covered either with powdered charcoal and water, or fine brick-dust and water; after the work has been made as smooth as possible with this, it is followed by another buff, or bob, on which washed chalk, or dry whiting, is rubbed; the comb, or other article to be polished, is moistened slightly with vinegar, and the buff and whiting will produce a fine gloss, which may be completed by rubbing it with the palm of the hand, and a small portion of dry whiting, or rotten-stone.

ORGANIC AND INORGANIC KINGDOMS. THE beautiful world in which we are placed, is everywhere full of objects presenting innumerable varieties of form and structure, of action and position; some of them being inanimate or inorganic, and others possessing organization or vitality. The organic kingdom of nature, in like manner, is separated into two grand divisions, the animal and vegetable. The differences between organic and inorganic bodies are numerous and manifest. All the parts of an inorganic body enjoy an independent existence; if a crystal be broken from this mass, the specimen does not lose any of its properties, it is still a mass of crystals as before; but if a branch be removed from a tree, or a limb from an animal, both are rendered imperfect, and the parts removed suffer decomposition-the branch withers, and the animal matter undergoes putrefaction. But if crystals, which may be considered the most perfect models of inorganic substances, be formed, they will continue the same, unless acted upon by some external force of a chemical or mechanical nature. Within, every particle is at rest, nor do they possess the power to alter, increase or diminish: they can augment by external additions only, and decrease but by the removal of portions of their mass. organic bodies have characters of a totally different nature; they possess definite forms and structures, which are capable of resisting for a time the ordinary laws by which the changes of inorganic matter are regulated, while internally they are in constant mutation. From the first moment of the existence of the plant or animal to the period of its dissolution there is no repose; youth follows infancymaturity precedes age; it is thus with the moss and the oak-the monad and the elephant-life and death are common to them all. Animals and vegetables also require a supply of food and air, and a suitable temperature, for the continuance of their existence; and they are nourished by particles prepared in appropriate organs, and conveyed by suitable vessels. From the very first germ of an animal or a vegetable, there is a vital principle in action, by which are developed in succession the ordained phenomena of its existence. By this

But

power the germ is able to attract towards it particles of inanimate matter, and bestow on them an arrangement widely different from that which the laws of chemistry or mechanics could produce. The same power not only attracts these particles, and preserves them in their new situations, but is continually engaged in removing those which might by their presence prevent or derange its operations; and on the other hand, so soon as the vital principle deserts the body which it has animated, the latter immediately becomes subject to the agencies which act on inorganic matter: "in obedience to the power of gravitation the bough hangs down, and the slender stem bends towards the earth-the

animal falls to the ground-the pressure of the upper parts flattens those on which they rest-the skin becomes distended, and the graceful outlines of life are changed for the oblateness of death,"— the laws of chemistry then begin to operate-putrefaction takes place--and, finally, dust returns to dust, and the spirit of man to Him who gave it.

MISCELLANIES.

Serpents. In the savannahs of Izacubo, in Guiana, I saw the most wonderful, the most terrible spectacle that can be seen; and although it be not uncommon to the inhabitants, no traveller has ever mentioned it. We were ten men on horseback, two of whom took the lead, in order to sound the passages, whilst I preferred to skirt the great forests. One of the blacks who formed the vanguard, returned full gallop, and called to me, "Here, sir, come and see serpents in a pile." He pointed out to me something elevated in the middle of the savannah or swamp, which appeared like a bundle of arms. One of my company then said, "This is certainly one of the assemblages of serpents, which heap themselves on each other after a violent tempest: I have heard of these, but have never seen any let us proceed cautiously, and not go too near." When we were within twenty paces of it, the terror of our horses prevented our nearer approach, to which, however, none of us were inclined.

On a sudden, the pyramid mass became agitated ! Horrible hissings issued from it, thousands of serpents rolled spirally on each other, shot forth out of the circle their hideous heads, presenting their envenomed darts and fiery eyes to us. I own I was one of the first to draw back; but when I saw this formidable phalanx remained at its post, and appeared to be more disposed to defend itself than to attack us, I rode round it, in order to view its order of battle, which faced the enemy on every side. I then sought what could be the design of this numerous assemblage; and I concluded that this species of serpents dreaded some colossal enemy, which might be the great serpent, or the cayman, and that they reunite themselves, after having seen this enemy, in order to attack or resist him in a mass.-Humboldt.

