~The Acetate Process.~--Quite recently numerous experiments have been carried out with the object of finding methods for employing the cellulose esters of organic acids in the preparation of fabrics. The acetate, which is generally used, gives solutions from which fibres can be obtained which are comparable to natural silk in strength, and which have the further advantage of being non-inflammable, and far less readily affected by water than artificial fabrics obtained by the above methods. It is prepared by treating cellulose with dilute acid, by which the so-called ‘hydrocellulose’ is obtained; this is treated with a mixture of glacial acetic acid and acetyl chloride, and the whole, after addition of a little concentrated sulphuric acid, warmed to 65°-70°C. As early as 1894, Cross and Bevan[531] had patented a process for this preparation by the action of acetyl chloride in the cold on an intimate mixture of cellulose and zinc chloride. [531] _E._ 9676, 1894. From the solution obtained, the acetates are precipitated by water, washed and dried. The mixture of esters dissolves in chloroform, nitromethane, acetic acid, phenol, pyridine, etc., and is re-precipitated by addition of alcohol, benzene, or ligroin (petroleum ether). On account of its non-inflammable character, cellulose acetate, as the product is called, is being used instead of the nitrate in the manufacture of celluloid; it is also used for non-inflammable cinematograph films. Fibres can be obtained by forcing the solutions through jets, and removing the solvent, as in the above processes; these are spun into threads which are coming into increasing use, on account of their extremely low conducting power, for the insulation of very fine electric leads. The product is at present too expensive, however, for use in the textile industries, or for the manufacture of mantles. A solvent which had at one time some technical importance is zinc chloride.[532] The concentrated aqueous solution of the salt will take up cellulose in considerable quantity; and the solution has been used in the preparation of carbon filaments for glow lamps. [532] Gulbrandsen, _Prog. Age_, 1912, ~30~, 77; Wynne and Powell, _E._ 16805, December, 1884.