gallipot; and when this diluted acid is cold, pour it into the ale-glass, stir it with a piece of stick; and now, in addition to sulphate of soda, as in the last experiment, a portion of sulphate of lead is formed simultaneously with hydrochloric acid, but this acid is immediately de-hydrogenated by a part of the oxygen of the original oxide of lead; water is formed, and then Chlorine is truly educed, in the state of a yellow vapor which arises in the glass.

For the purpose of fumigation, the chemist generally prefers to educe Chlorine from a compound well known as "Chloride of Lime"-more correct would be the expression "Chlorinated Lime:" this compound has the invaluable property, when exposed to an infected atmosphere, of slowly evolving chlorine, which, mingling with mephitic matters, deprives them of virulence more effectually than even the action of nitric acid.

The simplest method of proceeding to fumigate a small apartment is to select ten or twelve earthenware flower-pans, and place in each of them six or eight ounces of chlorinated lime; then arrange these pans, some near the ceiling, others near, or upon the floor; then close the doors and windows, and leave all undisturbed for a day or two, in the course of which time the carbonic acid of the air will have expelled much of the chlorine from the compound; the windows of the apartment must then be opened from the outside, and fresh air allowed to sweep through previous to opening the door, for many persons are seriously affected by a very slight inhalation of chlorine; the chlorinated lime may be then stirred in the pans with a piece of stick, and again left shut up for a similar time.

The whole of the chlorinated lime may next be put

into one large deep pan, much larger than is sufficient to hold it; this is to be placed on the top of a pair of steps, so as to be near the ceiling, and then, having shut the windows, quickly pour about a quart of vinegar into the pan, and immediately quit the room, closely shutting the door.

The affusion of the vinegar will now liberate all the chlorine that the compound might yet contain, and after a day or two, the room may be entered with the above precautions, and the residue in the pan carefully thrown away.

In extensive fumigations, chlorine is generally evolved from a mixture of four pounds, by weight, of common salt, one pound of oxide of manganese, two pounds of sulphuric acid, and two of water; no precautions are required for mixing the two former, but great precautions are required as regards the two latter.

The water must be placed in an earthenware bowl, and then the sulphuric acid must be added in a very slender stream, the mixture of the two liquids being rapidly promoted by stirring them together with a flat piece of wood; it must then be allowed to cool before

use.

If sulphuric acid be plentifully and suddenly added to water, the heat evolved by the meeting of the two cold liquids is so great that it will inevitably break a glass vessel, and very likely one of earthenware-why is the heat evolved?

Because the water, which is the lightest liquid of the two, when it energetically combines with the sulphuric acid, has its density increased, and therefore its capacity for heat diminished in a far more remarkable degree than in the experiment with water and spirits of wine, as

detailed at page 115, and most dangerous accidents have happened to persons in ignorance of this fact.

The mixture of common salt and oxide of manganese must then be weighed into five portions of one pound each, and placed in as many quart or three pint earthenware basins upon the five topmost "treads" of a pair of steps set in the centre of the room, the windows being closed; then, with a half-pint jug dipped into the cold diluted acid, a quantity of it sufficient to fill about three parts of the jug must be baled out and poured upon the mixture contained in the uppermost of the pans, then a similar quantity upon that in the second, third, fourth, and fifth, as quickly as possible, the operator always taking care to avoid placing his face, either level with, or below the pans; this he can do by standing on another pair of steps, more elevated than the first, and placed close alongside; he must then quickly descend and quit the apartment, shutting and securing the door.

Should any chlorine be accidentally inhaled, the readiest means of alleviating the distressing coughing that it produces, is to saturate a lump of sugar with brandy, and a few drops of "sal volatile," and then to hold the sugar in the mouth until it dissolves.

The basins may remain for two days, then the windows of the apartment being opened from the outside, as already directed, when the odor of chlorine is no longer strongly perceptible, the apartment may be entered without danger, the basins removed, their exhausted contents thrown away, and then they may be again charged and arranged with all former precautions, and left for a similar time, and subsequently removed with the same careful observance.

The apartment may then be considered to have undergone a thorough fumigation, for neither infectious nor

contagious matter can insidiously lurk in the presence of chlorine.

The pans containing the "chlorinated lime," and the basins containing the mixture of which mention has been just made, are directed to be placed near the ceiling of the room, because the evolving chlorine is more than twice as heavy as the air, and therefore will descend and uniformly mingle with it, which is the grand object of the whole proceeding; if, however, the vessels were placed on the floor, the heavy chlorine would chiefly repose there as a distinct stratum, and not rapidly diffuse its powers throughout the main volume of the air.

The precaution to be observed by the operator, in proceeding quickly with the addition of the acid, and in keeping his head above, and not at or below the vessels, is, in the first place, that the evolution of chlorine may commence from all within a few seconds, and in the next, that he may avoid inhaling any portion of the descending poisonous element, for a poison it is, although applied for the destruction of another poison; if he can. hold his breath during the few seconds that are required for the addition of the acid and his descent from the steps, it will be so much the better.

The chemist, therefore, discovers an extraordinary fact in illustration of the power by which elements and compounds are controlled, viz., that chlorine in its pure uncombined state is a poison, and a destroyer of poison, whilst in combination with the metal sodium; it forms exactly sixty per cent. of the common salt, which is an absolute requisite of life, and a most powerful antiseptic of organic matters.

The yellow color of chlorine, its density, its power upon organic and inorganic bodies, may be demonstrated

by the following experiments, which should be made in the open air, that the deleterious vapor may be instantly wafted away.

Place two ounces of "chlorinated lime" in a pint widemouthed flint-glass bottle, then quickly add a fluid ounce of "hydrochloric acid ;" an evolution of chlorine will immediately ensue; it will expel the air from the bottle and supply its place with its own yellow vapor, which is now technically said to be the "atmosphere of the bottle;" the yellow will become yet more visible if a sheet of white paper be held behind one part of the bottle.

Immerse a few shreds of red cabbage leaves in a teacup half full of boiling water, and thus obtain a fine bluecolored infusion, which, when cold, pour into a tall halfpint ale-glass; then take the bottle containing the chlorine, and holding its mouth over that of the glass, as in the ordinary act of pouring, the heavy chlorine vapor will pour out like water, and not only display its color in the glass, but upon slight agitation it will instantly destroy that of the blue vegetable infusion.

If a piece of tainted meat be placed in a half pint widemouthed bottle, provided with a glass stopper, upon pouring chlorine into it, then closing it, and leaving the meat exposed to the vapor for half an hour, upon shaking it out the taint will be destroyed.

Twist a piece of thin copper bell-wire into a tolerably close spiral around a ruler, then place two leaves of "Dutch gold" (i. e., nearly pure copper), within this spiral; put half an ounce of "chlorinated lime" into a half pint ale-glass, add half a fluid ounce of hydrochloric acid, cover the mouth of the glass with a card until the chlorine appears deep yellow; then quickly remove the