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DYEING AND CALICO PRINTING.

also been produced by a totally different process. Solutions of the moreeasily reducible metals, such as silver, lead, tin, bismuth, &c., free from excessof acid, were mixed with suitable reducing agents, such as aldehyde, methylicspirit, and thickened with glucose. This mixture being printed upon thefabric, a pattern was brought out in reduced metal. The ease with whichsuch delicate metallic films were adted on by sulphurous fumes present in theatmosphere caused the goods soon to become very unsightly, as the processis, for the present, in abeyance. It so happens that with the exception ofgold, which is too costly for articles of common consumption, the more,readily reducible metals have all a strong affinity for sulphur, by which theyare blackened. A practicable method of depositing, e.g., aluminium uponsilk or worsted goods, would be of great value.

RED MINERAL PIGMENTS.

Of red pigments minerals yield—one iodide, that of mercury; three sul-phides, viz., cinnabar or Vermillion, the sulphide of mercury,—antimonialVermillion, the tersulphuret of antimony,—and realgar, or the bisulphide ofarsenic. Among the oxides and derivatives we have—red-lead, or minium, apeculiar oxide of lead; English red peroxide of iron, red ochre; suboxide ofcopper ; the red oxide of tin, a modification of oxide of tin ; purple of Cassius ;chromates of mercury and silver; and subchromate of lead. None of theseor any other red mineral pigments are suitable for use on the large scale,owing to their high price, and in some instances to the fadt that they have agreat tendency to subside from the fluid in which they are suspended.

Bi-iodide of mercury yields a very rich scarlet, easily formed by the unionof iodine and mercury, or by double decomposition between a soluble iodideand a solution of corrosive sublimate. 200 grms. of mercury are trituratedwith 254 grms. of iodine, with the addition of a little alcohol; or a solution ofcorrosive sublimate is precipitated with iodide of potassium, or, moreeconomically, with iodide of iron produced by the adtion of iron on iodine inthe presence of water.

The fixation of the colouring matter upon cotton tissues is a simpleoperation, but as the colour is very fugitive it is in very little request.

Cinnabar, vermillion, or sulphide of mercury, is formed artificially by a dryor wet process, but a cinnabar which occurred native was known in Pliny’stime by the term minium. In the former process, 540 parts of mercury and75 parts of sulphur are intimately combined to form a black powder, which isintroduced into iron vessels, and exposed to sufficient heat to fuse the mass.The fused mass, when cool, is broken up, and introduced into loosely-coveredearthenware vessels, heated on sand-baths ; when sublimed the mass is pul-verised, the result being a powder of a cochineal-red colour. Vermillion isobtained by the wet process, by precipitating a solution of corrosive sublimatein ammonia with a solution of sulphur in sulphide of ammonium ; or, accordingto Dr. Von Martius, by agitating 1 part of sulphur, 7 parts of mercury, and 2to 3 parts of a concentrated solution of liver of sulphur. M. Brunner pre-pares a vermillion of the highest order of brilliancy by mixing 114 parts byweight of sulphur and 300 parts by weight of mercury, with the addition of asmall quantity of caustic potash solution. This mixture is then treated witha solution of 75 parts caustic potassa in 400 parts of water, and heated on a