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bottle-corks consists of pitch hardened | ping a little upon a cold stone you think by the addition of resin and brick-dust. Cement for Ivory, or Motherof-Pearl.-Dissolve I part of isinglass and 2 of white glue in 30 of water, strain and evaporate to 6 parts. Add th part of gum mastic, dissolved in a part of alcohol, add 1 part of zinc white. When required for use, warm and shake up.

Indianite Cement.-1. 100 parts finely-chopped rubber, 15 resin, 10 shellac, dissolved in a sufficient quantity of bisulphide of carbon. Usea for uniting pieces of india-rubber. 2. India-rubber, 15 grs.; chloroform, 2 oz. ; mastic, oz. The two first-named to be mixed, and after the rubber is dissolved add the mastic in powder; allow to macerate for a week.

Cheap India-rubber Cement.

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Cement for Jet.-Shellac is the only cement used by jewellers for jet articles. The broken edges should be made warm before applying the cement. Should the join be in sight, by smoking-Cut virgin or native india-rubber with the shellac before applying it, it will be a wet knife into the thinnest possible rendered the same colour as the jet slices, and with shears divide these into itself. threads as fine as fine yarn. Put a small quantity of the shreds (say or less of the capacity of the bottle) into a wide-mouthed bottle, and fill it three-quarters full with benzine of good quality, perfectly free from oil. The rubber will swell up almost immediately, and in a few days, especially if often shaken, assume the consistence of honey. If it incline to remain in undissolved masses, more benzine must be added; but if too thin and watery it needs more rubber. A piece of solid rubber the size of a walnut will make a pint of the cement.

Cement for Meerschaum.Take some garlic and crush it, in order to form a kind of dough, rub over the broken pieces of Meerschaum with it and reunite them by drawing very closely, bind them with iron wire according to the strength of the pieces, and finally make them boil during half an hour in a sufficient quantity of milk. Or use quicklime mixed to a thick cream with the white of an egg. These cements will also unite glass or china.

Plumber's Cement.-Black resin, 1 part; brick-dust, 2 parts; well incorporated by a melting heat.

Turner's Cement.-1. Take of Burgundy pitch, 2 lbs. ; of resin, 2 lbs.; of yellow wax, 2 oz.; and of dried whiting, 2 lbs.: melt and mix. 2. Black resin, lb.; yellow wax, 1 oz.; melt together, and pour into a tin canister. When wanted for use, chip out as much as will cover the chuck to the th of an inch. spread it over the surface i small pieces, mixing it with an eighth of its bulk of guttapercha in thin slices; then heat an iron to a dull red heat, and hold it over the chuck till the mixture and gutta are melted and liquid; coil the iron a little, and with it stir the cement until it is homogeneous; chuck the work, lay on a weight to enforce contact, leave it at rest for half an hour, when it will be ready for the lathe. 3. Four parts resin melted with 1 part pitch; while these are boiling add brick-dust until by drop

This cement dries in a few minutes, and by using three coats in the usual manner, will unite leather straps, patches, rubber soles, backs of books, &c., with exceeding firmness.

Cement, Elastic.-Bisulphide of carbon, 4 oz.; fine india-rubber in shreds, 1 oz.; isinglass, 2 drachms; gutta-percha, oz.; dissolve. Used for cementing leather or india-rubber. The parts to be joined must be coated thinly with the solution, and allowed a few minutes to dry, then heat to melting; place the parts together and well hammer the air bubbles out.

Cement for Mounting Photographic Prints.- Fine wheat starch, 4 drachms; beat into a paste with cold water 1 oz. of best Russian glue; dissolve in a pint of beefing water; while boiling pour on the starch; put the whole into a saucepan, and boil till as thick as treacle. When required for

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use a small quantity is to be melted in | part of glue in 16 parts of water, and a little warm water.

Cement for Wood Vessels required to be Water-tight. A mixture of lime-clay and oxide of iron separately calcined and reduced to fine powder, then intimately mixed, kept in a close vessel, and mixed with the requisite quantity of water when used.

Cement for Leather.-A good cement for splicing leather for straps is gutta-percha dissolved in bisulphide of carbon, until it is of the thickness of treacle; the parts to be cemented must first be well thinned down, then pour a small quantity of the cement on both ends, spreading it well so as to fill the pores of the leather, warm the parts over a fire for about half a minute, apply them quickly together, and hammer well. The bottle containing the cement should be tightly corked and kept in a cool place.

