnel, the glycerine
allowed to settle, drawn off, and the ether washed with three separate
lots of water. The water must have been recently boiled, and be quite free
from CO_{2}. All the free fatty acid is now in the ether, and no other
soluble acid. A drop of phenolphthalein is now added, a little water, and
the acidity determined by titration with deci-normal baryta solution, and
the baryta solution taken calculated as oleic acid.

~Combined Fatty Acid.~ About 30 grms. of the glycerine are placed in a
flask, and to it is added about half a grm. of caustic soda in solution.
The mixture is heated for ten minutes at 150 deg. C. After cooling some pure
ether is added to it, and enough dilute H_{2}SO_{4} to render it
distinctly acid. It is well shaken. All the fatty acids go into the ether.
The aqueous solution is then removed, and the ether well washed to remove
all H_{2}SO_{4}. After the addition of phenolphthalein the acid is
titrated, and the amount used calculated into oleic acid. From this total
amount of f