Crystallized Tin.-M. Baget, a Frenchman, claims the honor of the discovery of this process. It may be done as follows:-After cleansing away every extraneous matter, as dirt or grease, with warm soapy water, rince the tin in clean water; then, after drying it, give it a heat to the temperature of bare sufferance to the hand, and expose it to the vapour of any acid that acts upon tin, or the acid itself may be poured on, or laid on with a brush, the granular crystallization varying according to the strength of the wash, and the heat of your plates. Hence, it must be perceived, whatever quantity is required for any particular job of work should be made all at one time; no two makings coming away alike, but depending entirely upon accident.

Wash 1. Take one part by measure of sulphuric acid, and dilute it with five times as much water. 2. Take of nitric acid and water, equal quantities, and keep the two mixtures separate.

Then, take of the first ten parts, and one part of the second; mix, and apply the same with a pencil or sponge to the surface of the heated tin, repeating the same several times, until the material

1

acted upon loses its heat, or you may be satisfied with the appearance of your work. A transparent varnish is now to be laid on, much whereof will be absorbed, and will of course be affected by any coloring matters you may mix with it; these, however, should not be opaque colors; and a good polish being given to the work, produces that enviably brilliant covering we find so much in use for covering iron story posts, &c.

Temporary Nautical Pump.-Captain Leslie, in a voyage from North America to Stockholm, adopted an excellent mode of emptying water from a ship's hold, when the crew were insufficient to perform that duty. About ten or twelve feet above the pump, he rigged out a spar, one end of which projected overboard, while the other was fastened as a lever to the machinery of the pump. To the end which projected overboard, was suspended a water butt, half full, but corked down; so that when the coming wave raised the butt-end, the other end depressed the piston of the pump; but at the retiring of the wave, the thing was reversed, for, by the weight of the butt, the piston came up again, and with it the water. Thus, without the aid of the crew, the ship's hold was cleared of the water in a few hours.

Turkish Glue, or Armenian Cement.—The jewellers of Turkey, who are mostly Armenians, we are informed by that most respectable and intelligent traveller, Mr. Eton, formerly a consul in that country, and author of the celebrated "Survey of the Turkish Empire," have a singular method of ornamenting watch-cases, &c., with diamonds and other precious stones, by simply glueing or cementing them on. The stone is set in silver or gold, and the lower part of the metal made flat, or to correspond with the part to which it is be fixed; it is then warmed gently, and has the glue applied; which is so very strong, that the parts thus cemented never separate; this glue, which will strongly unite bits of glass, and even polished steel, and may of course be applied to a vast variety of useful purposes, is thus made :-Dissolve five or six bits of gum mastic, each the size of a large pea, in as much spirits of wine as will suffice to render it liquid, and, in another vessel, dissolve as much isinglass (previously a little softened in water, though none of the water must be used,) in French brandy or good rum, as will make a two-ounce phial of very strong glue; adding two small bits of gum albanum or ammoniacum, which must be rubbed or ground till they are dissolved. Then mix the whole with a sufficient heat. Keep the glue in a phial closely stopped, and when it is to be used set the phial in boiling water. Mr. Eton observes, that some persons have sold a composition under the name of Armenian cement in England; but this composition is badly made; it is much too thin, and the quantity of mastic is much too small. Good cement made in the manner described is as thick as strong carpenter's glue.

are stated to be of the following nature:-If the weather promise to be fine, the solid matter of the composition will settle at the bottom of the glass, while the liquid will remain transparent; but previous to a change for rain the compound will gradually rise, the fluid continue pellucid, and small stars will be observed moving or floating about within the vessel. Twenty-four hours before a storm, or very high wind, the substance will be partly on the surface of the liquid, apparently in the form of a leaf: the fluid in such case will be very thick, and in a state resembling fermentation. During the winter, small stars being in motion, the composition is remarkably white, and somewhat higher than usual, particularly when white frosts or snows prevail. On the contrary, in the summer, it the weather be hot and serene, the substance subsides closely to the bottom of the glass tube.

Lastly, it may be ascertained from what quarter of the compass the wind blows, by observing that the solid particles adhere more closely to the bottom on the side opposite to that where the tempest arises.

Sugar from Starch, Wood, &c.-The chemical constituents of these different substances differ but little. The abstraction of a small portion of the carbon and hydrogen from starch converts it into sugar. By digesting potatoes with diluted oil o. vitriol for a day or two, at a temperature of 212° Fahr., afterwards removing the acid by chalk, and concentrating the strained liquor by evaporation, crystals of sugar will be obtained. Saussure produced 110 parts of sugar from 100 parts of starch. from which he concluded that sugar was a peculiar M. Braconnot compound of water and starch.

treated elm dust with oil of vitriol in the same manner as the starch, neutralizing the acid with chalk, and obtained a liquor which became gummy on evaporation. By triturating linen rags in a glass mortar with sulphuric acid, a similar gum is produced. If the gummy matter is boiled with diluted oil of vitriol, a crystallizable sugar is obtained.

