and, when it comes from the mill, add 135 parts of lead. Stain to the above, 10 parts of glass, and 5 oz. of blue.

To prepare white enamel.

Take 7 oz. of arsenic, 12 do. potash, 6 do. nitre, 5 do. glass, 2 do. flint, and 3 do. white lead. To prepare china glaze.

Take 56 parts of stone, 46 do. borax, 18 do. glass, 15 do. flint, and 40 do. lead.

To prepare green edge glaze.

Take 20 parts of lead, 60 do. stone, 20 do. flint, and 10 do. ground glass.

To prepare materials for common ware. Take 25 parts of flint, 60 do. store, 95 do. lead,

and 8 do. frit.

To prepare glaze for green edge. Take 175 parts of lead, 100 do. stone, and 35 do. flint.

To prepare fluxes for blue printing. Take 5 parts of blue calx, 5 do. coak stone, 13 do. glass, and 1 do. flint.

To prepare flux for black printing.

To form a cane body.

Take 4 parts black marl, 2 do. Cornish stone and 1 do. cream-coloured clay.

To form a jasper body.

Take 3 parts coke stone, 2 do. Cornish do. do. blue clay, do. flint, and 1 dr. blue calx. To form a drab body.

Take 2 parts blue clay, 1 do. Čhina do. 3 dr, composition,do. Bradwell wood clay. To form a pearl body.

Take 6 parts Cornish stone, 2 do. Derbyshire clay, 1 do. flux. FLUX, 8 parts glass, 24 do. redlead. To form a stone body.

Take 2 parts blue clay, 2 do. china do. 4 do. composition.

To form an Egyptian black body. Take blue clay, 30 parts, black mari, 5 do. ealcined car, 25 do. manganese, 2 do.

To form a china body.

Take blue elay, 12 parts, china do. 6 do. bone, 12 do. Cornisu stone, 12 do. flint, 6 do. flint glass

To prepare red flux.

Common glazing for earthen ware. Take of white sand, 40 lbs. red lead, 20 lbs.

To prepare black.

the sand by grinding before it be mixed with the other ingredients, and then grind them together, after which, calcine them for some time with a moderate heat, which must be less than will make them melt and run to glass; and when the mixture is cold, grind it to powder again, and, when wanted, temper it with water, and it will then be fit for use.

The proportions of these ingredients may be varied occasionally, for, where the glazing can be fluxed conveniently with a very strong fire, the quantity of sand may be increased to 60 or 70 lbs. which not only renders the glazing stronger, but makes a saving in the expense. The proportion of pearl-ashes may likewise be diminished, or they may be wholly omitted where the ware is designed for very coarse purposes, and not for domestic uses, where the lead is very improper, being extremely apt to be corroded by acids, and to produce a very unwholesome substance. On this ac

To prepare oil for black printing. Take half a pint of linseed oil, boiled well until of a proper consistence, to which add a small quantity of Barbadoes tar, prepared the same way.

Another.

the lead ought to be excluded from the composition of the glazings, and other fluxes used in its stead, as in the following:

Transparent glazing for earthenware. Take of white sand, 40 lbs. of pearl-ashes, 21 lbs. and of common salt, 15 lbs. Caleine, and proceed

Where the expense is no object, this glazing may be improved by adding one or two pounds of bo rax, and diminishing the pearl-ashes, in the proportion of six pounds for one pound of borax ad¦ded, or ten pounds for two; in the latter case, twe

To form a blue printing body.

sition. The reason for this change is, that if the composition contain so large a proportion of salt,

it is laid on the ware, it will be apt to be dissolved by boiling water, and peel off, if it be exposed to ; the action of it for any long time.

Another.

Take of sand, 40 lbs. of wood ashes, perfectly burnt, 50 lbs. of pearl-ashes, 10 lbs. of common salt, 12lbs.

This will make an admirable glazing, where the ashes are pure, and a strong fire can be given to fius it when laid on the ware. It will be perfectly free from the imperfection of the above, and will be very hard and glossy, and where the expense i can be afforded, it may be mele more yielding w

Another method of glazing without lead has been invented by a potter at Leipzig: it consists of half a pound of saltpetre, half a pound of potash, and 1 pound of common salt. This composition is not ve.y expensive, and is said to produce an enamel not inferior to that prepared with lead. To apply on every kind of hardware, colours which produce herborisations. Herborisations can be of all colours; but the most agreeable is that called bistre, which is composed in the following manner:

A pound of calcined manganese; 6 oz. of burnt iron straw, or a pound of iron ore; and 3 oz. of flint-powder.

The manganese and straw or iron ore must be pounded separately in a mortar, after which the whole is calcined together in an earthen-pot. This mixture, thus prepared, is all pounded together, and then mixed in a small tub of water.

The blue, green, and other colours must be composed of the divers substances known to produce them, and mixed, calcined, and pounded in the same manner as for the bistres.

