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To a diluted colorless solution of chloride of gold, add a few drops of a solution of any salt of tin, or stir the solution of gold with a slip of metallic tin; in either case, the production of a beautiful purple or port wine color will be the immediate result. If the mixture is allowed to settle, it becomes colorless; a purple powder (which is an oxide of gold combined with a little tin) being precipitated. This powder is employed in the painting of china, and is called the purple precipitate of Cassius.
Let fall a drop of a solution of nitrate of silver into a glassful of water, and add to it a grain of common salt. Mutual decomposition of the salts will take place, and chloride of silver (in the form of a white powder) will be precipitated. This precipitate is soluble in ammonia, and blackens on exposure to light.
Add a few drops of a solution of nitrate of copper to a test glass of water; the mixture will be colorless; pour into it a little liquid ammonia. The mixture will then assume a fine deep blue color.
Another. - Ferrocyanide of potassium gives a dense brown precipitate with the salts of copper. This is very delicate.
Put a few leaves of the tea or some of the pickle cut small, into a phial with 2 or 3 drs. of liquid ammonia, diluted with one-half the quantity of water. Shake the phial; when, if the most minute portion of copper be present, the liquid will assume a fine blue color. Or immerse a polished knife-blade; the copper will deposit upon it.
Infusion of galls gives a bluish black, and ferrocyanide of potassium a blue precipitate.
Sulphydrate of ammonia (made by passing a current of sulphuretted hydrogen gas through solution of ammonia until no more is absorbed) gives a flesh-colored precipitate.
Protochloride of tin gives a grayish precipitate. A piece of gold introduced into a solution containing mercury and touched with a piece of iron has the mercury deposited upon it.
Sulphydrate of ammonia gives a black precipitate; chromate of potassa and iodide of potassium, yellow.
Heat in a retort, flask, or test tube, finely powdered chlorate of potassa, mixed with about one-fourth its weight of black oxide of manganese. The gas must be collected by attaching a tube to the flask, the end of which dips under water; a jar full of water being inverted over the end of the delivering tube.
Act on zinc scraps with diluted sulphuric acid; say 1 part of acid to 10 of water. A common bottle with a perforated cork fitted with a glass tube or bit of pipe stem, and another bottle to collect the gas, are all the apparatus required. In collecting the gas, the tube must reach quite to the top of the collecting vessel. Care must he taken that all the air has been driven out of each vessel before a light is applied, or an explosion will ensue.
Heat gently in a flask or retort, nitrate of ammonia (made by adding carbonate of ammonia to nitric acid until no more gas comes off). It should be allowed to stand some time over water before being breathed.
Pour muriatic acid upon fragments of chalk or marble. The gas being heavy may be collected without the use of water, by simply allowing the delivery tube to pass to the bottom of the receiving vessel.
Heat gently a mixture of muriatic acid and black oxide of manganese. It may be collected like carbonic acid. Care must be taken not to inhale it.
To 12 oz. of sulphuric acid, in a glass retort add 2 oz. of sulphur and apply a gentle heat. This is a cheap and easy process.
Pour dilute sulphuric acid on sulphuret of iron. This is made by applying a roll of sulphur to a bar of iron heated white hot, or by heating in a crucible a mixture of 2 parts, by weight, of iron filings and 1 of flowers of sulphur.
Gun-cotton, carefully prepared, is scarcely acted on by the most energetic chemical agents at ordinary temperatures. It may therefore be used as a filter for solutions containing strong acids, alkalies, etc.
Mix with the flour to be tried, a little sulphuric acid; if chalk or whiting be present, an effervescence (arising from the discharge of the carbonic acid of the chalk) will take place; but if the flour be pure, no effervescence is produced.
Pour boiling water on some slices of bread, and then pour into the water some sulphuric acid; if there be any chalk in the bread, an effervescence will ensue as before, but if none be in it, no effervescence will take place.
Soda water is prepared (from powders) precisely in the same manner as ginger beer, except that, instead of the two powders there mentioned, the two following are used: For one glass, 30 grs. of carbonate of soda; for the other, 25 grs. of tartaric (or citric) acid.
Take 2 drs. of fine loaf sugar, 8 grs. of ginger and 26 grs. of carbonate of potassa, all in fine powder; mix them intimately in a Wedgwood's ware mortar. Take also 27 grs. of citric or tartaric acid (the first is the pleasantest, but the last is the cheapest). The acid is to be kept separate from the mixture. The beer is prepared from the powders thus: Take two tumbler-glasses, each half filled with water, stir up the compound powder in one of them, and the acid powder in another, then mix the two liquors; an effervescence takes place, the beer is prepared and may be drunk off.
