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546 DENTAL MEDICINE.

add glycerine. Clear shellac varnish may be prepared by first
making an alcohol solution of shellac in the usual way, and then
adding a little benzole, and the mixture well shaken. In from
24 to 48 hours the fluid will have separated into two distinct
layers, an upper alcoholic stratum, perfectly clear, and of a dark-
red color, while under it is a turbid mixture containing the im-
purities. The clear solution is drawn off with a pipe, or may
be decanted.
SILVER SULPHO-CARBOLATE—SILVER SULPHO-PHENATE.
Derivation.—Silver sulpho-carbonate is prepared from silver
carbonate and sulpho-carbolic acid. It occurs in the form of
white, prismatic needles, containing twenty-eight per cent, of
silver. It must be protected from light and air to prevent it
from splitting up into metallic silver and phenol.
Therapeutic and Dental Uses.— It is said to possess valuable
antiseptic properties, and to be preferable to nitrate of silver for
such purposes as the latter agent is employed, on account of its
non-corrosive action. Dr. Harlan speaks of it acting very well
in deep pyorrhoea pockets. It is soluble in water in three to ten
per cent, solutions.
SOD^ PHENAS—PHENATE OF SODIUM.
CARBOLATE OF SODIUM PHENOL SODIQUE.
Formula.—CgHgNaO.
Derivation.—Phenate or Carbolate of Soda is obtained by mix-
ing one part of caustic soda with five parts of carbolic acid, and
a small quantity of water, and evaporating the solution, the re-
sult being a saponaceous mass of acicular crystals of a light pinkish
color, which are converted by the heat into a fluid of an oily
consistence. It is freely soluble in creasote, carbolic acid and
water.
Medical Properties and Action.—Phenate of soda is hemostatic,
antiseptic and disinfectant.
Therapeutic Uses.—It is internally administered in the form
known by the French name of Phenol Sodique., in doses of gtt.
viij or gtt. X in a glass of water, in typhus and typhoid fevers, as