1869.] Cryolite. 577 waste products of combustion) through the solution, for the production of car- bonate of soda, and for the precipitation of the alumina in the form of a gelatin- ous insoluble mass, readily separated by filtration. The supplementary stages are the production of caustic alkali, of the bi- carbonate of soda, and of soda crystals, essentialby the same as in Le Blanc's process, as now worked in England. The terms " Soda Ash," and " Soda Crystals," are by no means to be con- founded. The first is applied to the anhydrous mass obtained bj r the evapo- ration, calcination and carbonating of the liquid from the lixiviation of the " Black Ball," or " Black Ash," in Le Blanc's process. It is an impure car- bonate of soda, free from water, and non-crystalline. The second term, "Soda Ciwstals," is sjmonymous with '• Sal Soda ;" and is applied to the pro- duct obtained by dissolving the " Soda Ash" in water, and evaporating the so- lution to the crystallizing point. The salt thus formed contains water of crys- talization, amounting to about 63 per cent, of the whole weight. Sal Soda is the " Washing Soda" of the shops. Bi- carbonate Soda has one atom of water and one extra atom of carbonic acid, in combination with the ordinary or neu- tral carbonate of soda. It is obtained by exposing " Soda Crystals" to the action of carbonic acid gas. This sub- stance is the ordinary "baking soda," or " Super-Carbonate" of the shops. The amount of manipulation, and, therefore, the main item of the cost, is largely in favor of the Cryolite process, as well as the amount of original outlay required for the establishment of soda works. With duty removed from Cry- olite, Soda Ash can be produced in the United States at less cost, and sold to the consumer at lower rates, than the im- ported article. With an onerous duty, or tariff, on Cryolite we must send to England annually for 50,000 tons of Soda, at an enhanced cost ; a direct tax, thence, is laid on at least two important manufietures, Glass and Soap. The fostering of the trade in Cryolite — at present the only raw material, consumed in the United States, for the manufac- ture of Soda — is the erection of a solid, substantial and important branch of industry — which has already done so much for English prosperit}^— and our release from a heavy tribute to foreign manufactures. From the remaining alumina of the Cryolite works is now manufactured a substitute for alum, in the shape of sul- phate of alumina, by which the dyer and paper manufacturer are exempted from paying for two expensive compounds — potash and ammonia — useless to them, but, hitherto, essential to the compo- sition of alum, and to the production of an alumina salt free from noticeable amounts of oxide of iron. The sulphate of alumina now manufactured from the alumina residue is pure, and more val- uable for technical purposes, and is sold at less cost than potash or ammonia alums. It is coming largely into use, in supplanting these expensive and trou- blesome salts, and has already become an article of export to European coun- tries. Without Cryolite, pure sulphate of alumina is a technical impossibility. The employment of these heretofore waste materials of the Cryolite process reduces the cost of the main article of manufacture, whilst a direct benefit is conferred on important industrial branches. The mineral Cryolite is now also em- ployed as a source of the metal alumin- ium. In France, at Amfreville, near Rouen, the Messrs. Tissier are using it with perfect success, dispensing thereby with the troublesome and costby process of a preliminary manufacture of the double chloride of aluminium and so- dium — a chemical equivalent of the na- tive double fluoride of aluminium and sodium, or Crj^olite. It is also success- fully used, in small quantity, in this country, for the same purpose. But it