The effervescence is occasioned by the discharge of the carbonic acid of the carbonate of potass. If the beer is allowed to stand for a few minutes it becomes flat; this is owing to its having lost all its carbonic acid. The cost of these powders is 20 cents a dozen sets.
To ascertain whether or not water he fit for domestic purposes, to a glassful of the water add a few drops of the solution of soap in alcohol. If the water be pure, it will continue limpid; if hard, white flakes will be formed.
Keep it in places where neither light nor heat has access. It is obtained from druggists in rolls; these are put into a phial filled with cold water which has been boiled to expel air from it, and the phial is enclosed in an opaque case.
Plates or vessels of brass or copper are rapidly and firmly coated with tin by boiling them with a solution of stannate of potassa, mixed with trimmings of tin, or by boiling them with tin-filings and caustic, potash or cream of tartar.
The following substances have been used, with more or less success, in preventing and removing the incrustations which are formed by using hard water:--
Powdered charcoal, sal soda, alum, each 1 lb.; sawdust, 8 lbs. Mix. Most of the secret incrustation powders sold are but modifications of this.
By using about 1-60th of potatoes to the weight of water in a boiler, scale will be prevented, but not removed. Their action is mechanical; they coat the calcareous particles in the water, and prevent them from adhering to the metal.
A mixture has been used of 12 parts of chloride of sodium, 2 1/2 parts of caustic soda, 1/8 extract of oak bark, 1/2 of potash, for the boilers of stationary and locomotive engines. The principal agent in this case appears to be the tannin or the extract of oak bark.
Suspended in the boiler and renewed monthly prevent all deposit; even from water containing a large quantity of lime. The action depends principally upon the tannic acid.
Mahogany and oak sawdust has been used to prevent and remove scale; but care must be exercised not to allow it to choke up pipes leading to and from the boiler. Catechu contains tannic acid, and has also been used satisfactorily for boilers. A very small quantity of free tannic acid will attack the iron; therefore, a very limited quantity of these substances should be employed.
This article has also been used with some success in preventing and removing incrustations.
The carbonate of soda has the sanction of Professors Kuhlman and Fresenius, of Germany Grace Calvert, of England, and others. It is satisfactorily employed for the purpose.
The chloride of tin is equal to the muriate of ammonia, and is similar in its action in preventing scale.
Have been employed with some degree of satisfaction. The sulphate, not the carbonate of lime, is the chief agent in forming incrustations. By frequent blowing off, incrustations from carbonate of lime in water will be greatly prevented.
The muriate of ammonia softens old incrustations. Its action is chemical; it decomposes the scale. About 2 oz. placed in a boiler, twice per week, have kept it clean, without attacking the metal.
It is stated that oils and tallow in a boiler prevent incrustations. A mixture, composed of 3 parts of black-lead, and 18 parts of tallow, applied hot, in coating the interior of a boiler, has been found to prevent scale. It should be applied every few weeks.
About 13 lbs. of molasses, fed occasionally into a boiler of 8-horse power, has prevented incrustations for 6 months.
Immerse a small slip of ivory in a weak solution of nitrate of silver, and let it remain till the solution has given it a deep yellow color; then take it out and immerse it in a tumbler of clear water, and expose it in the water to the rays of the sun. In about 3 hours the ivory acquires a black color; but the black surface on being rubbed, soon becomes changed to a brilliant silver.
Add to soluble glass (water-glass) an excess of muriatic acid; put it into a box, the bottom of which is made of parchment-paper, afloat on the surface of water (dialysis); after a few days silica, combined with water, will be found in the box. It may be used for the preservation of building-stone, or to render wood fire and water proof.
Paraffine is the best material for lubricating the stoppers of bottles containing caustic alkali, as it is not acted upon by chemical agents under ordinary circumstances, and lubricates perfectly.
1. Tap the stopper gently, upwards and sideways, with a bit of wood.
2. Fasten the upper part of the stopper in the crack of a door or a drawer, and work the bottle gently from side to side.
3. Fasten a string firmly around the stopper (see KNOTS), attach it to a fixed body, and jerk the bottle suddenly downward.
