Cork insulation; a complete illustrated textbook on cork insulation ...

STRUCTURAL SUGGESTIONS 237
"emulsion" would be to settle in the container, the particles
of asphalt simply being held apart by their coatings of non-
adhesive material ; and the disturbances of handling, shipping,
and stirring to counteract settling may sufficiently dislodge
the protective coatings from the asphalt particles to cause
enough coagulation to make the emulsion unfit for practical
use. The use of an unsuitable emulsifying agent, or incor-
rect proportions of ingredients, or insufficient heat, or other
errors of omission or commission, may conceivably be respon-
sible for an unsatisfactory emulsified asphalt product.
Back of it all, too, is this important fact : If a good grade
of a suitable asphalt is used as the basic material to be emulsified,
then vv^hen dehydrated on the w^alls of a building, or on
cork <strong>insulation</strong>, there will remain the same good grade of a
suitable asphalt as a protective coat; otherwise, not; if a poor
asphalt is emulsified, it remains a poor asphalt, always.
Emulsified asphalt is, of course, subject to freezing, which
is a serious objection to the shipping and handling of the
material in cold weather.
The exact determination of the constituents of an asphalt
emulsion is usually attended with considerable difficulty and
no predetermined scheme can be made applicable to all mate-
rials of this character. The following methods, how='ever, are
used by the United States Office of Public Roads and Rural
Engineering, according to Prevost Hubbard, and have yielded
reasonably satisfactory and fairly accurate results
Special Tests for Emulsions.
Fatty and Resin Acids.—In order to break up the emulsion, a 20gram
sample is digested on a steam bath with 100 cubic centimeters
of N/2 alcoholic potash. The digestion is carried out in a flask with
a reflux condenser for about 45 minutes. The solution is filtered
and the precipitate washed with 95 per cent alcohol. The filtrate is
evaporated to dryness, after which the residue is taken up with hot
water and any insoluble matter is filtered ofif. The aqueous solution,
which contains the potassium soaps of the fatty acids, is acidified
with dilute sulphuric acid and then shaken in a separatory funnel
with petroleum ether. The aqueous portion is drawn off and the
ethereal layer shaken up with cold water and washed twice, after
which it is evaporated in a weighed platinum or porcelain dish to
constant weight, first over a steam bath and then in a drying oven
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