Read Ebook: The Boy's Playbook of Science Including the Various Manipulations and Arrangements of Chemical and Philosophical Apparatus Required for the Successful Performance of Scientific Experiments in Illustration of the Elementary Branches of Chemistry and Natura by Pepper John Henry

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Lavoisier's experiment may be repeated by passing into a measured jar, graduated into five equal volumes, four measures of nitrogen and one measure of oxygen; a glass plate should then be slid over the mouth of the vessel, and it may be turned up and down gently for some little time to mix the two gases, and when the mixture is tested with a lighted taper, it is found neither to increase nor diminish the illuminating power and the taper burns as it would do in atmospheric air.

HYDROGEN.

Hydrogen , so termed by Lavoisier--called by other chemists inflammable air, and phlogiston. Symbol, H; combining properties, 1. The lightest known form of matter.

Hydrogen is prepared in a very simple manner, by placing some zinc cuttings in a bottle, to which is attached a cork and pewter or bent glass tube, and pouring upon the metal some dilute sulphuric or hydrochloric acid. Effervescence and ebullition take place, and the gas escapes in large quantities, water being decomposed; the oxygen passes to the zinc, and forms oxide of zinc, and this uniting with the sulphuric acid forms sulphate of zinc, which may be obtained after the escape of the hydrogen by evaporation and crystallization.

In nearly all the processes employed for the generation of hydrogen gas, a metal is usually employed, and this fact has suggested the notion that hydrogen may possibly be a metal, although it is the lightest known form of matter; and it will be observed in all the succeeding experiments that a metallic substance will be employed to take away the oxygen and displace the hydrogen.

Whenever hydrogen is prepared it should be allowed to escape from the generating vessel for a few minutes before any flame is applied, in order that the atmospheric air may be expelled. The most serious accidents have occurred from carelessness in this respect, as a mixture of hydrogen and air is explosive, and the more dangerous when it takes fire in any closed glass bottle.

Thus, by the metals zinc, tin, potassium, red-hot iron , the oxygen of water is removed and hydrogen gas liberated.

A bell rung in a gas jar containing air emits a very different sound from that which is produced in one full of hydrogen--a simple experiment is easily performed by passing a jar containing hydrogen over a self-acting bell, such as is used for telegraphic purposes.

Some of the small pipes from an organ may be made to emit the most curious sounds by passing heavy and light gases through them; in these experiments bags containing the gases should be employed, which may drive air, oxygen, carbonic acid, or hydrogen, through the organ pipes at precisely the same pressure.

One of those toys called "The Squeaking Toy" affords another and ridiculous example of the effect of hydrogen on sound, when it is used in a jar containing this gas.

An accordion played in a large receptacle containing hydrogen gas demonstrates still more clearly what would be the effect of an orchestra shut up in a room containing a mixture of a considerable portion of hydrogen with air, as the former, like nitrogen, is not a poison, and only kills in the absence of oxygen gas.

Some very amusing experiments with balloons have been devised by Mr. Darby, the eminent firework manufacturer, by which they are made to carry signals of three kinds, and thus the motive or ascending power may be utilized to a certain extent.

The chief points requiring attention are:--first, the quality of the silk; secondly, the precision and scrupulous nicety required in cutting out and joining the gores; thirdly, the application of a good varnish to fill up the pores of the silk, which must be insoluble in water, and sufficiently elastic not to crack.

The varnish with which the silk is rendered air-tight can be made according to the private recipe of Mr. Graham, an aeronaut, who states that he uses for this purpose two gallons of linseed oil , two ditto , and four ounces of beeswax; the whole being simmered together for one hour, answers remarkably well, and the varnish is tough and not liable to crack.

For repairing holes in a balloon, Mr. Graham recommends a cement composed of two pounds of black resin and one pound of tallow, melted together, and applied on pieces of varnished silk to the apertures.

The actual cost of a balloon will be understood from information also derived from Mr. Graham. His celebrated "Victoria Balloon," which has passed through so many hairbreadth escapes, was sixty-five feet high, and thirty-eight feet in diameter in the broadest part; and the following articles were used in its construction:--

"An experiment in scientific ballooning, greater than has yet been undertaken, is about to be tried in this city. The project of crossing the Atlantic Ocean with an air-ship, long talked of, but never accomplished, has taken a shape so definite that the apparatus is already prepared and the aeronaut ready to undertake his task.

"The work has been conducted quietly, in the immediate vicinity of New York, since the opening of spring. The new air-ship, which has been christened the City of New York, is so nearly completed, that but few essentials of detail are wanting to enable the projectors to bring it visibly before the public.