4. When the stopper adheres on account of the solidification of matters dissolved in the liquid in the bottle, a little of the same liquid poured around the base of the stopper, and allowed to remain awhile will often dissolve the hardened matter, and free the stopper.
5. The most effectual way, but one requiring care, is to heat the neck of the bottle evenly and rapidly over an alcohol or gas-flame. The neck expands sooner than the stopper, and it is very rarely that any difficulty is found in the removal of the latter. If the bottle contain inflammable liquids, it is safer to wrap a cloth dipped in boiling water around the neck, instead of exposing it to the naked flame.
Wash alternately, with a camel's-hair brush dipped in a solution of oxalic acid and cyanide of potassium.
Dissolve 50 grains of disulphide of quinine in 2 fl. oz. of acetic acid, and 2 oz. of proof-spirit warmed to 130° Fahr., in a very wide-mouthed flask or glass beaker; then slowly add 50 drops of a mixture of 40 grs. of iodine in 1 oz. of rectified spirits; agitate the mixture, and then set it carefully aside for 6 hours, in an apartment maintained at a temperature of about 50° Fahr. The utmost care must be taken to avoid any motion of the vessel; indeed, all accidental vibrations should be guarded against by suspending the vessel by a string, or by allowing it to rest on a mass of cotton and wool. If, in 6 hours, the large laminae of the salt have not formed, warm the fluid with a spirit lamp, and when it has become clear, add a few drops of the solution of iodine in spirit. The large laminae form on the top of the fluid, and should be removed carefully by gliding under one of them a circular piece of thin glass. The specimen should be drained by resting the edge of the glass on a piece of bibulous paper, but it must not be touched on account of its extreme fragility; if any small crystals adhere to its surface, they must be washed off by pouring over it a few drops of watery solution of iodine. When dry the specimen should be placed for a few minutes under a bell-glass by the side of a watch-glass, containing a few drops of tincture of iodine; and, lastly, very little fluid Canada balsam should be dropped on it, and a thin glass cover applied without heat. Specimens may thus be obtained of extreme thinness, and 1/2 an inch in diameter, or even larger, possessing scarcely the slightest color, and yet completely polarizing transmitted light.
Excellent buttons) and even handsome cameos, may be made with talc or steatite, provided, after they are made, they be heated for several hours at a nearly white heat. By this strong calcination the steatite gets so hard that it strikes fire with flints, and resists the best tempered file. They may be polished by emery, tripoli, and jeweller's putty; and colored by mineral or organic matters; chloride of gold colors them purple, nitrate of silver, black; exposure to the reducing flame increases very much the brilliancy of the color.
When a solid body becomes liquid, a liquid vapor, or, when a gas or vapor expands, heat is abstracted from neighboring bodies, and the phenomena or sensation of cold is produced.
Evaporation produces cold, as is seen familiarly in the chilliness caused by a draught of air blowing on the moist skin. Water may be cooled to 30°, in warm climates, by keeping it in jars of porous earthenware; a flower-pot, moistened and kept in a draught of air, will keep butter, placed beneath it, hard in warm weather. In India water is exposed at night in shallow pans, placed on straw in trenches, and freezes even when the thermometer does not fall below 40°. Water may be frozen by its own evaporation under the receiver of an air-pump over sulphuric acid; the process is a delicate one, and not adapted for use on the large scale.
Twining's ice-machine freezes water by the evaporation of ether, aided by the vacuum produced by a pump worked by a steam-engine. The same ether may be used over again indefinitely. The apparatus works well, but, in case of a leak, the ether vapor, mixed with air, would explode; there is always danger of fire.
Freezes by the evaporation of liquid ammonia, the ammoniacal gas produced being absorbed by water which will take up over 500 times its bulk of the ammonia, which it gives out again on heating. As liquid ammonia boils at 42° below zero, an intense cold is produced. This apparatus is efficient, but as the internal pressure rises sometimes to over 100 lbs. to the inch, it is not quite safe, although no accidents have yet been reported.
Air, when compressed, gives out heat which is reabsorbed when it is allowed to expand. By forcing the air into a strong receiver and carrying off the heat developed by a stream of water, it may, on expanding, re-absorb enough to reduce the temperature below 32°. It is thus used in the paraffine works in England, and would be an excellent method of at once ventilating and cooling large buildings.
Depend upon the conversion of solid bodies into liquids. There are two classes, those used without ice and those in which it is employed. Where extreme cold is required, the body to be frozen should be first cooled as much as possible by one portion of the mixture, and then by a succeeding one.
