instantly extinguished in it a little below the brim) take another jar of rather a smaller size, and place at the bottom of it a lighted taper or a small animal, and pour the invisible contents of the first jar into the second (in the same manner as if water was poured) the candle will be immediately extinguished, or the animal will die; though the eye is incapable of perceiving any thing poured upon them capable of producing this effect.

EXPERIMENT V.

Carbonic acid gas is absorbable by water.

(See Appendix No. 24.)

Fill a jar partly with this gas, and let it stand for some hours over water; an absorption will gradually take place, till at last none of the gas remains. If this be repeated, with this difference, that the jar be shaken strongly, a very rapid diminution will take place.

REMARK....Water may be charged with upwards of three times its own bulk of carbonic acid gas, if pressure be applied. The water thus impregnated has a very brisk and pleasant taste. Various kinds of apparatus are employed for this purpose. A machine has been invented by Dr. Nooth, and improved by Parker and Magellan, which is convenient and ingenious; but it is impossible. to impregnate water by its means with more than half its own bulk of carbonic acid gas. The valve of this machine is the most defective, and renders it extremely apt to break for the capillary tube does not admit the air through it, unless there be a considerable quantity condensed in the lower vessel, and the condensation is apt to burst the ves

Other apparatus, more simple, have been invented by different persons, descriptions of which may be found in Scherer's Journal der Chimie; in the Transactions of the Manchester Philosophical Society; and in Bouillon La Grange's Manual of Chemistry, vol. I. p. 93.

Cider, perry, ale, champaign, &c. owe their briskness to the carbonic acid gas which they contain, and which becomes rapidly disengaged in order to assume the gaseous form, on removing the cork of the bottle; it is this also which produces froth, &c.

EXPERIMENT VI.

Carbonic acid gas when combined with water possesses acid properties.

This may be shown by dipping into water saturated with carbonic acid gas a piece of litmus paper, or by mixing with it about an equal quantity of infusion of cabbage. The blue colour of the paper or infusion will be changed to red.

EXPERIMENT VII.

Carbonic acid gas precipitates lime, barytic, and strontia

water.

Let the stream of carbonic acid gas, as it proceeds from the disengaging vessel, pass into either of these solutions, the fluid, though perfectly transparent before, will instantly grow turbid, and carbonate of lime, barytes, or strontia, will be formed.

If equal measures of water impregnated with carbonic acid gas, and either of the above solutions be mixed, a similar effect will be produced.

EXPERIMENT VIII.

Carbonic acid gas exerts powerful effects on living vegetables.

Water impregnated with carbonic acid gas proves highly nutritive, when applied to the roots of plants. But, on the contrary, carbonic acid gas applied as an atmosphere, by confining living vegetables in it, proves injurious to the health of the plants, especially in the shade.

This may be proved by confining a small plant in a vessel filled with the gas. The plant will soon decay and

die.

RATIONALE....In the first case, where water is present, the carbonic acid is decomposed, the carbonaceous principle fixes itself into the vegetable, becoming a component part of it, the oxygen which held the carbon in solution is therefore disengaged in a gaseous state. In the latter instance no such effect takes place.

EXPERIMENT IX.

Carbonie acid gas is rapidly absorbed by alkalies, and alkaline earths.

Fill a tube with this gas over water, and when full invert it in a cup containing a concentrated solution of potash, or any other alkali; the solution will rise in the tube, and if the gas be very pure will fill it entirely.

RATIONALE....This absorption of the gas is owing to the alkali uniting with the carbonic acid gas, and forming with it a saline compound, called carbonate of potash.*

It unites and forms neutral salts with the alkalies, the alkaline earths and most metals. T. C.

LIGHT

CARBONATED HYDROGEN GAS.

PART XX.

SECT. I.

It was mentioned before that hydrogen gas has the property of dissolving various substances in minute quantities, such as carbon, sulphur, phosphorus, &c. The nature of the gas now under consideration furnishes an instance of this kind. Light carbonated hydrogen gas is hydrogen gas holding charcoal in solution. There are several combinations of this kind of gas obtained by different processes, which differ in their properties, and in the proportion of their constituent principles.

PROPERTIES OF LIGHT CARBONATED HYDROGEN GAS.

Light carbonated hydrogen gas has a fetid odour. It is neither absorbed nor altered by water. It is inflammable, and burns with a denser and deeper coloured flame than hydrogen gas. It is unalterable by acids or alkalies, and by water. Its specific gravity is greater than that of hydrogen gas, or that of common air. Its combustion with a due proportion of oxygen gas is productive of water and carbonic acid. When passed through melted sulphur, it becomes converted into sulphurated hydrogen gas, and charcoal is deposited. Electrization dilates it permanently to a little more than twice its original bulk. The air thus

expanded requires a greater quantity of oxygen to decompose it than the same quantity of gas not dilated by electricity; 100 cubic inches of pure carbonated hydrogen gas weigh from 16 to 21 grains.

METHODS OF OBTAINING LIGHT CARBONATED HYDROGEN GAS.

Light carbonated hydrogen gas may be obtained from animal, vegetable, or mineral substances. Nature produces it ready formed in marshes and ditches, on the surface of putrid water, in burying places, common sewers, and in those situations where putrid animal and vegetable matters are accumulated. It is also generated in the intestinal canal of living animals.

1. Light carbonated hydrogen gas may be plentifully procured from most stagnant waters: to do this fill a wide mouthed bottle with the water, and keep it inverted therein, with a funnel in its neck: then with a stick stir the mud at the bottom just under the funnel in the bottle, so as to let the bubbles of air which rise from the mud enter into the bottle; when, by thus stirring the mud in various places, and catching the air in the bottle, it is filled, it must be corked under water.

2. It may also be obtained during the distillation of animal and vegetable matters. For instance,

Let shavings of wood or saw-dust be put into a retort, and begin the distillation with a gentle heat, increasing it gradually till the retort becomes red hot; a great quantity of gas will be liberated, which may he caught over water.* On examining this gas, it will be found to consist of carbonic acid gas and carbonated hydrogen gas. In order to obtain the latter in a state of purity, the whole must be mixed with lime water, or with a caustic alkaline solution. The carbonic acid gas will be absorbed, and the carbonated hydrogen gas left behind in a pure state.

RATIONALE....The production of this gas in this manner is the result of a partial analysis of the wood: it proves that wood contains solid hydrogen, carbon, and oxygen. When the intensity of the heat has reached a certain degree, a part of the charcoal unites with part of the oxygen, and produces carbonic acid, which by means of

*

I procured 12 quarts of gas from 4 ounces of pine saw dust; and about 19 quarts from 4 ounces of Liverpool coal. T. C.