"The aeronaut in charge is Mr. T. S. C. Lowe, a New Hampshire man, who has made thirty-six balloon ascensions.

"The dimensions of the City of New York so far exceed those of any balloon previously constructed, that the bare fact of its existence is notable. Briefly, for so large a subject, the following are the dimensions:--Greatest diameter, 130 feet; transverse diameter, 104 feet; height, from valve to boat, 350 feet; weight, with outfit, 3 1/2 tons; lifting power , 22 1/2 tons; capacity of gas envelope, 725,000 cubic feet.

"The City of New York, therefore, is nearly five times larger than the largest balloon ever before built. Its form is that of the usual perpendicular gas-receiver, with basket and lifeboat attached.

"Six thousand yards of twilled cloth have been used in the construction of the envelope. Reduced to feet, the actual measurement of this material is 54,000 feet--or nearly 11 miles. Seventeen of Wheeler and Wilson's sewing machines have been employed to connect the pieces, and the upper extremity of the envelope, intended to receive the gas-valve, is of triple thickness, strengthened with heavy brown linen, and sewed in triple seams. The pressure being greatest at this point, extraordinary power of resistance is requisite. It is asserted that 100 women, sewing constantly for two years, could not have accomplished this work, which measures by miles. The material is stout and the stitching stouter.

"The varnish applied to this envelope is a composition the secret of which rests with Mr. Lowe. Three or four coatings are applied, in order to prevent leakage of the gas.

"The netting which surrounds the envelope is a stout cord, manufactured from flax expressly for the purpose. Its aggregate strength is equal to a resistance of 160 tons, each cord being capable of sustaining a weight of 400 lbs. or 500 lbs.

"The basket which is to be suspended immediately below the balloon is made of rattan, is 20 feet in circumference and 4 feet deep. Its form is circular, and it is surrounded by canvas. This car will carry the aeronauts. It is warmed by a lime-stove, an invention of Mr. O. A. Gager, by whom it was presented to Mr. Lowe. A lime-stove is a new feature in air voyages. It is claimed that it will furnish heat without fire, and is intended for a warming apparatus only. The stove is 1 1/2 feet high, and 2 feet square. Mr. Lowe states that he is so well convinced of the utility of this contrivance, that he conceives it to be possible to ascend to a region where water will freeze, and yet keep himself from freezing. This is to be tested.

"Dropping below the basket is a metallic lifeboat, in which is placed an Ericsson engine. Captain Ericsson's invention is therefore to be tried in mid-air. Its particular purpose is the control of a propeller, rigged upon the principle of the screw, by which it is proposed to obtain a regulating power. The application of the mechanical power is ingeniously devised. The propeller is fixed in the bow of the lifeboat, projecting at an angle of about forty-five degrees. From a wheel at the extremity twenty fans radiate. Each of these fans is 5 feet in length, widening gradually from the point of contact with the screw to the extremity, where the width of each is 1 1/2 feet. Mr. Lowe claims that by the application of these mechanical contrivances his air-ship can be readily raised or lowered, to seek different currents of air; that they will give him ample steerage way, and that they will prevent the rotatory motion of the machine. In applying the principle of the fan, he does not claim any new discovery, but simply a practical development of the theory advanced by other aeronauts, and partially reduced to practice by Charles Green, the celebrated English aeronaut.

"The air-ship will carry weight. Its cubical contents of 725,000 feet of gas suffice to lift a weight of 22 1/2 tons. With outfit complete its own weight will be 3 1/2 tons. With this weight 19 tons of lifting power remain, and there is accordingly room for as many passengers as will care to take the venture. We understand, however, that the company is limited to eight or ten. Mr. Lowe provides sand for ballast, regards his chances of salvation as exceedingly favourable, places implicit faith in the strength of his netting, the power of his machinery, and the buoyancy of his lifeboat, and altogether considers himself secure from the hazard of disaster. If he accomplish his voyage in safety, he will have done more than any air navigator has yet ventured to undertake. If he fail, the enterprise sinks the snug sum of 20,000 dollars. Wealthy men who are his backers, sharing his own enthusiasm, declare failure impossible, and invite a patient public to wait and see."

The bill distributor consists of a long piece of wood, to which are attached a number of hollow fuses, with packets of bills, protected from being burned or singed by a thin tin plate; 10,000 or 20,000 bills can thus be delivered, and the wind assists in scattering them, whilst the balloon travels over a distance of many miles. It must be recollected that in each case the shells and the bills are detached by the string burning away as the fire creeps up from the fuse.