Without Ice. - Four oz. each of nitre and sal ammoniac in 8 of water will reduce the temperature from 50° to 10°.
Equal parts of nitrate of ammonia and water, from 50° to 4°. The salt may be recovered by evaporation and used over again.
Equal parts of water, crystallized nitrate of ammonia, carbonate of soda, crystallized and in powder, from 50° to 7°.
Five parts of commercial muriatic acid and 8 of Glauber's salt in powder, from 50° to 0°.
With Ice. - Snow is always preferable. Ice is best powdered by shaving with a plane like a carpenter's, or it may be put into a canvas bag and beaten fine with a wooden mallet.
Equal parts of snow and common salt will produce a temperature of --4°, which may be maintained for hours. This is the best mixture for ordinary use.
Three parts of crystallized chloride of calcium and 2 of snow will produce a cold sufficient to freeze mercury, and to reduce a spirit thermometer from 32° to--50°. The chloridemay be recovered by evaporation. There are many other freezing mixtures given in the books, but none are so cheap and efficient as the above.
Antiseptics are bodies which prevent or retard decay; disinfectants those which are supposed similarly to retard or prevent the spread of disease whether epidemic or contagious. The latter term, however, is popularly applied to deodorizers or bodies which remove the offensive swell accompanying decaying organic matter.
Salt, spices and sugar are too well known to require comment. Professor Morgan's method of salting meat is to inject the brine into the aorta, or main artery; this process is highly recommended on the score of simplicity and economy. Alcohol and glycerine are used as preservative solutions. The latter does not shrink or alter the color of animal or vegetable substances preserved in it.
1. (For ordinary use in preserving specimens.) Alum, 1 oz.; bay salt, 2 oz.; corrosive sublimate, 1 gr.; water, 1 pt. In very tender tissues, or where there is a tendency to mouldiness, use 2 grs. of corrosive sublimate.
2. (For objects containing carbonate of lime.) Bay salt, 1/4 lb.; corrosive sublimate, 1 gr.; water, 1 pt.
3. (For old preparations.) Bay salt, 1/4 lb.; arsenious acid (white arsenic), 10 grs.; water, 1 pt. Dissolve by the aid of heat. When there is a tendency to softening, add 1 gr. of corrosive sublimate.
Nitre, 1 part; alum, 2 parts; chloride of lime, 4 parts; water, 16 or 20 parts.; to be diluted as may be necessary. For pathological specimens.
Alum, 2 1/2 oz.; nitre, 1 qt.; water, l qt.
Is made by adding scrap zinc to muriatic acid so long as any gas (hydrogen) is evolved. If it be required neutral, add carbonate of soda until a slight precipitate is seen. It is largely used in the preservation of timber, and in embalming, being in the latter case injected into the aorta.
Is a strong solution of corrosive sublimate in water; used for the same purposes as Burnett's, but now generally superseded by the latter.
Is used to preserve wood; it is boiled and applied as a paint, or forged into the pores of the wood under pressure.
The only true method to prevent the spread of contagious or epidemic diseases is thorough cleanliness. Abundance of air to dilate the poison, and the removal of organic liberal use of water or soap and water, are effectual. Lime acts by destroying organic matter and absorbing certain offensive gases. Hence the use of whitewashing. Sulphurous acid checks organic change or fermentation. A high temperature, say 240° Fahr., is useful in disinfecting clothes, letters, etc. Condy's Solution acts by destroying organic matter; solutions of chloride of zinc, corrosive sublimate, persulphate or perchloride of iron act by coagulating certain organic matters and preventing further decay; they also absorb sulphuretted hydrogen. Chloride of lime (bleaching salt), chlorine, nitrate of lead, and copperas are merely deodorizers. Pastils (see PERFUMERY), burned sugar vinegar, and burning tar, merely disguise offensive odors.
A saturated solution of permanganate of potassa is one of the most efficient and elegant of all disinfectants. A teaspoonful in a soup-plate of water, exposed in a room, quickly removes any offensive smell; when the pink color disappears more must be added. It has been used to remove the smell of bilge-water and guano from ships. It speedily cleanses foul water and makes it drinkable. A teaspoonful to a hogshead is generally enough, but more may be added, until the water retains a slight pinkish tint. This will disappear, by putting a stick into the water for a few minutes.
