The principal Alum mordant is Acetate of Alumine, prepared as follows: Let 3 lbs. Alum and 3 ozs. chalk be dissolved in 1 gallon of warm water in an earthenware pan, add the chalk slowly to the Alum. Add 2 lbs. white acetate of lead, stir occasionally during 24 to 36 hours. Let it remain 12 hours at rest. Decant and preserve the clear liquor, being careful not to stir up the sediment. Pour 2 gallons of water on the sediment, and stir occasionally for 12 hours. Let it rest 12 hours. Decant the clear and add to the first lot. Bottle for use. It keeps about three weeks. Of the mordant 2 parts are diluted with 1 of water, and the silk is well worked in this for 10 minutes, after being wetted down. Steep for 12 hours, wring out and dry. Wet down again and return to the Alum liquor, work for 10 minutes, steep 12 hours, dry. When thoroughly dry, wash well in several changes of water before dyeing. For less bright colours one mordanting may be sufficient. The mordant is used for successive batches of silk until exhausted; the fresher the mordant, the better for brighter colours. Silk should be dyed as soon after it is dried as is convenient. Another Alum mordant. Dissolve 25 per cent of Alum in hot water and add 6 per cent carbonate of soda crystals. Fill up a jar with water and steep silk in it over-night. It must be washed before dyeing. RECIPES FOR DYEING (1) INDIGO VAT FOR BLUE Silk is dyed in a similar manner as described for wool, but requires stronger vats and longer dips to obtain the same depth of colour. See page 33. (2) INDIGO EXTRACT FOR BLUE Dye at a temperature of 40 to 50 deg.C. with as much Indigo Extract dissolved in the bath as is required for the desired depth of shade. If the silk has been first mordanted with alum, compound colours can be obtained by the addition of a red or yellow dye to the bath. (3) CRIMSON Mordant with Alum or Aluminium Acetate and dye with 40 to 50 per cent Cochineal. A teaspoonful of Tin, dissolved in cold water, may be added to brighten. Boil well. It is advisable to wash in soap after using tin as it prevents the latter making the yarn brittle. (4) MADDER RED Mordant with Alum or Aluminium Acetate. Dye with 80 to 100 per cent Madder and a handful of bran per pound of silk. Bring slowly to the boil in 1 hour, boil a few minutes. It should be brightened by boiling a short time in soap, with a little tin. (5) YELLOW Mordant with Alum or Aluminium Acetate. Various Dyes may be used. _Weld_: Dye with 150 per cent. _Flavin_: Dye with 1 oz. to the pound, with a teaspoonful Tin. _Fustic_: Dye with 50 per cent, or more. _Quercitron_: Dye with 10 to 20 per cent. A little chalk may be added towards the end. The shades may be varied by the addition of small quantities of madder or cochineal. Orange may be obtained by the use of Madder, 2 to 4 ozs. per pound, with Flavin or Fustic. (6) GREEN