The Light of the Sun and Moon.-The direct light of the sun has been estimated to that of 5,563 wax candles, of moderate size, placed at a distance of one foot. The light of the moon is about equal to that of one wax candle at the distance of twelve feet.

QUERIES.

THE art of lighting houses, streets, and manufactories, with carburetted hydrogen, or coal gas, is one of those modern discoveries on which the admirers of science, and the inhabitants of this country in particular, have greater reason to congratulate them. selves than any other invention or discovery of the present age.

This art is so wonderful and important, it speaks so forcibly by the effects it has already produced, that it cannot fail to increase the wealth of the nation by adding to the number of internal resources, as long as coal continues to be dug in this island from the bowels of the earth.

For if we estimate the catalogue of human wants which a civilized state of society has introduced, the production and supply of artificial light, holds, next to food, clothing, and fuel, the most important place. We might indeed exist without it, but how large a portion of our lives would in that case be condemned to a state little superior in efficacy to that of the animals around us. The flame of a single candle animates a family, every one follows his occupation, and no dread is felt of the darkness of night.

The progress of the gas manufacture has been within these few years uncommonly rapid. The number of gas-lights already in use in the metropolis alone, amounts to upwards of 200,000. The total lengths of mains in the streets through which the gas is conveyed from the gas-light manufacto[SECOND EDITION.]

ries into the houses more than 400 miles. And it may be truly said, that there is scarcely a large town throughout the three kingdoms which has not its own, and in some towns, more than one establishment for the manufacture of this valuable product.

The flame produced from coal, wood, turf, oil, wax, tallow, or other bodies, which are composed of carbon, hydrogen, and oxygen, proceeds from the production of carburetted hydrogen gas, evolved from the combustible body when it has arrived at a certain degree of heat, which varies with the material operated upon.

In the common mode of burning coal in a fireplace, or stove, nearly the whole of this inflammable gaseous matter is lost. We often see a flame suddenly burst from the densest smoke, and as suddenly disappear; and if a light be applied to the little jets that issue from the bituminous part of the coal, they will catch fire and burn with a bright flame; so also if a candle be blown out, and while yet fuming held to another candle still alight, the flame will start across from one to the other, being caught by the gas arising from the fuming candle. The fact is, that the greater part of the carburetted hydrogen gas, capable of affording light and heat, continually escapes up the chimney, during the decomposition of the coal, whilst only a small part is Occasionally ignited, and exhibits the phenomena of the flame.

If coal, instead of being burnt in the way now stated, is submitted at a temperature of ignition in close vessels, all its immediate constituent parts may be collected. The bituminous part is melted out in the form of coal tar, there is disengaged at the same time a large quantity of aqueous fluid, contaminated with a portion of oil, and various ammoniacal salts. A large quantity of carburetted hydrogen, carbonic oxide, carbonic acid, and sulphuretted hydrogen, also make their appearance, and the fixed base of the coal alone remains behind in the distillatory apparatus, in the form of a carbonaceous substance, called coke. The products which the coal furnishes may be separately collected in different vessels. The carburetted hydrogen, or coal gas, when freed from the foreign gases, may be propelled in streams out of small apertures, which when lighted may serve as a flame of a candle, and then form what we call a gas light.

In order to apply this mode of procuring light on a large scale, as now practised with unparallelled success in this country, the coal is put into vessels, called retorts, and which are furnished with pipes connected with reservoirs to receive the distillatory products. The retorts are fixed into a furnace, and heated to redness. The heat developes from the coal the gaseous and liquid products, the latter are deposited in receivers, and the former are conducted through water in which quick lime is diffused; by which the carburetted hydrogen gas is purified. The sulphuretted hydrogen and carbonic acid which were mixed with it, become absorbed by the quicklime, and the pure carburetted hydrogen is stored up in a vessel called the gas-holder, and is then ready for use.

From the reservoir in which the gas has been collected proceed pipes, which branch out into smaller ramifications until they terminate at the place where the lights are wanted, and the extremities of the branch pipes are furnished with stop-cocks to regulate the flow of the gas into the burners or lamps.

The Engraving exhibits an apparatus for the preparation of gas from coal. In this case only one retort is used; but in the larger apparatus, used for public accommodation, several retorts are heated by one fire, and of course save a considerable expense of fuel. These retorts are all made of cast iron, and are generally of an elliptical shape.