Litharge, 13 1/2 oz.; nitric acid, s. g. 1.38, 12 oz., previously diluted with water, 6 pts. It contains nitrate of lead, and is merely a deodorizer.
Free chlorine is seldom used, on acount of its offensive and suffocating qualities.
Chloride of lime contains hypochlorite of lime and chloride of calcium and lime. It is made into a paste with water; acids cause it to evolve chlorine.
Eau de Javelle is made by adding to chloride of lime 1 part, water 16 parts and agitate at intervals for an hour, then dissolve 2 oz. carbonate of potassa in 1/4 pint water. Mix the solutions, and when the mixture has settled pour off the clear part. Or, by passing a stream of chlorine through a solution of carbonate of potassa to saturation. It contains hypochlorite of potassa and chloride of potassium.
Pass chlorine through a solution of carbonate of soda (1 lb. in water 1 qt.) to saturation; or, to a mixture of chloride of lime 1/2 lb., and water 3 pints, add 7 oz. crystallized carbonate of soda, in 1 pt. of water. Proceed in all respects as for Eau de Javelle. These solutions will remove fruit-stains from linen.
Perchloride of Iron is made by dissolving iron in muriatic acid, and while boiling add nitric acid as long as red fumes are evolved. It is a powerful styptic.
Monsel's Solution, subsulphate of iron, is made by dissolving copperas 12 oz. (troy), in water 12 oz., adding sulphuric acid 510 grs., and then while boiling adding nitric acid as long as red fumes come off. It is much used as a styptic and astringent, and is a cheap and powerful deodorizer. Copperas mixed with 1/2 its weight of lime is a cheap and popular agent in deodorizing sinks.
Or coal-tar creosote, coagulates organic matter; is a powerful antiseptic and deodorizer. It is used mixed with lime. Ridgewood's disinfecting powder contains 5 to 8 per cent. each of lime and of carbolic acid, and 70 to 80 per cent. of fuller's earth.
Is a useful deodorizer and purifier; it acts by its attraction for organic matter and gases. By condensing the latter as well as the oxygen of the air in its pores it causes rapid combination. Small animals buried in charcoal are rapidly converted into skeletons, while no offensive smell is noticed even in warm weather. Water is best kept in charred casks; foul water is purified by filtration through charcoal. Meat lightly tainted is restored by wrapping in powdered charcoal; animal charcoal is the best. Lampblack is nearly worthless for these purposes. Animal charcoal is an antidote to all animal and vegetable poisons; it rapidly removes organic coloring matters and also vegetable bitters from solution. Picric acid is not thus removed, and may in this way be detected when used instead of hops in brewing.
To prevent the effects of noxious vapors from wells, cellars, fermenting liquors, etc., procure a free circulation of air, either by ventilators, or opening the doors or windows where it is confined, or by keeping fires in the infected place; or throwing in lime, recently burnt or powdered.
Old wells, vaults, and sewers, which have been long shut up from the air, are generally occupied by vapors which soon prove fatal to persons breathing them. The property which these vapors have of extinguishing flame, affords the means of detecting their presence and thereby avoiding the danger of an incautious exposure to them. When such places, therefore, are opened to be cleaned out or repaired, a lighted candle should be let down slowly by means of a cord, before any person is suffered to descend; and if it burns freely until it gets to the surface of the water, or other matter covering the bottom, the workmen may then venture down with safety. But, if, without any accident, the candle is extinguished, and continues to be so on repeated trials, then the air of the place is highly noxious.
Is made by immersing unsized paper for a few seconds into a mixture (cold) of 2 parts, by measure, of commercial sulphuric acid, and 1 part of water; then washing in water, and afterwards in dilute solution of ammonia. It is water-proof, about 6 times as strong as paper, and may be used in all cases as a substitute for parchment, which it resembles. The same effect is procured by soaking paper in a solution of neutral chloride of zinc, s. g. 2100. It is then treated as before. This paper is used in Mr. Graham's process for dialysis.
Reduce to a powder, and dissolve quickly in a glazed earthen vessel, containing cold water, some gum tragacanth, having been well worked with a wooden spatula, to free it from lumps. There must be a sufficient quantity of water, to give to this diluted gum the consistence of a jelly. Paper, and some sorts of stuffs, upon which, if this composition be smoothly applied, with a pencil or a brush, and dried before a gentle fire, will receive either water or oil colors; in using water colors, they must be mixed with a solution of the above gum. This cloth or paper, so prepared, will take any color except ink. When it is intended to retouch any particular part of the drawing, it should be washed with a sponge, or clean linen, or a pencil (containing some of the above-mentioned liquid); if the part is only small, it will then rise quickly, and appear as if repainted.
