Lundi 18 juillet 2011

The board must have a hole through it

Totnake experiments on the coal gas, procure a pistol barrel, or piece of gun barrel stopped at one end, which may be done with a lute made of clay and sand. About half fill the barrel with mineral coal in coarse powder, and pass it through a small fumace, or chaffing dish of charcoal, so as to heat it red hot. Connect with the open end of the barrel a tube of leaH, tin, or glass, leading under a vessel inverted, and filled with lime water. For this part of the apparatus, two small k. 3'j both of them open at one end will answer very welL Fill the largest of them with lime water, and having furnished the other with a stop-cock passing through the head, invert this into the other, and on opening the stop-cock so as to let off the air, it will sink down and fill with water. Wben it is full and all the air is forced out, turn the stop-cock and then having passed the tube which conveys the gas under it, make a lire in the furnace so as to heat the gun barrel red hot. The gas, will soon be driven over in abundance. To burn it, a piece of lead, tin, or brass tube may be fastened to the stopcock by soldering, or by means of melted bees wax and a strip of rag. The upper end of this tube being closed, make two or three fine orifices about the 6ize of pin holes around the tube. On turning the stop-cock and apply ing a lamp, the gas will burn with a beautiful white flame, the sight of which will amply repay the young chemist for the trouble of making the experiment.
To obtain carburetted hydrogen from alcohol hy means of sulphuric acid, mix together in a tubulated retort, one measure of alcohol and three measures of the acid. The alcohol is to be poured in first, and the acid mixed with it a little at a time, as a great degree of heat would be the consequence of mixing them suddenly. Connect with the retort a tube leading under the vessel, as described for obtaining the coal gas, and distil with a gentle heat.
This gas exceeds all otheis in the splendour and beauty of its flame.
482. This is also called gaseous oxide of carbon. It contains a less quantity of oxygen than carbonic acid, but is composed of the same elements.
483. Carbonic oxide is obtained by exposing carbonic acid to the action of some substance, which has the power of abstracting a part of its oxygen. This may be done by heating in an earthen retort or iron bottle, a mixture of equal parts of chalk and charcoal. Or by heating in the same way, equal parts of chalk and iron filings.
Obs. In both of these expii indents the result is the same. The carbonic acid being expelled from the chalk by the heat, the charcoal or iron filing, having a strong attraction for oxygen, absorbs a portion from the car bonic acid, and the consequence is, that carbonic oxide is formed; or in other words, the carbonic acid is changed into carbonic oxide by the loss of a portion of oxygen.
484. This gas may be received over water in the usual way, but if it is required in a state of purity, lime water must be used. The last product of the distillation is the purest gas.
485. This gas is lighter than common air. It is inflammable when fired from a small orifice, and burns with a blue flame.'
486. When burned in the manner which proves that hydrogen forms water by combustion, no water is formed which proves that it contains no hydrogen.
Oba. It is extremely noxious to animals, and fatal to them if confined in it.
487. This compound gas is composed of oxygen, and nitrogen.
It may be obtained by several processes ; but that of distilling the nitrate of ammonia is the only one which affords it in sufficient purity for respiration. For the method of making this salt, see nitrate of ammonia.
Exp. To prepare this gas and try its effects by respiration, the following simple apparatus may be used where no better can be obtained. Prepare a Florence flask by fitting to it a tube as in figure 6. Into this put two or three ounces of nitrate of ammonia. For a gas holder, fit to a large stone jug a cork pierced with two apertures by a burning iron. Into one of the apertures pass a tube of glass or tin, so that it shall come within half an inch of the bottom of the jug when the cork is put in its place; and let the other orifice be stopped with another cork. For a pneumatic tub, take a common wash tub, and fit to it a strip of board passing through the middle, and about three inches from the top, so that when the tub is filled with water the board will be covered. The board must have a hole through it, over which the mouth of the jug is to be set. Having prepared things as above directed, fill the jug with water and invert it over the aperture of the board ; bend the tube belonging to the flask so that it will just enter the mouth of the jug, and setting the flask on the lamp stand, apply a very gentle heat. If there is no lamp furnace at hand, the flask can be suspended by a string or wire, and heated by a common lamp, or two. The salt will soon melt and become fluid, and the gas will he extricated in abundance. When the jug is nearly full, which can be told by the noise of the hubbies, slip the hand under its mouth and set it upright; then immediately put the cork with the tube , through it in its place. Having prepared the gas, let it stand over the water which remains in the jug for an hour or two, shaking it now and then, so that if it should contain any nitrous gas, this may be absorbed.


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Par laoke23 - 0 commentaire(s)le 18 juillet 2011

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