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. 2_; 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 is consequently too much air, and the flame is weak and liable to go out. [Illustration: _Fig. 4._] We cannot conclude this article on heat, without entering our most earnest protest against _all_ those injurious contrivances for burning charcoal without a flue; the use of charcoal-braziers in a large kitchen is not to be recommended, but a charcoal stove in a dwelling-room is most objectionable. Charcoal, in burning, produces carbonic acid gas, an invisible and therefore insidious poison, which is so deadly in its effects, that if the air of a room contains but one-tenth of its bulk, the breathing of it for a short time is fatal. Every pound of charcoal, in burning, produces more than three pounds and a half of this deadly gas, and the ill effect of charcoal stoves may be readily imagined. In Paris, in the years 1834 and 1835, there were 360 cases resulting from the fumes of charcoal, of which more than 260 were fatal. In order to test the effects of these stoves, Mr. Coathupe, of Wraxall, shut himself up in a close room containing eighty cubic yards of air, with one of them in action. In four hours he was seized with giddiness, which, in an hour’s time, became most intense; he then had the desire to vomit, but not the power; this was followed by an utter loss of strength, throbbing at the temples, and agonizing headache, but no sense of suffocation; finding that the experiment was becoming dangerous, he essayed to open the window, but had the greatest difficulty in so doing; and when his wife came into the room, he was found in a speechless state, in which he remained for some time.