portions, and mixing only one part of oxygen gas with two of hydrogen. The report will then be much louder than with common air.

This experiment may be made conveniently by means of an apparatus called the inflammable air pistol. To charge it, nothing more is necessary than to introduce its mouth inverted into a wide-mouthed bottle, filled with a mixture of oxygen and hydrogen gas, leaving it in for a few seconds; it is then to be stopped with a cork, and may be fired by the electrical spark taken from the prime conductor of the machine, or by a charged Leyden phial.

It has been, with great plausibility, conjectured, that the noise of thunder is the effect of the rapid combustion of hydrogen and oxygen gas, fired by the electric spark; and that the rain which falls so copiously at the time of thunder-storms, is owing to a sudden formation of water by this means.

From its lightness, it has been employed for making air-balloons, which have been already described.

Soap bubbles, filled with hydrogen gas, ascend in the air. To show this, fill a bladder with hydrogen gas, and fasten it to a tobacco-pipe; dip the bowl of the pipe into a lather of soap, squeeze the bladder gently, in order to form a bubble, and detach it in the usual manner. These bubbles will rise rapidly into the air: if a lighted taper be presented to them, they catch fire and burn with a slight explosion.

If the bladder be filled with a mixture of hydrogen and common air, the soap-bubbles will ascend, and when the taper is presented to them they will explode with a loud report. This experiment is more striking if oxygen gas be mixed with hydrogen. If the bladder be squeezed so as to

form a great many bubbles on the surface of the bason, the report will be as loud as that of a cannon.

It has lately been discovered, that hydrogen, like oxygen, is an acidifying principle. United to chlorine, it forms hydro-chloric acid, which is the same as muriatic acid. Combined with iodine, it forms hydriodic acid.

When hydrogen gas is united to sulphur, it forms sulphureted hydrogen, which has also the properties of an acid. Tellureted hydrogen has also acid properties.

Hydrogen and Oxygen.

It has been already mentioned, that these two elements, when combined, form water.

Till lately, water was considered as a simple substance, or element; no one had ever been able to decompose it; and the decomposition of it, which is daily effected in natural processes, had escaped observation. We shall, however, give such evident proofs of the decomposition and recomposition of water, as will clearly show that it is not a simple body.

Experiment I.-A tube of common glass E F (Plate 2. fig. 7.), well annealed, and difficult to be fused, about ten or eleven lines diameter, was placed across a furnace CFED, in a position somewhat inclined; and to its upper extremity was adapted a glass retort A, containing a known quantity of distilled water, and resting on a furnace VV. To the lower extremity of the glass tube F was applied a worm SS, connected with the double-tubulated flask H, and to the other tubulure was adapted a bent glass tube K K, destined to convey the gas to an apparatus proper for determining

the quality and quantity of it. When the whole was thus arranged, a fire was kindled in the furnace CFED, and maintained in such a manner, as to bring the glass tube E F to a red heat, but without fusing it; at the same time as much fire was maintained in the furnace V V X X, as to keep the water in the retort A in a continual state of ebullition,

In proportion as the water in the retort A assumed the state of vapour by ebullition, it filled the interior part of the tube E F, and expelled the atmospheric air which was evacuated by the worm SS, and the tube K K. The steam of the water was afterwards condensed by cooling in the worm SS, and fell drop by drop, in the state of water, into the tubulated flask H. When the whole of the water in the retort A was evaporated, and the liquor in the vessels had been suffered to drain off completely, there was found in the flask H a quantity of water, exactly equal to that which was in the retort A, and there had been no disengagement of any gas; so that this operation was merely a common distillation, which gave absolutely the same result as if the water had never been brought to a state of incandescence, in passing through the glass tube E F.

Experiment II.-Every thing being arranged as in the preceding experiment, twenty-eight grains of charcoal reduced to particles of a moderate size, and which had been previously exposed for a long time to a white heat in close vessels, were introduced into the glass tube E F. The operation was then conducted as before, and the water in the retort A kept in a continual state of ebullition, till it was totally evaporated.

The water in the retort A was distilled as in the

preceding experiment, and being condensed in the worm SS, had fallen drop by drop into the flask H; but at the same time there had been disengaged a considerable quantity of gas, which escaped through the tube K K, and was collected in a proper apparatus. When the operation was finished, there was found nothing in the tube E F but a few ashes, and the twenty-eight grains of charcoal had totally disappeared.

The gases disengaged were found to weigh altogether 113.7 grains. There were found two dif ferent kinds of gas, viz. 114 cubic inches of carbonic acid gas, weighing 100 grains, and 380 cubic inches of a very light gas, weighing 13.7 grains. This last gas took fire, on being applied to a lighted body in contact with the air. In examining afterwards the weight of the water which had passed into the flask, it was found less than that in the retort A by 85.7 grains. In this experiment, therefore, 85.7 grains of water and 28 grains of charcoal formed carbonic acid gas equal to 100 grains, and a peculiar gas susceptible of inflammation, equal to 13.7 grains. To form 100 grains of carbonic acid gas, 72 grains of oxygen must be united to 28 grains of charcoal or carbon. The 28 grains of charcoal put into the glass-tube EF, took, therefore, from the water, 72 grains of oxygen, since there was formed carbonic acid equal to 100 grains. It appears, then, that 85.7 grains of water are composed of 72 grains of oxygen, and 13.7 grains of a substance forming the base of a gas susceptible of inflammation. The following is a proof of it.

The apparatus being arranged as above, instead of the 28 grains of charcoal, 274 grains of thin shavings of iron, rolled up in a spiral form, were

introduced into the tube EF; the tube was then brought to a red heat as before; and, in the same manner, the whole of the water in the retort A was made to evaporate.

In this experiment there was disengaged only one kind of gas, which was inflammable; there was obtained of it about 406 cubic inches, weighing 15 grains.

The 274 grains of iron put into the tube E F were found to weigh 85 grains above what they did when introduced; and the water first employed was diminished 100 grains.

The volume of these iron shavings was found to be greatly enlarged. The iron was scarcely any longer susceptible of attraction by the magnet; it dissolved without effervescence in acids; in a word, it was in the state of a black oxyd, like that which has been burned in oxygen gas.

In this experiment there was a real oxydation of the iron by the water, entirely similar to that effected in the air by the aid of heat. 100 grains of water were decomposed; and of these 100 grains, 85 united to the iron, to reduce it to the state of black oxyd; these 85 grains, therefore, consisted of oxygen; the remaining 15 grains, combined with caloric, formed inflammable gas. It thence follows, that water is composed of oxygen and the base inflammable gas, in the proportion of 85 to 15, or of 17 to 3.

If it be true, as we have endeavoured to prove, that water is composed of hydrogen combined with oxygen, it thence results, that, by re-uniting these principles, water ought to be produced. This, indeed, is what takes place when, into a vessel filled with oxygen, a stream of hydrogen is introduced