196 PAINTING MATERIALS
method has been largely displaced since about 1920 when a way was found for
synthesizing methyl alcohol from carbon monoxide and hydrogen. The result is
a pure product known as methanol and made more cheaply than that from wood
distillation.
When pure, methyl alcohol has an odor about like that of ethyl alcohol. It is
a clear liquid and boils at 66°C. As a solvent, it acts about as does ethyl alcohol
including solution of shellac. It is the basis of many paint removers and is much
used as a denaturant for ethyl alcohol because it does not affect the properties
of the latter as a solvent, and it can not be easily separated from it by distillation.
The vapors of methyl alcohol are much more poisonous than are those of ethyl
alcohol. Unlike the latter, it is oxidized in the system with the formation of
formaldehyde and formic acid. The vapor is flammable.
Methyl Cellosolve (see Ethylene Glycol Monomethyl Ether and Glycol Ethers).
Methyl Ethyl Ketone (CH3COC2H6). This solvent is like acetone, except ethyl
replaces one methyl group of that compound. Usually made by the dehydro-
genation of secondary butyl alcohol, it can also be obtained from wood distillates,
though that product contains a considerable amount of acetone. The evaporation
is somewhat slower than that of acetone, but the solvent action is about the same
as is the odor. It acts well on cellulose acetate. It is a colorless, flammable liquid,
boiling at 76.6°C. As a commercial product, it contains methyl acetate and
methyl alcohol.
Methyl Isobutyl Ketone (hexone [(CH3)2CHCH2COCH3H). As a medium-
boiling ketone, this solvent is useful in mixtures for lacquers and varnishes. Un-
like the lower ketones, it is only slightly miscible with water (1.9 per cent). It is
colorless and stable, not highly toxic or flammable. The boiling point is n6°C.
Methylated Spirit (see Denatured Alcohol).
Methylene Chloride (dichlormethane [CB^CU]), a clear liquid resembling
chloroform, is produced by the chlorination of methane. It is the most volatile
of the chlorohydrocarbons and boils at 4£°C., but has a very low flammabillty.
It is a strong solvent for oils, resins, rubber, and some cellulose derivatives.
Because of its action on linoxyn, it is included in many paint removers. Care is
required in handling it because of its volatility, but it is least dangerous physio-
logically of the chlorohydrocarbons and is stable to light and moisture.
Mineral Spirits (white spirits). As a vague synonym of * mineral thinner *
and * petroleum thinner,' the term designates a rather wide range of petroleum
distillates and has also come to mean a particular kind of thinner suitable for
paint and varnish. The solvent is prepared from petroleum bases which may con-
tain naphthenic hydrocarbons and are free from those sulphur and unsaturated
hydrocarbons of the olefin series which give an objectionable odor. It boils be-
tween 150° and aio°C., but the distillation range varies according to source and
refinery. Some distilleries offer various grades with differences in boiling range
and flash point.