A sheet of thin iron-plate was placed over the marks made, and supported by an iron stand, at a distance of about 1 1/2 inches from the surface of the ground; a quantity of lighted charcoal was then placed on the iron plate, which soon became red hot, and of course heated the spot over which it was placed. When the latter was raised to 100° Centigrade (212° Fahr.) the fire, together with the plate, was removed, and a quantity of finely divided stearic acid was strewed over the impression by means of a sieve. The powder used was that of a common stearine candle, dissolved by heat in alcohol, and then thrown into a large quantity of cold water, when the stearine falls to the bottom in the form of a fine precipitate. This powder is so light and impalpable, that it is said it might be sifted over an impression in the dust of a common road, without, in the slightest degree, interfering with the faintest mark. The instant it touched the heated surface of the ground in question it melted, and, as it were, sealed the whole of the loose atoms into one compact mass. When a sufficient quantity of the stearine had been applied the place was left until it had become completely cold; the surrounding earth was then dug out carefully at some little distance from the edges of the impression, and the portion containing this latter was lifted up in one entire block and laid on a cloth several times doubled, the edges of which were raised up so as to form a kind of border, or rather framing, into which, and against the sides of the sandy earth containing the impression, plaster of Paris was poured, and when the latter was set, the whole could be handled without danger, and was firm enough to bear packing and carriage to any distance. It is evident, therefore, that if necessary it might also be used as a mould, from which casts in plaster could be obtained. The value of such a process, as an aid in criminal cases, is too self-evident to require demonstration; the production of the tell-tale impressions in a court of justice, where every mark can be conveniently exhibited and compared with the object by which it was produced, may be equally useful in the proof of guilt and of innocence, and it would be strange, indeed, if a use for such a process be not discovered in matters of scientific or practical interest.
The following simple process will make lead pencil writing or drawing as indelible as if done with ink. Lay the writing in a shallow dish, and pour skimmed milk upon it. Any spots not wet at first may have the milk placed upon them lightly with a feather. When the paper is all wet over with the milk take it up and let the milk drain off, and whip off with the feather the drops which collect on the lower edge. Dry it carefully, and it will he found to be perfectly indelible. It cannot be removed even with India-rubber. It is an old recipe and a good one.
Whether the paper be plain, written, printed on, or even marbled, stained, or painted for hangings, dip it in a strong solution of alum-water and then thoroughly dry it. In this state it will be fireproof. This will be readily known by holding a slip thus prepared over a candle. Some paper requires to imbibe more of the solution than by a single immersion, in which case the dipping and drying must be repeated until it becomes fully saturated. Neither the color nor quality of the paper will be in the least affected by this process, but, on the contrary, will be improved.
Glass made by heating sand with twice its weight of soda-ash or pearlash is soluble in boiling water, when finely powdered. Applied with a brush, it renders woodwork fireproof, and when once dry is not affected by cold water.
Take of a solution of tungstate of soda, of a specific gravity 1.14, 100 parts; phosphate of soda, 3 parts. The articles are dipped in the solution, and allowed to dry before ironing. This solution keeps well, and is used in the Royal laundry.
Three persons out of 4 would rush right up to the burning individual, and begin to paw with their hands without any definite aim. It is useless to tell the victim to do this or that, or call for water. In fact, it is generally best to say not a word, but seize a blanket from a bed, or a cloak, or any woollen fabric -- if none is at hand, take any woollen material -- hold the corners as far apart as you can, stretch them out higher than your head, and, running boldly to the person, make a motion of clasping in the arms, most about the shoulders. This instantly smothers the fire and saves the face. The next instant throw the unfortunate person on the floor. This is an additional safety to the face and breath, and any remnant of flame can be put out more leisurely. The next instant, immerse the burnt part in cold water and all pain will cease with the rapidity of lightning. Next, get some common flour, remove from the water, and cover the burnt parts with an inch thickness of flour, if possible; put the patient to bed, and do all that is possible to soothe until the physician arrives. Let the flour remain until it falls off itself, when a beautiful new skin will be found. Unless the burns are deep, no other application is needed. The dry flour for burns is the most admirable remedy ever proposed, and the information ought to be imparted to all. The principle of its action is that, like the water, it causes instant and perfect relief from pain, by totally excluding the air from the injured parts. Spanish whiting and cold water, of a mushy consistency, are preferred by some. Dredge on the flour until no more will stick, and cover with cotton batting.
