This section is from the "Henley's Twentieth Century Formulas Recipes Processes" encyclopedia, by Norman W. Henley and others.
In many of the processes at present in use, whereby oils and fats are decomposed by steam at a high pressure, the time during which the oil or fat has to be exposed to high pressure and temperature has the effect of considerably darkening the resulting product. Hannig's process claims to shorten the time required, by bringing the steam and oil into more intimate contact. The oil to be treated is projected in fine streams into the chamber containing steam at 8 to 10 atmospheres pressure. The streams of oil are projected with sufficient force to cause them to strike against the walls of the chamber, and they are thus broken up into minute globules which mix intimately with the steam. In this way the' most satisfactory conditions for the decomposition of the oil are obtained.
Barbadoes tar....... 1 ounce
Linseed oil.......... 16 ounces
Oil turpentine....... 3 ounces
Oil vitriol........... 1/2 ounce
Add the oil of vitriol to the other ingredients very gradually, with constant stirring.
To dry oils for varnishes, paintings, etc., the most economical means is to boil them with shot, to leave them for some time in contact with shot, or else to boil them with litharge. Another method consists in boiling the oils with equal parts of lead, tin, and sulphate of zinc in the ratio of 1/10 part (weight) of the united metals to 1 part of oil to be treated. These metals must be granulated, which is easily accomplished by melting them separately and putting them in cold water. They will be found at the bottom of the water in the shape of small balls. It is in this manner, by the way, that shot is produced.