Marble Cement.-Take plaster of Paris, and soak it in a saturated solution of alum, then bake in an oven, the same as gypsum is baked to make it plaster of Paris; after which grind the mixture to powder. It is then used as wanted, being mixed up with water like plaster and applied. It sets into a very hard composition capable of taking a very high polish, and may be mixed with various colouring minerals to produce a cement of any colour capable of imitating marble. This cement is also used for attaching glass to metal.

Impervious Cement for Apparatus, Corks, &c.-Zinc white, rubbed up with copal varnish to fill up the indentures; when dry, to be covered with the same mass, somewhat thinner; and lastly, with copal varnish alone.

Chinese Cement.-Finest pale orange shellac, broken small, 4 oz.; rectified spirit (the strongest 58 o.p.) 3 oz.; digest together in a corked bottle in a warm place until dissolved; it should have the consistence of treacle. For wood, glass, ivory, jewellery, and all fancy works, used.

Cements for Cracks in Wood. -Make a paste of slacked lime, 1 part; rye meal, 2 parts; with a sufficient quantity of linseed oil. Or, dissolve 1

when almost cool stir in saw-dust and prepared chalk a sufficient quantity. Or, oil-varnish thickened with a mixture of equal parts of white-lead, redlead, litharge, and chalk.

Cements for Joining Metals, or Glass and Wood.-Melt resin and stir in calcined plaster until reduced to a paste, to which add boiled oil a sufficient quantity to bring it to the consistence of honey; apply warm. Or, melt resin 180 parts, and stir in burnt umber, 30; calcined plaster, 15; and boiled oil, 8 parts. Or, dissolve glue in boiling water to the consistence of cabinet-maker's glue, then stir in sufficient wood ashes to produce a varnishlike mixture. While hot, the surfaces to be united must be covered with this compound and pressed together.

Stonemason's Cement.-Clean river sand, 20 lbs. ; litharge, 2 lbs.; quicklime, 1 lb. ; linseed oil, sufficient to form a thin paste. This cement is applied to mend broken pieces of stone, and after a time it becomes exceedingly hard and strong. A similar composition has been used to coat brick walls, under the name of mastic.

Fireproof and Waterproof Cement.-To 4 or 5 parts of clay, thoroughly dried and pulverized, add 2 parts of fine iron filings free from oxide, 1 part of peroxide cf manganese,

part of sea salt, and part of borax. Mingie these thoroughly and render them as fine as possible, then reduce them to a thick paste with the necessary quantity of water, mixing thoroughly well. It must be used immediately After application it should be exposed to heat gradually increasing almost to a white heat. This cement is very hard, and presents complete resistance alike to a red heat and boiling water. Another method:-To equal parts of sifted peroxide of manganese and well-pulverized zinc white, add a sufficient quantity of commercial soluble glass to form a thin paste. This mixture, when used immediately, forms a cement quite equal in hardness and resistance to that obtained by the first method.

Electrical or Chemical Cement.-A good cement for chemical and electrical apparatus may be prepared by mixing 5 lbs. of resin, 1 lb. of wax, 1 lb. of red ochre, and 2 oz. of plaster of Paris, and melting the whole with moderate heat.

Engineers' Cements for Making Joints.-1. Mix ground whitelead with as much finely-powdered redlead as will make it the consistence of soft putty. 2. Mix equal parts of whitelead and red-lead, and add as much boiled linseed oil as is required to give it the proper consistence; or boiled linseed oil and red-lead mixed into a putty. These cements are used for making metallic joints sound.

Iron Cements, or Rust Joints.-1. 1 lb. clean iron borings, pounded fine in a mortar, 2 oz. sal ammoniac in powder, 1 oz. flour of sulphur. The whole mixed by pounding, and to be kept dry. For use, mix 1 part of the above with 20 of iron borings pounded, adding water to the consistence of mortar. 2. 2 lbs. clean iron borings, 1 oz. flour of sulphur, 1 oz. sal ammoniac. 3. 98 parts of fine iron borings through a sieve, 1 flour of sulphur, 1 sal ammoniac. Mix and dissolve in boiling water when required for use. 4. Mix 1 lb. fine borings, oz. sal ammoniac, pounded small, oz. spirits of salts, and a little water. Prepare the joint by bringing the inner joint rings of the flanges together-screwing up the bolts firmly; in this condition there should be an annular space between the flanges of from in. to in. in width; a strand of rope-yarn or any soft fibre should now be stuffed to the bottom of the joint, so as to prevent the jointing material from being driven through in the process of calking. A good hammer, a calking iron rather thinner than the joint, and a flat piece of wood or sheet iron should be in readiness. Take a suitable quantity of fine cast-iron borings, free from dust, and which may be passed through a sieve to remove large pieces; next dissolve a very small piece of sal ammoniac in water, say a drachm to a quart. In the absence of sal ammoniac to mix up the borings

