The New International Encyclopædia/Pearl Ash

PEARL ASH (so called on account of the color), or Potashes. Crude potassium carbonate obtained from wood ashes. The commercial product is made in Canada, as follows: Wood is burned in pits and the resulting ash spread on a stone floor, sprinkled with water, and worked till it is damp, frequently with the addition of a little lime. The damp ash is then placed in casks containing false bottoms, covered with straw and hot water poured over them. The liquid, which is drawn off from a plug hole at the bottom, is boiled down, and finds some use in this condition as a manure owing to the soluble potash that it contains. The crude pearl ash thus obtained may be purified by heating and then cooled, during which the sulphate and chloride, together with the insoluble matter, are separated out, while the clear supernatant liquid is drawn off and boiled down until it crystallizes. When sufficiently pure this product finds use in the manufacture of flint glass. Ordinary pearl ash is used principally, however, in the manufacture of soap.