Wash in hot dilute soda lye; then immerse in dilute muriatic acid, 1 part to 10 of water, until all gritty particles are removed, and no more gas arises; then immerse in a second bath of dilute muriatic acid, containing 3 per cent. of hyposulphite of soda, for 48 hours.
Wet the linen where spotted in Labarraque's Solution (solution of chlorinated soda), or solution of chloride of lime (bleaching salt), or chlorine water; it will immediately disappear. Wash out at once with warm water. This is a better plan than that given in p. 314. Fruit and wine stains of all kinds may be removed in the same manner.
A tablespoonful of pulverized alum sprinkled into a hogshead of water (the water stirred at the same time) will, after a few hours, by precipitating to the bottom the impure particles, so purify it that it will be found to possess nearly all the freshness and clearness of the finest springwater. A pailful, containing 4 gallons, may be purified by a single teaspoonful of the alum.
Another. - to a hogshead of water a tablespoonful of a saturated solution of permanganate of potassa; this effectually destroys all organic matter. If the water retain a pink hue, put a stick or chip in it when the color will shortly disappear.
Saturate the wood in a weak solution of copperas, for joists, beams, rafters, and floorings; or soak the wood in lime-water, suffering it to dry, and then apply water in which there is a weak solution of vitriolic acid; or wash it with a strong solution of potash, then with pyroligneous acid in which the oxide of lead or iron has been dissolved, and finally, with alum-water.
A current of air under a floor will always prevent the dry-rot, and stop it when it has commenced.
In boarding kitchens and other rooms on the basement story, the planks should be steeped in a strong solution of vitriol or alum, and when they are dried, the side next to the earth should receive a coat of tar or common paint.
The following have been employed. They are forged into the pores of the wood by putting it into a close vessel, exhausting the air, and then allowing the liquid to flow in. In some cases the timber is merely immersed; in others the liquid flows in under heavy pressure. In Boucherie's method the green tree is felled, the branches trimmed off, and a bag containing sulphate of copper or other antiseptic agent attached to the butt. The sap is gradually expelled by displacement, and flows from the free end of the log, the antiseptic solution taking its place.
These solutions probably act by coagulating the albuminous matters of the wood, and thus preventing the beginning of decay or dry-rot. They also prevent the attacks of insects. Corrosive sublimate (Kyan), chloride of zinc (Burnett), sulphate of copper (Boucherie), chloride of calcium followed by sulphate of iron (Payne), crude pyroligneous acid, saturated with iron scraps (Bethell), coal tar.
Well-seasoned timber may be preserved by charring the surface. The process adopted in the French dockyards is to use a jet of mixed goal-gas and air; the two being conveyed by India-rubber tubes, which unite at the jet. The air is forged in by a bellows worked by the foot of the operator. A slight previous coating of tar is useful by filling up cracks, and causing a uniformity of action of the flame.
The face of the planks should be cut in the direction from east to west as the tree stood. The strongest side of a piece of timber is that which, in its natural position, faced the north.
Mix together fuller's earth and soap lees, and rub it into the boards. Let it dry and then scour it off with some strong soft soap and sand, or use lees to scour it with. It should be put on hot, which may easily be done by heating the lees.
Logs and planks split at the ends because the exposed surface dries faster than the inside. Saturate muriatic acid with lime and apply like white-wash to the ends. The chloride of calcium formed attracts moisture from the air, and prevents the splitting.
The Cosmos reports from the other journals a simple mode, said to have been adopted from immemorial times in the ship-yards of Venice, for ascertaining the fitness of timber for their constructions. "A person applies his ear to the middle of one of the ends of the timber, while another strikes upon the opposite end. If the wood is sound and of good quality, the blow is very distinctly heard, however long the beam may be. If the wood were disaggregated by decay or otherwise, the sound would be for the most part destroyed.
Polished iron-work may be preserved from rust by a mixture not very expensive, consisting of copal varnish intimately mixed with as much olive-oil as will give it a degree of greasiness, adding thereto nearly as much spirit of turpentine as of varnish; or varnish with wax dissolved in benzine. The cast-iron work is best preserved by rubbing it with black-lead.
