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Description of a new Stove for burning Pitcoal, and

consuming all its Smoke.

READ AT A MEETING OF THE AMERICAN PHILOSOPHICAL SOCIETY,

JANUARY 28th, 1786.

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TOWARDS the end of the last century an ingenious French philosopher, whose name I am sorry I cannot recollect, exhibited an experiment to show, that very offensive things might be burnt in the middle of a chamber, such as woollen rags, feathers, &c., without creating the least smoke or smell. The machine in which it was made, if I remember right, was of this form, (Plate XV. Fig. 1,) made of plate iron. Some clear burning charcoals were put into the opening of the short tube A, and supported there by the grate B. The air, as soon as the tubes grew warm, would ascend in the longer leg C and go out at D, consequently air must enter at A descending to B. In this course it must be heated by the burning coals through which it passed, and rise more forcibly in the longer tube, in proportion to its degree of heat or rarefaction, and length of that tube. For such a machine is a kind of inverted siphon; and, as the greater weight of water in the longer leg of a common siphon in descending is accompanied by an ascent of the same fluid in the shorter; so, in this inverted siphon, the greater quantity of levity of air in the longer leg, in rising is accompanied by the descent of air in the shorter. The things to be burned being laid on the hot coals at A, the smoke must descend through those coals, and be converted into flame, which, after destroying the offensive smell, came out at the end of the longer tube as mere heated air.

Whoever would repeat this experiment with success, must take care that the part A B, of the short tube, be

quite full of burning coals, so that no part of the smoke may descend and pass by them without going through them, and being converted into flame; and that the longer tube be so heated as that the current of ascending hot air is established in it before the things to be burnt are laid on the coals; otherwise there will be a disappointment.

It does not appear, either in the Memoirs of the Academy of Sciences, or Philosophical Transactions of the English Royal Society, that any improvement was ever made of this ingenious experiment, by applying it to useful purposes. But there is a German book, entitled Vulcanus Fumulans, by John George Leutmann, P. D., printed at Wirtemberg in 1723, which describes, among a great variety of other stoves for warming rooms, one, which seems to have been formed on the same principle, and probably from the hint thereby given, though the French experiment is not mentioned. This book being scarce, I have translated the chapter describing the stove, viz.

“ CHAPTER VII.

On a Stove, which draws downwards.

“Here follows the description of a sort of stove, which can easily be removed, and again replaced at pleasure. This drives the fire down under itself, and gives no smoke, but, however, a very unwholesome vapor.

“In the figure, A is an iron vessel like a funnel, (Plate XV. Fig. 20,) in diameter at the top about twelve inches, at the bottom near the grate about five inches; its height twelve inches. This is set on the barrel C, which is ten inches diameter and two feet long, closed at each end EE. From one end rises a pipe or flue about four inches diameter, on which other pieces of pipe are set, which are gradually contracted to D, where the opening is but about two inches. Those pipes must together be at least four feet high. B is an iron grate. FF are iron handles guarded with wood, by which the stove is to be lifted and moved. It stands on three legs. Care must be taken to stop well all the joints, that no smoke may leak through.

“When this stove is to be used, it must first be car- · ried into the kitchen and placed in the chimney near the fire. There burning wood must be laid and left upon

its grate till the barrel C'is warm, and the smoke no longer rises at A, but descends towards C. Then it is to be carried into the room which it is to warm. When once the barrel C is warm, fresh wood may be thrown into the vessel A as often as one pleases, the flame descends and without smoke, which is so consumed that only a vapor passes out at D.

“ As this vapor is unwholesome, and affects the head, one may be freed from it, by fixing in the wall of the room an inverted funnel, such as people use to hang over lamps, through which their smoke goes out as through a chimney. This funnel carries out all the vapor cleverly, so that one finds no inconvenience from it, even though the opening D be placed a span below the mouth of the said funnel G.. The neck of the funnel is better when made gradually bending, than if turned in a right angle.

“The cause of the draft downwards in the stove is the pressure of the outward air, which, falling into the vessel A in a column of twelve inches diameter, finds only a resisting passage at the grate B, of five inches, and one at D, of two inches, which are much too weak to drive it back again; besides, A stands much higher than B, and so the pressure on it is greater and more

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VOL. VI.

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forcible, and beats down the flame to that part where it finds the least resistance. Carrying the machine first to the kitchen fire for preparation is on this account, that in the beginning the fire and smoke nåturally ascend, till the air in the close barrel C is made thinner by the warmth. When that vessel is heated, the air in it is rarefied, and then all the smoke and fire descends linder it.

“The wood should be thoroughly dry, and cut into pieces five or six inches long, to fit it for being thrown into the funnel A.

It appears to me, by Mr. Leutmann's explanation of the operation of this machine, that he did not understand the principles of it, whence I conclude he was not the inventor of it; and by the description of it, wherein the opening at A is made so large, and the pipe E D, so short, I am persuaded he never made nor saw the experiment, for the first ought to be much smaller, and the last much higher, or it hardly will succeed. The carrying it in the kitchen, too, every time the fire should happen to be out, must be so troublesome, that it is not likely ever to have been in practice, and probably has never been shown but as a philosophical experiment. The funnel for conveying the vapor out of the room would besides have been uncertain in its operation, as a wind blowing against its mouth would drive the vapor back.

The stove I am about to describe was also formed on the idea given by the French experiment, and completely carried into execution before I had any knowledge of the German invention ; which I wonder should remain so many years in a country, where men are so ingenious in the management of fire, without receiving long since the improvements I have given it.

Description of the Parts. A, the bottom plate which lies flat upon the hearth, with its partitions, 1, 2, 3, 4, 5, 6, (Plate, Fig. 2) that are cast with it, and a groove Z Z, in which are to slide the bottom edges of the small plates Y, Y, figure 12; which plates meeting at X close the front.

B 1, figure 3, is the cover plate showing its under side, with the grooves 1, 2, 3, 4, 5, 6, to receive the top edges of the partitions that are fixed to the bottom plate. It shows also the grate W W, the bars of which are cast in the plate, and a groove V V, which comes right over the groove Z Z, figure 2, receiving the upper edges of the small sliding plates Y, Y, figure 12.

B 2, figure 4, shows the upper side of the same plate, with a square impression or groove for receiving the bottom mouldings TTİT of the three-sided box C, figure 5, which is cast in one piece.

D, figure 6, its cover, showing its under side with grooves to receive the upper edges Sss of the sides of C, figure 5, also a groove RR, which, when the cover is put on, comes right over another Q Q in C, figure 5, between which is to slide

E, figure 7, the front plate of the box.

P, a hole three inches diameter through the cover D, figure 6, over which hole stands the vase F, figure 8, which has a corresponding hole two inches diameter, through its bottom.

The top of the vase opens at 0 0 0, figure 8, and turns back upon a hinge behind, when coals are to be put in; the vase has a grate within at NN of cast iron H, figure 9, and a hole in the top, one and a half inches diameter, to admit air, and to receive the ornamental orass gilt flame M, figure 10, which stands in that

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