{1) Enamelling inside of Iron Saucepans. - The article is first cleansed from all oxides by placing it in an acid solution, then dried, after scouring with sand to a grey colour, which shows it to be perfectly clean; apply a solution of gum - arabic to the surface, and sift over it a vitreous substance reduced to fine powder, composed of flint glass, soda carbonate, and boracic acid; then heat it to redness by degrees, till the glass is melted upon the surface. It is then allowed to cool gradually (excluded from the air as much as possible) to anneal it. The glaze is made of 130 parts glass, 20 1/2 soda carbonate, and 12 boracic acid, melted in a crucible, cooled, and then reduced to an impalpable powder. (R. W. Hale.)

(2) For Castings

Consists in treating the casting with dilute hydrochloric acid, which dissolves a little of the metal, and leaves a skin of homogeneous graphite holding well to the iron. The article is then washed in a receiver with hot or cold water, or cooked in steam, so as to remove completely the iron chloride that has been formed. Finally, the piece is allowed to dry in the empty receiver, and a solution of indiarubber or guttapercha, in essence of petroleum, is injected, and the solvent, afterwards evaporating, leaves a hard and 'solid enamel on the surface of the iron - work. Another plan is to keep the chloride of iron on the metal instead of washing it off, and to plunge the piece into a bath of soda silicate and borate. Thus is formed a silico-borate of iron, very hard and brilliant, which fills the pores of the metal skin. As for the chlorine disengaged, it combines with the soda to form sodium chloride, which remains in the pickle. {Lea Mondes.)

(3) For cast - iron pipes. There are various recipes for the enamel, depending on the purpose for which it is applied. One for water pipes is as follows: 28 parts by weight of silica, 11 calcined soda carbonate, and 6 lime carbonate. Another is : 34 silica, 11 soda carbonate, 12 chalk, and 11 dried pipe - clay, to which boracic acid or lead oxide can be added when a more vitreous enamel is required. The core forming the inner surface of the pipe - and, if desirable, the mould too - is coated with graphite (blacklead), smoothed, and the enamel, as a powder, paste, or pigment, is applied to the thickness required. The molten iron causes the enamel to soften and firmly adhere to the iron. If it is not necessary that the enamel should not be smooth, the blacklead is omitted. The enamelled pipes are much appreciated in Bohemia; the Municipal Council of Egar have passed a resolution to use no other kind. They are now being manufactured in several works in Germany and Austria. (Bag and Broz.)

(4) For Culinary Vessels

For enamelling cast - and wrought - iron vessels, the following are the method and materials most generally employed: 100 lb. calcined and ground flints, and 50 lb. borax, calcined and finely ground, are intimately mixed, fused, and gradually cooled. Of this, 40 lb. are mixed with 5 lb. potters' clay, and ground in water to a pasty mass. The vessel, first thoroughly cleansed by means of very dilute sulphuric acid and scouring with sand, is lined with a coating of this about 1/6 in. thick, and left for it to harden in a warm room. A new coating is next added, prepared from 125 lb. white glass free from lead, 25 lb. borax, 20 lb. soda in crystals, which have been pulverized and fused together, ground, cooled in water, and dried. To 45 lb. of this, 1 lb. soda is added; the whole is mixed in hot water, dried, and finely powdered. A portion of this is sifted over the other coating while it is still moist, and the vessel is then dried in an oven at the temperature of boiling water, 212° F. (100° C.) The vessel is heated in a stove or muffle till the glage appears. It is then taken oat, and more glaze powder is dusted on the glazed surface already in fusion.

This enamel resists perfectly the action of dilute mineral and vegetable acids, as well as alkalies, and does not crack or scale off from the metal.

(5) Coloured

The ordinary grey enamel (so called) is really not an enamel, but a transparent glaze, the apparent grey colour of which is produced by the surface of iron beneath the glaze.

(6) For Wall - Plates

Thin sheet - iron is first cut and stamped to the desired shape, the edges of the plate being turned up slightly in the usual way so as to form a shallow tray, the edges serving to hold the enamel in position during the preliminary stages of the process. The plate is then made chemically clean by any of the ordinary processes of pickling and scouring. The ingredients of the enamel should be taken in the following proportions: - White - lead, 12 oz.; arsenic, 2 1/2 oz.; flint - glass, 8 oz.; saltpetre, 3 oz.; borax, 6 3/4 oz., and ground flint, 2 oz. These are powdered, mixed thoroughly, placed in the crucible, and fused; but before they are cooled, they must be plunged into cold water, which has the effect of rendering the mass very brittle. The cakes of fused enamel are then pounded to about the fineness of coarse sand, washed, and dried. The powder is now ready for use. The plates of sheet - iron, having been well cleansed and thoroughly dried, are sprinkled over with sufficient enamel powder to make the coating of the desired thickness, and are then placed in a muffle, the turned - up edges retaining the swelling enamel in position.

Lettering or designs can be produced on the surface by the ordinary means; but if it is desired to put them on when the enamelled plate is cold, they are first received on paper, an impression being taken in soft black enamel from the engraved plate, and subsequently transferred, the article being again placed in the muffle to fuse the enamel of the design or letters. The iron back is more durable than copper, and cheaper. Variations in the colour of the enamel can be obtained by the addition of various salts and earths, such as cobalt, manganese peroxide, iron protoxide, etc, and similar diversity of colour can be introduced, into the design or the letters. (F. Edwards & Son.)