Gas (Economy Of, For Domestic Purposes). In situations where gas is to be obtained, it forms a ready, and, for some purposes, very economical means of obtaining heat; its economy does not arise from its cheapness compared with other means, but from the fact that it need not be lighted till the instant it is required, and can be as quickly extinguished when it has done its required duty. For heating any vessels containing liquids, especially if the heat is required to be only of short continuance, gas will be found extremely advantageous; aring-burner, constructed as shown in fig. 1, less than three inches in diameter, will quickly boil a gallon of water in a metallic vessel. Burners of this description are usually used in the laboratory, surrounded by a case made of sheet-iron or tinned plate, as fig. 2. This serves to support the vessel to be heated, to steady the jets of flame, and to conduct every portion of hot air against the bottom; the door also gives a ready access to the burner for the purpose of lighting the gas.

For the domestic use of gas in heating, there is no contrivance so useful as the following: a circular hole, from two to four or more inches in diameter, is cut in the dresser, through which is passed a sheetiron tube, supported by three little elbows. This tube projects a few inches above the table, and about a foot and a-half below; its lower end is open, and into it projects a gas-pipe, furnished with a stop-cock; the upper extremity is covered with a sheet of wire gauze, similar to that used for blinds,on which, as shown in tig. 3, may be placed some pieces of pumice-stone, surrounded and kept together by a broad ring - neither the pumice-stone nor the ring, however, are essential parts of the contrivance. The action of this arrangement is as follows : - When the gas is turned on it escapes from the pipe, rising through the tube, and mixing with the air contained within it; this mixture then escapes through the wire gauze, and may be lighted on its upper side, without passing through it to the gas below. The name should be perfectly free from smoke, which indicates too much gas - should be pale, colourless, and not soil any bright metal placed in it. If the flame is in the slightest degree yellow, it will do this, and then the gas should be partly turned off; on the contrary, if there is not enough gas, the flame will be extinguished. When lighted, the pumice becomes red-hot, and throws out a great heat When used in boiling, the vessel should be supported a short distance over the flame by a trevet; if it is made to rest on the top of the ring, and is sufficiently large to close it entirely, the current is Stopped and the flame extinguished, whilst the unburned gas still escapes below. This contrivance is most useful, it is lighted in an instant, is perfectly free from smoke, and no unburnned gas escapes; it throws out great heat; and may be employed to heat bright tools with much more convenience than a charcoal fire. The objections to its use are, that, in burning, it produces, as all gas does, a quantity of carbonic acid gas, deteriorating the air, and that the flame cannot be very much enlarged or diminished ; so that if fires of different power are required, two or more of the contrivances must be put in order. Otherwise, the instantaneous action, small cost, great heating power, and cleanliness of the plan, strongly recommend it. In summer weather, in many small families, it can be made to dispense altogether with the use of a fire. By a little variation, the whole contrivance may be made to stand on the table like fig. 1. In this and other cases, vulcanized India-rubber will be found to form by far the best kind of flexible tube, being quite impervious, very durable, and excessively pliant. Those who wish to try the experiment of heating on this plan may readily do so by covering the top of the glass chimney of any common burner with a piece of wire gauze, folding it over the sides; the gas may then be turned on, and lighted above the gauze, after it has mingled with the air in the chimney; a small burner, however, does not afford sufficient gas for the purpose, and, there being too much air, the flame is weak and liable to go out.

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