We have mentioned _lac-lake_ and _lac-dye_ in page 12. Lac-lake is of very uncertain quality, having many heterogeneous substances mixed with it. _Lac-dye_ is very superior to lac-lake. Lac-dye is much used for dyeing woollen yarn scarlet and crimson, for carpets and hearthrugs. It is used with a peculiar spirit, which may be purchased of the dry-salters. Some think that this colouring material is nearly equal to cochineal; the author has, however, never seen any thing dyed with it equal to the colour obtained from cochineal, although it affords, nevertheless, a good scarlet. Lac-dye is used by being powdered and put into a stone pan, (the quantity must be in proportion to what is likely to be used), with a portion of the above-named _lac-spirit_ sufficient to make it about as fluid as treacle; it must be stirred with a glass-rod or a tobacco-pipe. Some use alum and tartar as a preparation, and some not. After putting the mixture of lac-lake and spirit in the copper with a proper quantity of water, add the goods and work them at a boiling heat. For _scarlet_ add quercitron bark, for crimson, _archil_. Lac-dye may be, however, prepared for dyeing, by submitting it, in _powder_, in a leaden vessel, to the action of sulphuric acid, in the proportion of not more than one part to two of the dye; and after the lac-dye is dissolved, the acid may be neutralized by carbonate of soda. With suitable mordants to the cloth or yarn, the colour may be then applied. Other processes for the employment of this dye are also adopted, but we have no room to detail them. (See _Ure's Notes on Berthollet_.) _To dye worsted yarn a_ CRIMSON. Proportion of wool, one pound; of _alum_, two ounces and a half; of _white tartar_ in powder, one ounce and a half. Having the water properly cleared by bran, let the alum and tartar be boiled in it; when it begins to boil, stir the mixture well, and put in the worsted, which boil in the liquor for two hours; then prepare a fresh liquor for the _cochineal_, one ounce of which, in powder, is to be used for every pound of wool; when it begins to boil, stir it well, put in the worsted, and boil it till the liquor in the vessel is free from colour, it having parted with the colouring matter of the cochineal, which should now all be upon the worsted. If a series of shades be required, less quantities of cochineal, alum, and tartar, must be used; the lightest shade is dyed first. _The preparation of archil to finish the_ CRIMSON.