MORDANTS.

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eminently beautiful. This property of antimony, which was then no novelty,was claimed by F. A. Gatty, in a patent obtained in 1856. He applies the salts ofantimony, preferably the chloride, for the purpose of precipitating the colouringmatters of dye-materials, such as sapan wood, logwood, cochineal, quercitron,&c., thereby producing colours called lakes, for the manufadture of which othermetallic salts have hitherto been used. To 1 gallon of chloride of antimony,of 80° Tw., he adds 20 gallons of well-aged sapan or Lima-wood liquor, at7° Tw.; the whole is then well stirred and left to stand for a few hours, andthen is put on a filter. When the liquor has run off he adds 4 gallons ofwater to wash the precipitate. The washing is repeated a second time.When the water is drained off the lake is finished, and may either be dried orused in the wet state. The shade of the lake may be varied from a crimsonto more of a scarlet, by using more or less of the chloride. For “ purple orviolet lakes ” logwood is substituted for the sapan wood, and bark-liquor foryellows.

The practical difficulty in this process is that the chloride of antimony isprecipitated by water alone as decidedly as by solutions of colouring matters.Hence it follows that, in addition to the true antimonial lake, a variable quan-tity of antimonic oxychloride (salt of algaroth) is thrown down, which dilutesand “ flattens ” the colour of the lake. To prevent this an addition of tar-taric acid would be necessary, previous to mixing the antimony solution withthe sapan liquor.

Bismuth Mordants.

Bismuth presents certain analogies with tin, which have led to the opinionthat it might be valuable as a mordant. It possesses a strong affinity forcolouring matters, and with proper precautions it gives rise to a variety ofbeautiful lakes. On the other hand, its affinity for animal and vegetable fibresis less decided than that of tin. Its acid solutions, on dilution with water,are decomposed too readily, the bulk of the bismuth being thrown down, inthe state of an insoluble sub-salt, without the application of heat, and withoutthe presence of any organic fibre or tissue. This evil can be to some extentprevented by the addition of acetic acid, but the shades produced, as far asour present experience goes, though rich and brilliant, are deficient in evennessand solidity.

In 1855 E. Kopp took out an English patent for the use of the aceto-nitrateof bismuth as a “ mordant for garancin colours.” This salt was to be pre-pared by dissolving as much bismuth as possible in hot nitric acid (strengthand temperature not stated), diluted with half its weight of water. Oncooling, yellowish crystals are deposited, which, dissolved in acetic acid at8° Tw., constitute the improved mordant. According to the inventor, thisaceto-nitrate of bismuth gives, with garancin, peculiar bright crimsons, and,when mixed with a solution of arseniate of iron in nitric acid, it produces,with the same dye-ware, peculiar dark crimson and purple-crimson shades.Prior to this date all the easily-prepared preparations of bismuth had beentried in England, by C. O’Neill and others, without any valuable results. Thespecification above quoted, after careful and repeated trials, yielded nothingof any commercial value. Mr. O’Neill, who had an opportunity of examiningthe patentees’ original patterns, pronounces them no better than those obtainedin this country.