186

Class 2.— CHEMICAL AND PHARMACEUTICAL PRODUCTS.South Gat,t,key.

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Crystals of Sulphate of Iron.

The forms of the crystals of sulphate of iron are repre-sented in the above cuts.

Schale, or schist, found overlying and underlying allthe coal veins, and brought up in immense quantities innearly all the coal workings, and also in the ironstonemining, the nodules of ironstone being imbedded in theshale. By a patent process, its own weight of alum canbe produced, by acting on it with sulphuric acid, &c., oneton of shale, of average quality, yielding one ton of alum.

Shale, calcined for the manufacture of alum.

Shale in the process or manufacture of alum.

Alum of the first and second crystallization.

Alum finished for the market.

Patent zinc cement, or hydraulic mortar.

Specimens of the waste materials from which thecement is manufactured.

Bust composed of the cement.

The cement laid on to wall. Manufactured entirelyfrom refuse matters.

The refuse shale, after the patent alum process, affordsthe silica and alumina; the refuse lime, after purifyinggas for illumination, affords the calcareous ingredient j andthe metallic constituent, zinc, is obtained as sulphateof zinc from the refuse of Wicklow pyrites, after itsuse in the manufacture of sulphuric acid. The cementis hydraulic; the affinity of oxide of zinc for oxygenprevents the oxidization of any iron, and its deleterious

effect on vegetation prevents the growth of moss on itsurface.

[Iron pyrites may he made to yield at least two valu-able chemical products, sulphur, and sulphate of iron, orcopperas. The first is obtained by heat, sulphate of ironby simply exposing the iron pyrites, which is a bisulpliuretof iron, to the weather. The mass absorbs oxygen from theair, a sulphate of iron is formed, and is washed out andcrystallized. The shale or schist employed in the alummanufacture is a slaty clay found both overlying andunderlying coal strata, and containing much pyrites.—R. E.]

7a Tennaxts, Clow, & Co., Manchester —Manufacturers.

Sulphate of copper. Sulphate of zinc. Muriate of tinin crystals. Bichloride of tin. Nitrate of lead. Bichro-mate of potash. Prussiate of potash. Prussiate (red).Chlorate of potash. Garancine. Stannate of soda. Bi-sulphate of potash. Soda-ash. Sal-ammoniac; and pinksalt.

[The compounds here exhibited furnish a remarkableillustration of the extensive applications of chemistry tomodern arts and manufactures. The series exhibited