(1) The hair is left for 12 hours in a solution of 3 parts carbonate of ammonia in 100 water at 86° F. (30° C), then washed, wasned again in soap, and completely scoured with another solution of carbonate of ammonia. The hair is afterwards dipped in the solution of peroxide of hydrogen, which has been completely neutralized with ammonia. The hair is either left in the bath until sufficiently bleached, or it is taken oat, dried by ordinary temperature, and retaken through the bath. To ascertain if the baths have become useless for further work, a few drops of permanganate of potash are added, and if the bath takes a permanent red colour its bleaching power is exhausted. Black hair is not bleached to perfection, it can only be bleached to light gold-yellow. The hair is then washed in water, and can be treated with alcohol. Warm solution and drying in hot air are to be avoided.
(2) A recipe stated to bleach human hair white instead of blonde or yellow. Mix 1 lb. hydrogen peroxide with 1 oz. ammonia; mix 4 oz. hydrogen peroxide with 1 oz. cream of tartar dissolved in 1 oz. soda. Blend the two solutions, and steep 1 lb. of the hair in it for 3 hours. Then wash in clean water with "soapine " in a bath of pottery or clay, and thoroughly dry. Repeat the process 15 or 16 times; but thoroughly mix and shake up the hair after the 12th and every succeeding time. Finally, draw the hair through a solution of blue aniline and alcohol.
(3) A hot dilute solution of nitric acid is most effectual. Brown hair, when carefully treated, is turned the most brilliant golden, resembling golden spun glass. The method employed is to put the hair in a porcelain dish with dilute NO,' HO (about 1 part strong acid to 10 of water), then gradually heat, and, as soon as the required shade is obtained, take out and wash. If the acid is too strong, or the heat too great, the fibre of the hair is spoiled. Dark-brown hair acquires generally a reddish colour, and black hair will turn nearly white.