Lac, or Gum-Lac, is a kind of wax, of which a species of winged ants form cells upon trees, like honeycombs. In these cells remain some of the dead insects, which give a red colour to the whole substance of the lac. That called stick-lac is the wax adhering to some of the small branches of the tree, and which is unprepared. This lac, when separated from the adhering sticks, and grossly powdered, and deprived of its colour by digestion with menstrums, for the sake of the dyes and other purposes, is called seed-lac; and lastly, when the stick-lac is freed from impurities, by melting it over a gentle fire, and formed into cakes, it is called shell-lac. Lac is insoluble in water; and difficulty soluble in spirit of wine, which for that purpose must be well dephlegmated. According to Newman, 16 ounces of seed-lac, distilled in an open fire, yielded nine ounces and six drams of a butter or thick oil, one ounce six drams of a watery liquor neither acid nor alkaline, and a residuum weighing two ounces and a half. It is used in the preparation of spirit varnishes, for the making of sealing-wax, and as a colouring material for dying scarlet. The colour given by lac is less beautiful, but more durable, than that given by cochineal. To render the colouring matter of the lac diffusible in water, so as to be applied to the stuffs to be dyed, Mr Hellot directs the following process: Let some powdered gum-lac be digested during two hours in a decoction of comfrey root, by which a fine crimson colour is given to the water, and the gum is rendered pale or straw-coloured. To this tincture, poured off clear, let a solution of alum be added; and when the colouring matter has subsided, let it be separated from the clear liquor and dried. It will weigh about \( \frac{1}{7} \) of the quantity of lac employed. This dried felsula is to be dissolved or diffused in warm water, and some solution of tin is to be added to it, by which it acquires a vivid scarlet colour. This liquor is to be added to a solution of tartar in boiling water; and thus the dye is prepared.