The coals are introduced into the cast iron retort or cylinder B, which is placed on its side in the furnace A. The retort is then closed by an air-tight metallic plate, which is fastened to it by bolts and nut-screws. The lower part of the retort is preserved from the action of the fire by a larger half cylinder of cast iron, inclosed in brick-work, placed at some distance below it; by which means the heat is more equally distributed to the pit-coal. As the heat applied to the retorts should be of a regular and uniform temperature, that circumstance requires very attentive observation and care: for if it be not sufficiently strong, all the volatile substances will not be disengaged, and should it on the contrary be too intense, the retorts may be injured, as well as the illuminating quality of the gas be so materially diminished as to render it of less value to the consumer. The degree of heat usually employed is that of a cherry redness; and when the coal has remained in the retorts a sufficient length of time for all its gaseous matter to be expelled, the covers being removed from their mouths, the residue, consisting of the coke, is raked out and falls into a receptacle below them, in order to become cold. At large

establishments, whenever the coke has been taken out of them, the retorts are not suffered to lose their heat, but are immediately replenished with fresh coal to renew the operation, and this practice is continued till the retorts are either damaged by wear, or some other circumstance may require their removal. The proportion of coal required to heat the retorts is generally about one fifth of the quantity that is put into them, but at present a great deal of coke is used for that purpose.

A cast iron pipe D, called the hydraulic main, proceeds from the upper side of this cylinder to a cast iron receiver, which is situated at the bottom of the well in which the gasometer rises and falls; in this receiver the tar and other condensable products are collected, and are extracted from time to time by means of a pump affixed to it.

From the top of this receiver proceeds another iron pipe F, which reaches to the surface of the water in the well, but which is inserted into an airholder of about eighteen inches in diameter, and two feet long, made of iron. The lower part of this air-holder is pierced with holes, which serve a double purpose-first, to divide the gas into several small streams, and thus to render it purer by washing it as it passes through the water; and, secondly, it serves as a reservoir of gas, from whence the tar receiver, connecting tubes, and even the retort itself, may be filled with gas whenever an absorption takes place, by the retort being cooled, or otherwise. The gas is discharged from this air-holder into the gasometer H, which is suspended over the well, and rises and falls therein, being balanced by two weights passing over pullies. This gasometer is made of wrought iron plates, luted in the seams, so as to be air-tight, and well painted both within and without: it has an iron pipe made fast in the centre by means of two sets of stays, one at the bottom of the gasometer, and the other at the top. An upright pipe, fixed in the centre of the well, passes up the central pipe of the gasometer when it is depressed in the well. The gas is pressed out of the gasometer through a row of holes at the very top of the central pipe, into that pipe, whence it passes into the centre pipe of the well, which is continued across the well, and up the side, and from thence is branched out to the lamps.

At an early period of the gas manufacture the average quantity of gas produced from a chaldron of coals was scarcely 10,000 cubic feet. Later improvements have produced no less than double the quantity, and as a common-sized gas burner consumes about six cubic feet per hour, a single chaldron of coals will supply a gas burner for 6,666 successive hours, or more than eight months, without intermission. Besides this valuable and abundant production of gas, it yields other materials no less valuable and useful: it will yield one chaldron and a quarter of coke, worth nearly as much as the origi nal coals; also, twelve gallons of tar, saleable at as many shillings, and eighteen gallons of ammoniacal liquor, worth nine shillings, and which, by combina. tion with lime, furnishes the subcarbonate of ammonia, or the smelling salts of commerce.

Although artificial heat is necessary to decompose coals, so rapidly as to make their constituent principles available for the purposes of public utility and individual comfort, yet they appear to undergo a natural decomposition, and evolve gas in such abundance, as to endanger the lives of the miners, for carburetted hydrogen is but another name for fire-damp, the dreadful effects of which we have so often reason

to deplore, and of which so terrific an example has so lately and so unhappily occurred, as the public papers have recorded.

THE THERMOMETER.

