vinegar, in a silver spoon; if sulphuretted hydrogen is disengaged, which blackens the spoon, the presence of a sulphate (plaster) will be shown. This adulteration has lately become very common among the paper-makers, with the view of increasing the weight. Waxed Paper.

Take cartridge or other paper, place it on a hot iron and rub it with beeswax, or make a solution of the wax in turpentine, and apply it with a brush. Useful for making water or air-proof pipes, for chemical experiments, &c.

To extract Grease Spots from Paper.

Apply a little powdered pipe-clay, on which place a sheet of paper, then use a hot iron. Remove the adhering powder with a piece of India-rubber.

Papier Mâché,

Take paper, any quantity. Boil it well, then pound it to a paste, and mould. Used in making toys, snuff-boxes, &c.

To Gild the Edges of Paper.

Armenian bole 4 parts; sugar candy 1 part. White of egg to mix. Apply this composition to the edge of the leaves, previously firmly screwed in the cutting-press; when nearly dry smooth the surface with the burnisher; then take a damp sponge and pass over it, and with a piece of cotton-wool take the leaf from the cushion and apply it to the work; when quite dry burnish, observing to place a piece of silver or India paper between the gold and the agate.

Tracing Paper.

Nut oil 4 parts; turpentine 5 parts. Mix, and apply it to the paper, then rub it dry with wheat flour, and brush it over with oxgall. This will bear writing on.

Lithographic Paper.

Give the paper 3 coats of thin size, 1 of starch, and 1 of solution of gamboge. Each to be applied with a sponge, and allowed tó dry before the next is applied.

Hydrographic Paper.

This name has been given to paper which may be written on with water. It may be made by rubbing paper over with a mixture of finely powdered galls and sulphate of iron heated till it becomes white. The powder may be pressed into the paper by passing it between rollers, or passing a heavy iron over it. A mixture of dried sulphate of iron and ferro-prussiate of potash may be used for blue writing. Or the paper may be imbued with a strong solution of one ingredient thoroughly dried, and the other applied in powder. Paper which has been wet with a solution of ferro

prussiate of potash also serves for writing on with a colorless solution of persulphate of iron.

Iridescent Paper.

Nut-galls 8 parts; sulphate of iron 5; sal-ammoniac 1; sulphate of indigo 1; gum-arabic. To be boiled in water, and the paper washed with it exposed to ammonia.

To give Paper the Appearance and Toughness of Parchment. Dip white unsized paper for half a minute in strong sulphuric acid, and afterwards in water containing a little ammonia. dried it will look like, and be as strong as parchment.

Photographic Papers.

When

The following papers should be the finest satin post, of uniform texture, free from the maker's mark, specks, and all imperfections. The papers must be prepared by candle-light, and kept in the dark till used.

1. Simple Nitrated Paper.-This is merely paper brushed over with a strong solution of nitrate of silver. In brushing over the paper it must be crossed. Its sensitiveness is increased by using spirit of wine instead of water. This paper only requires washing in water to fix the drawing.

2. Muriated Paper. The paper is first soaked in solution of copper salt, pressed with a linen cloth or blotting paper, and dried. It is then brushed over on one side (which should be marked near the edge) with the solution of nitrate of silver, and dried at the fire. The stronger the solution the more sensitive the paper. If dipped in a solution consisting of 35 grains of chloride of barium and 2 oz. of distilled water, richer shades of color are obtained.

3. Iodized Paper.-Brush over the paper on one side (which should be marked) with strong solution of nitrate of silver (100 gr. to 1 oz); then dip it in a solution consisting of 100 gr. of iodide of potassium dissolved in 4 oz. of distilled water. Wash it in distilled water, drain, and dry it.

4. Bromide Paper.-Soak the paper in a solution composed of 40 gr. bromide of potassium dissolved in 1 oz. of distilled water; then brush it over with a strong solution of nitrate of silver, and dry in the dark.

5. Calotype Paper.-Dissolve 100 gr. of crystallized nitrate of silver in 2 oz. of distilled water, and add 2 fluid dr. and 40 mínims of acetic acid. Mix these at the time of using with an equal measure of cold saturated recently prepared solution of gallic acid. Brush iodized paper with this solution, and mark the side; in half a minute dip it into water, and press it between blotting paper. It is then ready for the camera, where it remains from half a minute to 5 minutes. When removed from the camera dip it into water,

press it between blotting paper, and wash it with a solution of 100 gr. of bromide of potassium in 8 or 10 oz. of water.

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6. Chromotype Paper.-Soak the paper in a solution of bichromate of potash (in which solution a little sulphate of indigo is sometimes added to vary the color), and dry it at a brisk fire. To fix the drawing careful immersion in warm water is all that is required. It is not sufficiently sensitive for the camera.

7. Compound Chromotype Paper.-Dissolve 10 gr. of bichromate of potash, and 20 gr. of sulphate of copper, in an ounce of water. Wash the paper in this solution, and dry it. After the paper has been exposed to the sun, with the article to be copied superposed upon it, it is washed over in the dark with a solution of nitrate of silver of moderate strength. A vivid picture makes its appearance, which is sufficiently fixed by washing in pure water. This is for copying engravings, &c. Another method is to brush writing paper over with a solution of 1 dr. of sulphate of copper in 1 oz. of water; and when dry with a strong, but not saturated, solution of bichromate of potash.