Over and over again the most excellent histories have been written of aerostation, but they all tend to one truth, and that is, the great danger and risk of such excursions; and to enable our readers to form their own judgment, a chronological list of some of the most celebrated aeronauts, &c., is appended.

Of the 41 persons enumerated, 14 were killed, and nearly all the aeronauts met with accidents which might have proved fatal.

Soap bubbles blown with hydrogen gas ascend with great rapidity, and break against the ceiling; if interrupted in their course with a lighted taper they burn with a slight yellow colour and dull report.

In a soup-plate place some strong soap and water; then blow out a number of bubbles with a mixture of oxygen and hydrogen; a loud report occurs on the application of flame, and if the room is small the window should be placed open, as the concussion of the air is likely to break the glass.

Any noise repeated at least thirty-two times in a second produces a musical sound, and by producing a number of small explosions of hydrogen gas inside glass tubes of various sizes, the most peculiar sounds are obtained. The hydrogen flame should be extremely small, and the glass tubes held over it may be of all lengths and diameters; a trial only will determine whether they are fit for the purpose or not.

Flowers, figures, or other designs, may be drawn upon silk with a solution of nitrate of silver, and the whole being moistened with water, is exposed to the action of hydrogen gas, which removes the oxygen from the silver, and reduces it to the metallic state.

In like manner designs drawn with a solution of chloride of gold are produced in the metallic state by exposure to the action of hydrogen gas. Chloride of tin, usually termed muriate of tin, may also be reduced in a similar manner, care being taken in these experiments that the fabric upon which the letters, figures, or designs are painted with the metallic solution be kept quite damp whilst exposed to the hydrogen gas.

A mixture of two volumes of hydrogen with one volume of oxygen explodes with great violence, and produces two volumes of steam, which condense against the sides of the strong glass vessel, in which the experiment may be made, in the form of water. As the apparatus called the Cavendish bottle, by which this experiment only may be safely performed, is somewhat expensive, and requires the use of an air-pump, gas jars with stop-cocks, and an electrical machine and Leyden jar, other and more simple means may be adopted to show the combination of oxygen and hydrogen, and formation of water.

If a little alcohol is placed in a cup and set on fire, whilst an empty cold gas jar is held over the flame, an abundant deposition of moisture takes place from the combustion of the hydrogen of the spirits of wine. Alcohol contains six combining properties of hydrogen, with four of charcoal and two of oxygen. If a lighted candle, or an oil, camphine, Belmontine, or gas flame, is placed under a proper condenser, large quantities of water are obtained by the combustion of these substances.

During the combustion of a mixture of two volumes of hydrogen with one of oxygen, an enormous amount of heat is produced, which is usefully applied in the arrangement of the oxy-hydrogen blowpipe. The flame of the mixed gases produces little or no light, but when directed on various metals contained in a small hole made in a fire brick, a most intense light is obtained from the combustion of the metals, which is variously coloured, according to the nature of the substances employed. With cast-iron the most vivid scintillations are obtained, particularly if after having fused and boiled the cast-iron with the jet of the two gases, one of them, viz., the hydrogen, is turned off, and the oxygen only directed upon the fused ball of iron, then the carbon of the iron burns with great rapidity, the little globule is enveloped in a shower of sparks, and the whole affords an excellent notion of the principle of Bessemer's patent method of converting cast-iron at once into pure malleable iron, or by stopping short of the full combustion of carbon, into cast-steel.

In the oxy-hydrogen blowpipe usually employed, the gases are kept quite separate, either in gasometers or gas bags, and are conveyed by distinct pipes to a jet of very simple construction, devised by the late Professor Daniell, where they mix in very small volumes, and are burnt at once at the mouth of the jet.

The gases are stored either in copper gasometers or in air-tight bags of Macintosh cloth, capable of containing from four to six cubic feet of gas, and provided with pressure boards. The boards are loaded with two or three fifty-six pound weights to force out the gas with sufficient pressure, and of course must be equally weighted; if any change of weight is made, the stop-cocks should be turned off and the light put out, as the most disastrous results have occurred from carelessness in this respect.

The oxy-hydrogen jet is further varied in construction by receiving the gases from separate reservoirs, and allowing them to mix in the upper part of the jet, which is provided with a safety tube filled with circular pieces of wire gauze. With this arrangement a most intense light is produced, called the Drummond or lime light, and coal gas is now usually substituted for hydrogen.