To make the application of these various colours to the pieces, it is necessary, instead of diluting them with water, as is practised for ordinary painting, to make use of any kind of mordant. The most advantageous, and which are employed with the greatest success, are urine, and the essence of tobacco.

If the essence of tobacco is made use of, infuse 2 oz. of good tobacco in leaves, during 12 hours, in a bottle of cold water, or very simply infuse the 2 oz. of tobacco in a bottle of hot water.

The pieces of clay, after taking a little consistency, are steeped in white or coloured worm-seed, unt the bath puts them in a state of moisture. To produce herborisations, it will be sufficient, whilst the worm-seed is still fresh, and at the moment when the piece is taken down from the tub, to lay on slightly, and with a brush, one or several drops of other colours: each drop produces a tree more or less great, according as the workman has charged his brush with colours.

To ornament all kinds of glass in imitation of engraving, &c.

The method heretofore known for engraving on glass, has been by means of a machine with wheels, of different substances, which have been employed with sand, &c. to grind off some parts of the surface of the glass which is to be engraved on, and then by means of grinding and polishing different parts on the rough surface, the different figures are formed according to the designs given. By this invention, instead of grinding or taking off any part of the surface of the glass, the patentee lays on an additional surface or coating of glass, prepared for the purpose, which, when subjected to a proper degree of heat, will incorporate with the glass to be operated upon, so as to produce an effect similar to that which has hitherto been obtained by means of grinding. When it is required to ornament glass, then, previously to the heat being applied, with an etching or engraving tool, such parts are to be taken out as will produce the required effect, and that in a much superior way to the effect produced by the usual mode of grind ing, polishing, &c. The materials used are to be melted in a crucible, or other pot, and they are to be made up in the same manner as if used for the making of the best flint glass, broken glass, or, as it is usually denominate, "cullitt," being the principal ingredient in it. Several mixtures are giver, of which the first is, 160 parts of cul

arrence.

The second is, 120 parts of cullitt, 160 of rec lead, 60 of sand, and 60 of borax.

The third is, 70 parts of red lead, 22 of sand, and 410 of calcined borax,

When these are subjected to such a heat as to de thereby completely fused, take equal parts of eacn mixture, and grind them to an impalpable powder, for the purpose of being mixed with a menstruum proper for coating the glass.

The menstruum consists of one part of double refined loaf sugar, dissolved in two parts of pure water: to which is added, at the time of mixing the powder, about one-third part of common writing ink-the effect, we are told, produced by this addition of oxide of manganese, used in a small quantity by the glass-makers, in making their best flint-glass, because without such an addition the specimens would be of a cloudy or milky appearance. A quantity of this menstruum is used suthicient to render the ground-mixture of a proper consistence for laying on with a thin smooth surface. When the coating or mixture is thus pre pared, the glass is to be coated by means of a camel's hair brush, or squirrel's foot, &c. It is ther. to be exposed to a heat sufficient to produce a semivitrification of the coaty surface, and to incorporate it with the substance or body of glass so coated. But the heat must not be carried higher than this. because, in that case, a complete vitrification would ensue, and the desired effect of having a surface in imitation of the rough surface produce> by grinding, would not be obtained: the article must, under such circumstances, be re-coated, and submitted again to the fire. If, after the coating has been applied, any borders, cyphers, or othe: ornaments, are wanted to be executed thereon then, previously to the heat being applied with an etching or engraving tool, such parts of the coated surface must be chased out, as will produce the desired effect, after which the requisite degree of heat is to be applied.

This invention is not only applicable to al. kinds of useful and ornamental articles of glassware, on which the common methods of engraving have been practised, but may be applied to window glass and plate-glass of every description, ir. place of grinding, for the purpose of making window-blinds. It is also said to be peculiarly adopted to produce beautiful specimens of art, for the windows o altar-pieces, libraries, museums coach-windows, and for the glass used in ornamental buildings of all descriptions. This invention. has another advantage over the common method by the work wearing much cleaner than the work of ground glass; the surface of which being frac tured by the action of the wheel, &c. is therefore liable to gather dirt on the rough unpolished parts of the borders, &c.

To make the Bologna phial.

The Bologna, or philosophical phial, is a smal vessel of glass, which has been suddenly cooled, open at the upper end, and rounded at the bottom It is made so thick at the bottom, that it will bear a smart blow against a hard body, without break ing; but if a little pebble, or piece of Яint, is !et fall into it, it immediately cranks, and the bottom falls into pieces: but, unless the pebble or flint is large and angular enough to scratch the surface of the glass, it will not break.

To make Prince Rupert's drops. Prince Rupert's drops are inade by letting drops of melted glass fall into cold water; the drop assumes by that means an oval form with a tail o neck resembling a retort. They possess this sin

gular property, that if a small portion of the tail is broken off, the whole bursts into powder, with an explosion, and a considerable shock is communicated to the hat that grasps it.