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with, the urine of any animal does quite as well. Now mix the borings with sufficient of the fluid to cause them to adhere together in lumps when com. pressed in the hand. It is now ready for use. By means of the calking iron, and the piece of board or plate, stuff the moist material into the joint to a depth of 1 in. or so from the bottom, all round; now calk it down with the iron and hammer until it sounds perfectly soliu, as though it struck against solid iron. Repeat the process of filling, then the calking, and so on, until the joint is filled to the surface. The joint shoul rest for at least ten hours before being put under pressure.

Cement to Mend Iron Pots and Pans.-Take 2 parts of sulphur, and 1 part, by weight, of fine black-lead; put the sulphur in an old iron pan, holding it over the fire until it begins to melt, then add the lead; stir well until all is mixed and melted; then pour out on an iron plate, or smooth stone. When cool, break into small pieces. A sufficient quantity of this compound being placed upon the crack of the iron pot to be mended, can be soldered by a hot iron in the same way a tinsmith solders his sheets. If there is a small hole in the pot, drive a copper rivet in it and then solder over it with this cement.

London Cement.-Boil a piece of Gloucester cheese three times in water, each time allowing the water to evaporate. Take the paste thus left and thoroughly incorporate with dry quicklime. It will mend glass, wood, china, &c., very effectually.

Architectural

Cement.

Strong rice-water size and paper pulped in boiling water are mixed together; enough whiting is then added to make it of a proper consistence.

Renovating Files.-The file to be first cleansed from all foreign matter, and then dipped in a solution of 1 part nitric acid, 3 parts sulphuric acid, and 7 parts water; the time of immersion will be according to the extent the file has been worn and the fineness of the teeth, varying from 5 seconds to 5 minutes. On taking it out of the mixture, wash in

water, then dip in milk of lime, wash off | the lime, dry by a gentle heat, rub over equal parts of olive oil and turpentine, and finally brush over with powdered

coke.

Galvanic Method. - Well-wora files are first carefully cleaned by means of hot water and soda; then placed in connection with the positive pole of a battery, in a bath composed of 40 parts of sulphuric acid, 80 parts of nitric acid, and 1000 parts of water. The negative pole is formed of a copper spiral surrounding the files, but not touching them; the coil terminates in a wire which rises towards the surface. When the files have been ten minutes in the bath they are taken out, washed, and dried.

Softening Files. ·

Cover them with oil and hold them over the fire until the oil blazes, as soon as the flame runs all over the file, plunge it in the water; or put them in a moderate hot oven for half an hour if large files, but if small the first plan is the best.

Softening Cast Iron.-Heat the metal to a bright red, cool quickly in water, reheat, and then anneal by cooling slowly in ashes. Or, heat the metal to a red heat, let it lie a few minutes until nearly black, and then throw it into soapsuds.

Softening Castings.-Place the castings, surrounded by saw-dust, in an iron box, close it up with clay to exclude the air, and subject it to a red heat for several hours. The castings must be cold before they are withdrawn.

Hardening and Tempering Tools and Metals.-The following is the colour and temperature required:Pale straw, 430° Fah., for lancets, &c.; dark yellow, 470° Fah., for razors, &c. ; dark straw, 470° Fah., for penknives; clay yellow, 490° Fah, for chisels and shears; brown yellow, 500° Fah., for adzes and plane irons; very pale purple, 520° Fah., for table-knives; light purple, 530° Fah., for swords and watchsprings; dark purple, 550° Fah., for softer swords and watch-springs; dark blue, 570° Fah., for small fine saws; blue, 590° Fah., for large saws; pale

blue, 610 Fah., for saws, the teeth of which are set with pliers; greenish blue, 630 Fah., for very soft temper. To obtain the proper temper lay the metal on a lump of iron heated to a sufficiently strong heat in the forge or other fire. The desired temper may be thus secured with the greatest facility and exactitude, as the clean bright metal shows, the degrees of oxidation from the blue upwards most distinctly, which oxidation can be arrested at will. Cleanliness, or rather brightness of surface, is essential.