Few instruments are more generally useful than the one which forms the subject of the following article: to it we are indebted for every accurate idea relative to temperature. I shall not enter into any detailed account of the invention of the thermometer, but proceed at once to notice it in its perfect state. To construct a thermometer a uniform capillary tube must be selected, having one extremity blown into a bulb; the operator taking such a tube, holds it in the flame of a spirit-lamp, when the air being rarified in consequence of its expansion, he dexterously inserts the open end in a vessel containing the fluid metal mercury; as the air in the tube cools, it contracts, and the mercury rises from the pressure of the atmosphere; the next process is to boil the metal in the tube, by which much of it is expelled, together with all the air, and during the ebullition the open end must be hermetically sealed. It is convenient to leave the tube for some time before we graduate it, as it is found that the atmosphere exercising a pressure on the sides of the bulb causes a slight variation in its capacity. In graduating we must first obtain certain points to start from; for which purpose, plunge the thermometer bulb into boiling water (with certain precautions which will be alluded to,) and note carefully the point to which the mercury rises; this is called the boiling point. The next step is to obtain a freezing point, which is done by substituting melting ice for boiling water. These fixed points being obtained, nothing remains to be done but to form a scale for the instrument; in this country the scale of Fahrenheit is the one generally employed: Fahrenheit's division is very far from being philosophical, and is much inferior to that of Celsius (the Centigrade) which is used on the Continent; the zero on the former scale is 32° and the space from the freezing to the boiling point is divided into 180 degrees, consequently the boiling point is 212°:* it is conjectured that Fahrenheit obtained his zero from a mixture of snow and salt; it would be of great advantage if the Centigrade scale were adopted in England; however, any division must be merely conventional, for we know nothing of the extremes of temperature; as Professor Graham beautifully expresses himself; "the scale of temperature may be compared to a chain, extending both upwards and downwards beyond our sight; we fix upon a particular link, and count upwards and downwards from that link, and not from the beginning of the chain."

It may be asked what proofs we have that the dilatations of mercury indicate corresponding increments of temperature; the answer to this question involves several important facts; the dilatations and contractions of solids by changes of temperature are too small to admit of any precision in recognizing them; while on the other hand gases are exactly the reverse liquids being intermediate between these two conditions of matter, it is found convenient to use them in the common thermometer, and of all liquids none are so well adapted as the metal mercury for measuring variations of temperature within

:

The Centigrade scale is, as the name implies, divided into 100 degrees. To reduce Centigrade to Fahrenheit, multiply by 9, divide by 5, and add 32; for as 180:9::100:5. Beaumur's thermometer, used in the North of Germany has 80 degrees, which may be reduced by an analogous process.

certain limits; the reasons for this are as follow.First. the expansions of mercury are proportional, and bear an exact relation to the heat which produces them, and we may prove this by the following simple experiment:-take two parts of water, one at 60° and the other at 100°; on mixing them, the mean temperature should be 80°, and when we test this by the aid of the thermometer we find such to be the case: if the mercury rose above 80°, it would indicate that it followed a progressively increasing rate of expansion, and would consequently unfit it for the instrument, the very principle of which depends on the fact that the dilatations of mercury are proportional to the intensity of the heat which produces them. Second, the specific heat of mercury is very small, being only 33 compared to water as 1000, hence it has the property of being quickly heated and cooled, a circumstance which imparts great sensibility to the instrument. Third, the increments of temperature are available from-39°+ the point at which mercury freezes to 600°, when it rises in vapour and thus affects the indications, though it does not boil till 662, though at very high temperatures mercury does expand at a progressively increasing rate, any inconvenience which might arise from this is obviated by the circumstance that glass is subject to the same law to a similar extent; so that the relative capacity between the mercury and the glass remained unaltered; the expansion of the one neutralizing the expansion of the other. The thin capillary tube is a beautifully devised measure, as it permits the slightest variation to be noted.

The most important circumstances to be attended to in graduating thermometers are to have the freezing and boiling points determined with scrupulous accuracy; while aetermining the latter, two circumstances must be attended to; first, that the barometer stands at 29.8 inches, as for every inch of variation the boiling point of water varies 1.76 degree; and, secondly, that the water be pure, and boiling in a metallic vessel, for it is found that this fluid boils at a higher temperature in glass or earthen vessels than it does in metallic ones;-to prove this, take some water in a glass flask, which has just ceased boiling, if we drop in some iron filings ebullition is immediately resumed. The only precaution to be observed in determining the zero is, that the ice or snow be melting; for it is a remarkable fact that water may be cooled down 20 degrees below the freezing point without congelation being determined; hence it is that the melting of ice and not the freezing of water which takes place invariably at 32°. Such is the philosophy of the simple but useful instrument we have now considered. I have described rather how a thermometer, may be made than how it is made; but anybody following the dis rections may construct one, and having once determined the fixed points to which I have so fully alluded, nothing is easier than to apply a scale to the instrument, which scale may be divided into any number of degrees.

W. PRESTON.

DIFFERENCE BETWEEN ANIMALS
AND VEGETABLES.

WHEN We compare together those animals and vegetables which are considered as occupying the highest stations in each Kingdom, we perceive that they

+-39° is 71o below the freezing point of water. Degrees below the ascending scale are indicated by the minus sign prefixed to them.