But where rust has begun to make its appearance on grates or fire-irons, apply a mixture of tripoli, with half its quantity of sulphur, intimately mingled on a marble slab and laid on with a piece of soft leather; or emery and oil may be applied with excellent effect; not laid on in the usual slovenly way, but with a spongy piece of the fig-tree fully saturated with the mixture. This will not only clean, but polish, and render the use of whiting unnecessary.
Brass ornaments, when not gilt or lackered, may be cleaned in the same way, and a fine color may be given to them by two simple processes. The first is to beat sal ammoniac into a fine powder, then to moisten it with soft water, rubbing it on the ornaments, which must be heated over charcoal and rubbed dry with bran and whiting. The second is to wash the brass work with roche alum boiled in strong lye, in the proportion of an ounce to a pint. When dry it must be rubbed with fine tripoli. Either of these processes will give to brass the brilliancy of gold.
A very easy and elegant way of taking the impressions of medals and coins, not generally known, is thus described by Dr. Shaw: Melt a little isinglass glue with brandy, and pour it thinly over the metal so as to cover its whole surface; let it remain on for a day or two, till it is thoroughly dried and hardened, and then taking it off it will be fine, clear, and as hard as a piece of Muscovy glass, and will have a very elegant impression of the coin. It will also resist the effects of damp air, which occasions all other kinds of glue to soften and bend if not prepared in this way.
A substitute for metal in the manufacture of gasburners, journal bearings, taps, etc., is made of finelypowdered soapstone, pressed into moulds and annealed.
Soapstone powder, in the form of dust, is proposed as a lubricant for the axles of machines. For this purpose it is prepared as follows: It is first reduced to the condition of very fine powder; then it is washed to remove all gritty particles; then it is steeped for a short period in dilute muriatic acid (about 1 qt. of acid to 20 of water), in which it is stirred until all particles of iron which it contains are dissolved. The powder is then washed in pure water again, to remove all traces of acid; then it is dried, and is the purified steatite powder used for lubrication. It is not used alone, but is mixed with oils and fats, in the proportion of about 35 per cent. of the powder, added to paraffine, rape, or other oil. This steatite powder, mixed with any of the soapy compounds, which are also now used, in many cases, for lubrication also answers a good purpose. It is chiefly intended for heavy machinery, such as the journuls of waterwheels, railway and other carriages.
Make sand or gravel into a paste with fluid silicate of soda (water-glass), mould it to the desired shape, and dip into a solution of chloride of calcium. This solution is made by neutralizing muriatic acid with lime, chalk, limestone, or marble. The mass becomes solid in a few minutes, and is exceedingly strong and durable.
A ready way of imitating ground glass is to dissolve Epsom salts in beer, and apply with a brush. As it dries it crystallizes.
Wet an ordinary drill with petroleum or benzine; turpentine will answer, but not so well; it will then bore common glass nearly as rapidly as steel. If it is intended to bore through, the glass should be first countersunk on each side with a drill dressed off so as to form a very flat threesided pyramid. Flint and plate-glass are very difficult to bore.
The electro-magnetic coil has, in a great measure, superseded the electric machine; the latter, however, will never cease to be an object of interest, and, it is probable, will always be preferred for some purposes. The expense and difficulty of managing large plates and cylinders of glass have hitherto been obstacles to the use of large electric machines. These obstacles appear now removed--glass being rendered unnecessary by the discovery of a far more convenient and effective material. M. Edmond Bequerel exhibited to the Academy of Sciences on a recent occasion an electric machine, the plate of which was made of indurated red sulphur, the invention of a civil engineer. It was 80 centimetres in diameter, and afforded a spark 14 centimetres in length. No amalgamated cushions were required with it, the skin of a cat being quite sufficient to produce every desired effect. Sulphur undergoes extraordinary changes by successive fusions, becoming extremely hard and tenacious. After the third fusion it no longer acts on metals, or possesses its characteristic odor. The plate used by M. Bequerel was formed by fusing the sulphur 3 times in a cast-iron vessel, at a temperature between 250° and 300° Cent., and allowing it, after each fusion, to cool thoroughly.
After the 1st and 2nd fusions it was crushed to a coarse powder, and, after the 3rd, it was poured into a plaster-mould. Plates, 4 metres in diameter, may easily be made in this way; they cost extremely little, and, besides being more efficient, are far less hygrometric than glass.
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