Note: In general, soaps are of two classes, hard and soft.
Calcium, magnesium, lead, etc., form soaps, but they
are insoluble and useless.
The purifying action of soap depends upon the
fact that it is decomposed by a large quantity of
water into free alkali and an insoluble acid
salt. The first of these takes away the fatty
dirt on washing, and the latter forms the soap
lather which envelops the greasy matter and thus
tends to remove it. --Roscoe &
Schorlemmer.
{Castile soap}, a fine-grained hard soap, white or mottled,
made of olive oil and soda; -- called also {Marseilles, or
Venetian, soap}.
{Hard soap}, any one of a great variety of soaps, of
different ingredients and color, which are hard and
compact. All solid soaps are of this class.
{Lead soap}, an insoluble, white, pliable soap made by
saponifying an oil (olive oil) with lead oxide; -- used
externally in medicine. Called also {lead plaster},
{diachylon}, etc.
{Marine soap}. See under {Marine}.
{Pills of soap} (Med.), pills containing soap and opium.
{Potash soap}, any soap made with potash, esp. the soft
soaps, and a hard soap made from potash and castor oil.
{Pumice soap}, any hard soap charged with a gritty powder, as
silica, alumina, powdered pumice, etc., which assists
mechanically in the removal of dirt.
{Resin soap}, a yellow soap containing resin, -- used in
bleaching.
{Silicated soap}, a cheap soap containing water glass (sodium
silicate).
{Soap bark}. (Bot.) See {Quillaia bark}.
{Soap bubble}, a hollow iridescent globe, formed by blowing a
film of soap suds from a pipe; figuratively, something
attractive, but extremely unsubstantial.
This soap bubble of the metaphysicians. --J. C.
Shairp.
{Soap cerate}, a cerate formed of soap, olive oil, white wax,
and the subacetate of lead, sometimes used as an
application to allay inflammation.
{Soap fat}, the refuse fat of kitchens, slaughter houses,
etc., used in making soap.
{Soap liniment} (Med.), a liniment containing soap, camphor,
and alcohol.
{Soap nut}, the hard kernel or seed of the fruit of the
soapberry tree, -- used for making beads, buttons, etc.
{Soap plant} (Bot.), one of several plants used in the place
of soap, as the {Chlorogalum pomeridianum}, a California
plant, the bulb of which, when stripped of its husk and
rubbed on wet clothes, makes a thick lather, and smells
not unlike new brown soap. It is called also {soap apple},
{soap bulb}, and {soap weed}.
{Soap tree}. (Bot.) Same as {Soapberry tree}.
{Soda soap}, a soap containing a sodium salt. The soda soaps
are all hard soaps.
{Soft soap}, a soap of a gray or brownish yellow color, and
of a slimy, jellylike consistence, made from potash or the
lye from wood ashes. It is strongly alkaline and often
contains glycerin, and is used in scouring wood, in
cleansing linen, in dyehouses, etc. Figuratively,
flattery; wheedling; blarney. [Colloq.]
{Toilet soap}, hard soap for the toilet, usually colored and
perfumed.
2. To flatter; to wheedle. [Slang]