Tempering Mill Picks and Chisels.-Heat the bill to a blood-red heat, and then hammer it till nearly cold; again heat it to a blood red, and quench as quick as possible in three gallons of water, in which is dissolved 2 oz. of oil of vitriol, 2 oz. of soda, and

oz. of saltpetre; or, 2 oz. of sal ammoniac, 2 oz. spirit of nitre, 1 oz. oil of vitriol. The bill to remain in the liquor until it is cold. 2. 1 oz. white arsenic, 1 oz. spirits of salts, 1 oz. sal ammoniac, dissolved in four gallons of spring water, and kept in a tube or iron phial for use. Heat the tool to a bloodred heat, then quench it in this mixture, draw it gently over the clean fire till the spittle flashes off it, then let it cool. 3. To 3 gallons of water add 3 oz. of spirit of nitre, 3 oz. of spirits of hartshorn, 3 oz. of white vitriol, 3 oz. of sal ammoniac, 3 oz. of alum, 6 oz. of salt, with a double handful of hoof parings; the steel to be heated a dark cherry red. Used to temper chisels for cutting French burr stones.

Tempering Cast Steel.-Dissolve a small quantity of sal ammoniac in water, make the metal red, drop it into the mixture for a second or two, and take it out, leaving enough heat in the metal to draw it back a bit. If left till cold, the steel will be a great deal too hard.

Tempering Springs. Get a piece of spring steel about the size of spring wanted; when forged and filed to tilt, make it warm-red, immerse in spring water (a little cow-dung improves it, mixed well with the water

before using it). Dry the spring, then tie a piece of wire fast to the spring in any form, so as to hold it. Dip in clean tallow or oil, put it on the fire till all the grease is burnt off, and swing round and round as swift as you can till cold. Malleable Iron.-2 oz. fluoric acid, 1 oz. nitric acid, 1 oz. saltpetre, to 10 lbs. of metal. When the metal is melted, add the solution. It can be made in a crucible in a brass furnace. When you have cast off patterns, the castings want keeping at red heat for three or four days in iron boxes in a furnace.

Casehardening Iron.-Procu.e a quantity of old boots, burn these until they become charred, beat off the black and charred portion with a hammer, until sufficient powdered carbon is obtained; then place this powder with the articles to be operated upon into a sheetiron box or a piece of wrought-iron gaspipe sufficiently large, taking care that the articles are well covered and in the centre of the mass; lute the ends or top of the box with clay, and place the whole into a fire made of coke, keeping them there for an hour or more, taking care that the heat shall be equal (between dark red and red); now plunge the contents into water. Should the articles require to be blue, such as the barrels or chambers of pistols, repolish them on an emery wheel, and put them into a sand bath or powdered charcoal, until the blue colour is attained, taking them out immediately this change takes place. The following are mixtures that will do instead of the burnt leather:3 parts of prussiate of potash to 1 sal ammoniac; or 2 parts sal ammoniac, 2 bone-dust, 1 prussiate of potash. Bones, urine, and night-soil, are also used for this purpose. A simple method of casehardening iron is to sprinkle powdered prussiate of potash over it at a red heat and plunge into water; bicromate of potash, with the pith of rams' horns, may be used with good results, instead of the prussiate.

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To Clean Pearls.-Soak them in hot water in which bran has been boiled, with a little salts of tartar and alum,

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This may be improved by rubbing afterwards with fine putty powder and olive oil.

Cleaning Alabaster. Strong soap and water is good for cleaning alabaster; if too much discoloured make a paste with quicklime and water, cover the article well with it, and let it remain all day; wash off with soap and water, rubbing hard the stains. Or supply dilute muriatic acid, having previously washed off dirt and grease.

To Clean Pictures.-Wash with a sponge or a soft leather and water, and dry by rubbing with a silk handkerchief. When the picture is very dirty, take it out of its frame, procure a clean towel, and making it quite wet, lay it on the face of the picture, sprinkling it from time to time with clear soft water; let it remain wet for two or three days; take the cloth off and renew it with a fresh one; after wiping the picture with a clean wet sponge, repeat the process till all the dirt is soaked out; then wash it well with a soft sponge, and let it quite dry: rub it with some clear nut or linseed oil. Spirits of wine and turpentine may be used to dissolve the hard old varnish, but they will attack the paint as well as the varnish if the further action of the spirits is not stopped at the proper time by using water freely.

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Cleaning the Hands.-For cleaning the hands when stained with chemicals:- Put lb. glauber salts, chloride of lime, and 4 oz. of water into a small wide-mouth bottle, and when required for use pour some of the thick sediment into a saucer, and rub it well over the hands with pumice-stone or a

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