There are many circumstances that will cause the union of oxygen and hydrogen, which, if confined by themselves in a glass vessel, may be preserved for any length of time without change; but if some powdered glass, or any other finely-divided substance with sharp points, is introduced into the mixed gases at a temperature not exceeding 660? Fahrenheit, then the gases silently unite and form water.

There is a current of electricity passing from and between two platinum plates decomposing water, offering the converse of the Dobereiner experiment, and highly suggestive of the probability of the theory already advanced in explanation of the singular combination of oxygen and hydrogen in the presence of clean platinum foil, and more especially when we consider the operation of Grove's gas battery, in which a current of electricity is produced by pieces of platinum foil covered with finely-divided platinum, called platinum black; each piece is contained in a separate glass tube filled alternately with oxygen and hydrogen, and by connecting a great number of these tubes a current of electricity is obtained, whilst the oxygen and hydrogen are slowly absorbed and disappear, having combined and formed water, although placed in separate glass tubes.

The analysis of water is shown very perfectly on the screen by fitting up some very small tubes and platinum wires in the same manner as shown in fig. 125. The vessel in which the tubes and wires are contained with the dilute sulphuric acid must be small, and arranged so as to pass nicely into the space usually filled by the picture in an ordinary magic lantern, or, still better, in one lighted by the oxy-hydrogen or lime light. If the dilute acid is coloured with a little solution of indigo, the gradual displacement of the fluid by the production of the two gases is very perfectly developed on the screen when the small voltaic battery is attached to the apparatus; and of course a large number of persons may watch the experiment at the same time.

The author tried this lamp at Ryde, and although the coast-guards objected to the production of a brilliant light at night, which they stated might be mistaken for a signal and would cause some confusion amongst the war vessels in the immediate neighbourhood, enough experiments were made, to show that the Ward lamp would burn for a considerable time under water, and could be kept charged with the gas by means of a process that was easily workable in the boat. The gases were taken out mixed in gas bags, and pumped into the reservoir when required. With a much larger reservoir greater results could be obtained; and if nautilus diving bells are to be used in modern warfare, they will require a powerful light to show them their prey, so that they may attach the explosives which are to blow great holes in the men-of-war.

CHLORINE, IODINE, BROMINE, FLUORINE.

Chlorine . Symbol, Cl. Combining proportion, 35.5. Specific gravity, 2.44. Scheele termed it dephlogisticated muriatic acid; Lavoisier, oxymuriatic acid; Davy, chlorine.

As Scheele first indicated, chlorine is obtained by the action of the black oxide of manganese, on "the Spirit of Salt," or hydrochloric acid; and the most elementary and instructive experiment showing its preparation can be made in the following manner:--

The mode of preparing chlorine, as already given, though very instructive, is troublesome to perform; a more simple process may therefore be described:--

Pour some strong hydrochloric acid upon powdered black oxide of manganese contained in a Florence oil-flask, taking care that the whole of the black powder is wetted with the acid so that none of it clings to the bottom of the flask in the dry state to cause the glass to crack on the application of heat. A cork and bent glass tube is now attached, and conveyed to the pneumatic trough; on the application of heat to the mixture in the flask the chlorine is evolved, and may be collected in stoppered bottles, the first portion that escapes, although it contains atmospheric air, should be carefully collected in order to prevent any accident from inhaling the gas, and it will do very well to illustrate the bleaching power of the gas, and therefore need not be wasted. The above process may be described in symbols, all of which are easily deciphered by reference to the table of elements, page 86.

Another and still more expeditious mode of preparing a little chlorine, is by placing a small beaker glass, containing half an ounce of chlorinated lime, usually termed chloride of lime or bleaching powder, carefully at the bottom of a deep and large beaker glass, and then, by means of a tube and funnel, conveying to the chloride of lime some dilute oil of vitriol, composed of half acid and half water; effervescence immediately occurs from the escape of chlorine gas, and as it is produced it falls over the sides of the small beaker glass into the large one, when it may be distinguished by its green colour. If a little gas be dipped out with a very small beaker glass arranged as a bucket, and poured into a cylindrical glass containing some dilute solution of indigo, and shaken therewith, the colour disappears almost instantaneously; and if a piece of Dutch metal is thrown into the beaker glass it will take fire if enough chlorine has been generated, or some very finely-powdered antimony will demonstrate the same result. Thus, with a few beaker glasses, some chloride of lime, sulphuric acid, a solution of indigo, and a little Dutch metal, the chief properties of chlorine may be displayed.

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