8. Cyanotype Paper.-Brush the paper over with a solution of ammonio-citrate of iron. Expose the paper in the usual way, then wash it over with a solution of ferro-cyanide of potassium.

9. Crysotype Paper.-Wash the paper with solution of ammoniocitrate of iron, dry it, and afterwards brush it over with a solution. of ferro-cyanide of potassium. Dry it in a dark room. The image is brought out by brushing it over with a neutral solution of gold or silver.

:

10. Catalisotype.-Steep paper in water, with a drop or two of hydrochloric acid; absorb the superfluous moisture with blotting paper; brush over with a mixture of dr. syrup of iodide of iron, 24 dr. of water, and a drop or two of tincture of iodine. Dry with blotting paper, and brush over with a solution of 12 gr. of nitrate of silver to 1 oz. of distilled water. It is then ready for the camera. The picture is fixed by washing in water, and afterwards in a solution of 20 gr. of bromide to 1 oz. of potassium.

11. Paper for Positive Photographs.-Most of the preceding give negative pictures, the lights and shadows being reversed; in the! following they are correct: Dissolve 40 gr. of muriate of ammonia in 4 oz. of water. Wash highly glazed paper in this solution, dry it, and brush it over with the following solution: Dissolve 120 gr. of crystallized nitrate of silver in 1 oz. of distilled water; and add 14 oz. of alcohol; after it has stood a few hours filter it. Expose the paper thus washed to the sunshine, till it is darkened; if mottled, wash it a second time, and expose it again. Before using the paper make up the following solution; Hydriodate of barytes 40 gr.; water 1 oz.; pure sulphate of iron 5 gr. Mix, filter, add a drop or two of diluted sulphuric acid, and when settled decant the clear liquor for use. Wash the paper over in this solution, expose

it in the damp state, with the engraving or other object on it to the light, and fix the drawing by washing with water only.

Photographs.

1

To copy objects, lay them on a plate of clear glass, fixed in a frame; place the prepared paper over them; and fix a back, with a cushion attached to it, so as to press the paper closely on the glass. The glass is then exposed to the light, and the drawing afterwards fixed, as described above. For feathers, lace-work, and other objects which freely admit light through them, the nitrated paper and less sensitive muriated papers may be used. For copying engravings, leaves, and other botanical objects, or entomological specimens, the more sensitive muriated papers, or the bromide paper, or other sensitive kinds, may be used. Engravings should be wetted, and placed with their face to the prepared side of the paper, and kept in close contact with it. Leaves should have their under surface next the glass. For the camera, the most sensitive samples of the muriated papers, made with not less than 100 gr. of nitrate of silver to the ounce, are selected. The calotype is still more certain. The papers intended for the camera require to be very carefully prepared. Glass is used instead of paper, after being coated with white of egg, or collodion, with which the compounds of silver are mixed, or over which they are brushed.

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BRONZING.

Bronzing Sculpture, Wood, &c.

Bronze of a good quality acquires, by oxidation, a fine green tint, called patina antiqua. Corinthian brass receives, in this way, a beautiful clear green color. This appearance is imitated by an artificial process, called bronzing. A solution of sal-ammoniac and salt of sorrel in vinegar is used for bronzing metals. Any number of layers may be applied, and the shade becomes deeper in proportion to the number applied. For bronzing sculptures of wood, plaster figures, &c., a composition of yellow ochre, Prussian blue, and lamp-black, dissolved in glue-water, is employed.

Bronze.

1. Copper 83 parts; zinc 11 parts; tin 4 parts; lead 2 parts. Mix.

2. Copper 14 parts; melt, and add zinc 6 parts; tin 4 parts.

Ancient Bronze.

Copper 100 parts; lead and tin each 7 parts. Mix.

To give an Antique Appearance to Bronze Figures.

Salt of sorrel 1 part; sal ammoniac 4 parts; white vinegar 224 parts. Dissolve, and apply with a camel-hair pencil, just sufficient to damp the bronze, previously warmed. Repeat the operation if required.

Keller's Bronze.

Copper 91 parts; tin 2 parts; zine 6 parts; lead 1 part. Mix. Bronze Powder.

Bichloride of mercury 1 part; borax and nitre each 8 parts tutty 16 parts; verdigris 32 parts; oil to make into a paste. Melt. Beautiful Red Bronze Powder.

Sulphate of copper 100 parts; carbonate of soda 60 parts. Apply heat until they unite into a mass, then cool, powder, and add copper filings 15 parts. Well mix, and keep them at a white heat for twenty minutes, then cool, powder, and wash and dry.

Bronzing Fluid for Guns, &c.

Nitric acid sp. gr. 1.2, nitric ether, alcohol, muriate of iron, each 1 part. Mix, then add sulphate of copper 2 parts; dissolved in water 10 parts.

ENAMELS.

White Enamel.

Tin 2 parts; lead 1 part. Calcine, then take of the above oxides 1 part; crystal 2 parts; manganese a small portion. Grind well together, fuse, and pour the mass into cold water; dry, grind again to powder, and fuse; repeat the process four or five times, observing great care to prevent any contamination from smoke, or iron, or copper.

Another.

Arsenic 14 parts; potash 25 parts; nitre 12 parts; glass 13 parts; flint 5 parts; litharge 3 parts.

Blue Enamel.

Fine paste (not metallic) 10 parts; nitre 3 parts. Oxide of cobalt to color.

Green Enamel.

Frit 1 pound; oxide of copper ounce; red oxide of iron 12 grains.