essence of turpentine and also in all the oils extracted by the distillation of tar.
This method is very old and can be applied to many hard rosins not soluble in their natural state.
Great care must be taken not to apply the heat too long or too fiercely, otherwise it will burn and so spoil the colour and deprive it of its properties.
Amber is much used in the manufacture of the most durable varnishes, particularly that used by painters and decorators.
Turpentine.—This is an aleo rosin and is the produce of certain plants of the coniferae family. It contains varying proportions of essential oils.
The commonest type is the most siccative, and by the addition of one part to sixteen of magnesia it will become hard.
It is completely soluble in alcohol. Another variety, Venice turpentine, is not siccative but easily dissolved in spirit.
It is a mixture of essential oils and rosins.
Elemi.—Elemi may be classed as a rosin. It is obtained from Brazil and Mexico. It is partially soluble in alcohol, water or ether.