To break gauss in any required way. Dip a piece of worsted thread in spirits of turpentine, wrap it round the glass in the direction

required to be broken, and then set fire to the thread, or apply a red hot wire round the glass, and if it does not immediately crack, throw cold water on it while the wire remains hot. By this means glass that is broken may often be fashioned and rendered useful for a variety of purposes.

To manufacture glass.

Glass is a combination of sand, flint, spar, or some other silicious substances, with one or other of the fixed alkalies, and in some cases with a metallic oxide. Of the alkalies, soda is commonly preferred; and of the silicious substances, white sand is most in repute at present, as it requires no preparation for coarse goods, while mere washing in water is sufficient for those of a finer quality. The metallic oxide, usually employed, is litharge, or some other preparation of lead, as being the cheapest metal."

The silicious matter should be fused in contact with something called a flux. The substances proper for this purpose are lead, borax, arsenic, nitre, or any alkaline matter. The lead is used in the state of red lead; and the alkalies are soda, pearlashes, sea-salt, and wood-ashes. When red lead is used alone, it gives the glass a yellow cast, and requires the addition of nitre to correct it. Arsenic, in the same manner, if used in excess, is apt to render the glass milky. For a perfectly transparent glass, the pearl-ashes are found much superior to lead; perhaps better than any other flux, except it be borax, which is too expensive to be used, except for experiments, or for the best looking-glasses.

The materials for making glass must first be reduced to powder, which is done in mortars or by horse mills. After sifting out the coarse parts, the proper proportions of si.ex and flux are mixed togetier, and put into the calcining furnace, where they are kept in a moderate heat for 5 or 6 hours, being frequently stirred about during the process. When taken out, the matter is called frit. Frit is easily converted into glass by only pounding it, and vitrifying it in the melting pots of the glass furnace; but in making fine glass, it will sometimes require a small addition of flux to the frit to correct any faut. For, as the flux is the most expensive article, the manufacturer will rather put too little at first than otherwise, as he can remedy this defect in the melting pot. The heat in the furnace must be kept up until the glass is brought to a state of perfect fusion; and during this process any scum which arises must be removed by ladies. When the glass is perfectly melted, the glass-blowers commence their operations.

This requires a long heating to make clear glass, and the heat should be brought on gradually, or the arsenic is in danger of subliming before the fusion commences. A still cheaper composition is made by omitting the arsenic in the foregoing, and substituting common sea-salt.

For the best German crystal glass, take 120 los. of calcined flints or white sand, the best pearlashes, 70 lbs. saltpetre, 10lbs. arsenic, Ib. and 5 oz. of magnesia. Or, a cheaper composition for the same purpose is 120 lbs. of sand or flints, 46 lbs. of pearl-ashes, 7 lbs. of nitre, 6lbs. of arsenic, and 5 oz. of magnesia. This will require a long continuance in the furnace; as do all others where much of the arsenic is employed.

For looking-glass plates, washed white sand, 60 Ibs. purified pearl-ashes, 25 lbs. nitre, 15 lbs. and 7 lbs. of borax. If properly managed, this glass will be colourless. But if it should be tinged by accident, a trifling quantity of arsenic, and an equal quantity of magnesia, will correct it; an ounce of each may be tried first, and the quantity increased if necessary.

The ingredients for the best crown-glass must be prepared in the same manner as for lookingglasses, and mixed in the following proportions: 60 lbs. of white sand, 30 lbs. of pearl-ashes, and 15 lbs. of nitre, 1 lb. of borax, and half a pound of arsenic.

The composition for common green window glass is, 120 lbs. of white sand, 30 lbs. of unpuri fied pearl-ashes, wood-ashes, well burnt and sifted 60 lbs. common salt, 20 lbs. and 5 lbs. of arsenic

Common green bottle-glass is made from 200 lbs. of wood-ashes, and 100 lbs. of sand; or 170 lbs. of ashes, 100 lbs. of sand, and 50 lbs. of the lays of an iron furnace: these materials must be wel mixed.

The materials employed in the manufactory of glass are by chemists reduced to three classes, namely, alkalies, earths, and metallic oxides.

The fixed alkalies may be employed indifferently; but soda is preferred in this cou..try. The soda of commerce is usually mixed with common salt, and combined with carbonic acid. It is proper tu purify it from both of these foreign bodies before using it. This, however, is seldom done.

The earths are silica (the basis of flints), lime, and sometimes a little alumina (the basis of clay) Silica constitutes the basis of glass. It is employ

ture.

For a cheaper flint-glass, take 120 lbs. of white sand, 35 lbs. of pearl-ashes, 40 lbs. of red lead, 13 lbs. of nitre, 6 lbs. of arsenic, and 4 oz. of magnesia.

times, for making very fine glass, rock crystals are

ble, to be perfectly white, for when it is coloured with metallic oxides, the transparency of the glass is injured. Such sand can only be employed for very coarse glasses. It is necessary to free the sand from all the loose earthy particles with which