SOLVENTS AND DILUENTS 197
Mineral Thinner (see Petroleum Thinner).
Morpholine is a clear liquid with a musty and ammoniacal odor. The chemical
formula is O : (CH2CH2)2 : NH; the boiling point is I28.9°C. It is miscible in all
proportions with water, and dilute solutions boil or evaporate with little change
in composition. A constant alkalinity is maintained in the solution and in the
distillate. Being mildly alkaline, it forms soaps with fatty acids and so may be
used as an emulsifying agent. Since in its structure it is a ring compound, combin-
ing an ether and an amine, it is a strong solvent for dyes, waxes, shellac, and for
casein. It is one of the few available solvents which has a direct effect on a thor-
oughly hardened linoxyn film.
Naphtha. In the technical literature on solvents and diluents, there is some
confusion about this term. It comes from the Greek, va4>day and, in turn, from the
Acadian, naptu (see R. J. Forbes, * Petroleum and Bitumen in Antiquity,* AmUx>
II [1938], p. 76). Originally the word was used for crude petroleum or vapor
coming out of the earth in regions of the Near East. Recently it has been applied
to the volatile distilled products of petroleum and coal-tar. Petroleum naphtha,
distilled in the range, 100° to i6o°C, is from paraffin or naphthenic hydrocarbons
(see V. M. and P. Naphtha). Coal-tar naphtha, a crude distillate, contains chiefly
benzene and its hcmologues. Solvent naphtha is a mixture of toluene, isomeric
xylenes, cumene, and other coal-tar hydrocarbons after the separation of benzene
from coal-tar naphtha by fractional distillation.
Oil of Spike Lavender, a product similar to turpentine, is obtained by the
distillation of spike lavender (Lavandula spied). This is different from the lavender
oils used in perfumes, for that comes from the dried tops of lavender flowers. Oil
of spike is a colorless liquid, boiling between 170° and aoo°C, and is less volatile
than turpentine. A solvent for soft resins, it is frequently called for in old recipes
for spirit varnish. It may have been used more for its odor than for its solvent
properties. According to Doerner (p. 122), Rubens used it occasionally, but con-
sidered it to be inferior to oil of turpentine.
Oil of Turpentine (see Turpentine).
Paint Remover* This name covers a large group of commercial preparations
made for the purpose of softening and dissolving paints and varnishes. Most of
them are mixtures of organic solvents, with a small amount of paraffin wax which
retards evaporation and keeps the solvent itself in contact with the paint for a
long time. Ammonia is a common ingredient also. With it are apt to be acetone,
methyl alcohol, and benzene. To reduce flammability, chlorinated hydrocarbons
like trichlorethylene are added. Many such mixtures are patented. Speed and
completion of solution in a paint remover, as in any single solvent, are dependent
upon various factors in the paint and on the combination of materials used on it.
Oil films thoroughly dried and containing pigment are very slow to dissolve and
are strongly resistant to the usual organic solvents. For them the type of paint
remover which contains strong alkalis is more effective. Some of these with sodium