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

STRUCTURAL SUGGESTIONS 235
the bombardment of the water molecules (Brownian move-
ment) to keep them suspended, such aggregates will settle.
Emulsoids are dehydrated and coagulated by excessive
amounts of salts, by nitric acid, sometimes by heat and by
shaking. Thus if it is necessary to shake an emulsion a great
deal, in handling, or shipping, or stirring to counteract settling,
the particles (having lost their full protective coats by dis-
turbance) may coagulate an amount sufficient to destroy the
emulsion.
It is the non-adhesive substance used to coat the dispersed
colloidal particles that is known as the emulsifying agent,
and such agent must be capable of being colloidally dispersed
also. The emulsifying agent selected, however, must be such
that the adsorptive power of its colloids is less than that of the
colloidall}^ dispersed basic substance being emulsified, else the
dispersed protective colloids of the emulsifying agent will not
be held to the surface of the colloidal particles of the basic
material, but the reverse will occur, and the colloidal particles
of the emulsifying agent will become coated by the dispersed
colloids of the basic material. The adsorptive power of an
adhesive type of colloidal particle, for colloidal particles of a
non-adhesive and protective character, is apparently increased
by the simple addition of a flocculating agent that will tend
to coagulate or unite the protective colloids in larger aggre-
gates about the basic colloids and thus give the basic colloids
a certain measure of greater protection or isolation one from
another.
If even a faint conception of colloid chemistry, and par-
ticularly the preparation and holding of emulsions, is possible
from the foregoing paragraphs, then a consideration of the
preparation, handling, shipping and application of asphalt
emulsions can follow.
Asphalt, as has been noted, is a colloidal substance; it is
one that may be colloidally dispersed in water by admixture
of the molten material with a hot aqueous alkaline solution ;
it is a material that is capable of being mechanically dispersed
in a colloidal state in water that has had its high surface
tension relieved. But to emulsify asphalt, that is, hold it in
colloidal suspension, requires the addition of a suitable emulsi-