Description and references
Any salt of a fatty acid, usually made by saponification
of a vegetable oil with caustic soda. Hard soap consists largely
of sodium oleate (low titer) or of sodium palmitate or stearate (high
titer); soft soap, of potassium and sodium salts of coconut and/or
palm oil fatty acids. Rosin acid salts have detergent properties
and are often incorporated in laundry soaps. Shaving soaps contain
glycerol and gum to prevent rapid drying. Medicated soaps contain
antiseptics such as phenols or mercury salts. Soaps also may be prepd
from the fatty acid and an amine, e.g., triethanolamine.
Nonalkali-metal salts of the fatty acids are water insol and as such
have certain uses.
Properties
Hard soap (olive-oil castile) is a white or yellowish
white powder or bar, sol in water, alc. The aq soln is alkaline due
to hydrolysis; the alc soln is only slightly alkaline. Transparent
hard soap is obtained by adding additional glycerol during saponification.
Floating soaps are made by adding air after saponification during
the so-called “crutching” process. Soft soap (green soap) is a yellowish-white
to brownish-yellow (or green) soft mass, more sol than hard soap.Use
Hard soap—detergent; in soln as a vehicle
for liniments; as ingredient of pills contg resinous drugs like aloe,
etc. Soft soap‐detergent; extern. as vehicle for active medicaments
applied in ointment form or liniment. Insoluble soaps—fungicides
(Cu), disinfectants (Pb, Cu, Hg), face powders and ointments (Zn),
waxes and polishes (Al), greases (Al, Ca), and surface coatings (Ca).
Therapeutic Category
Topical anti-infective. Antidote (mineral acid and heavy metal
poisoning).
Therapeutic Category (Veterinary)
Topically as detergent (cleansing agent)
and mild antiseptic. In liniments as counterirritant. Has been used
internally as laxative, antacid and as an antidote for mineral acids
and heavy metals.