.-,28 



NA TURE 



iFeb. 3, 1 88 1 



cheaply applied, that it will relieve our housemaids of the most 

 irksome portion of their daily work in layiag fires and cleaning 

 grates, and that a warm and cheerful fire can be made at a 

 considerably cheaper rate than when using coal, you will admit, 

 I hope, that the proposal is worthy of a trial. 



In outward appearance my fire-grate, which I have not made 

 the subject of a patent, and which may therefore be put up by 

 any grate or gas-fitter without restraint, is very similar to the 

 ordinary coal-grate ; the latter may indeed be converted into the 

 smokeless grate at a very trifling cost. The essential features of 

 this grate are that solid carbonaceous fuel, such as coke or 

 anthracite, are used in combination with as much gas as is found 

 necessary to raise the former to the point of incandescence, that 

 the combustion is entirely confined to the front of the grate, 

 whence radiation into the room takes place, and that any heat 

 reaching the back of the grate is conducted away and utilised in 

 heating the incoming ah, by which combubtion in front of grate 

 is supported ; in this way greater brilliancy and considerable 

 economy are realised. 



One arrangement by which this is effected is represented in 

 diagram i (see Nature, vol. xxiii. p. 26). The iron dead plate 

 c is riveted to a stout copper plate a faciiig the back of the fire- 

 grate, and extending five inches both upwards and downwards 

 from the point of junction. The dead plate c stops short about 

 an inch behind the bottom bar of the grate to make room for 

 a half-inch gas-pipe /J which is perforated with holes of about 

 one-sixteenth of an inch placed at distances of one and a half 

 inch along the inner side of its upper surface. This pipe rests 

 upon a lower platen/, which is bent downwards towards the back 

 so as to provide a vertical and horizontal channel of about one 

 inch in breadth between the two plates. A trap-door e, held up 

 by a spring, is provided for the discharge of ashes falling into 

 this channel. The vertical portion of this channel is occupied 

 by a strip of sheet copper about four inches deep, bent in and 

 out like a lady's frill and riveted to the copper back piece. 

 Copper being an excellent conductor of heat, and this piece 

 presenting (if not less than a quarter of an inch thick) a con- 

 siderable sectional conductive area, transfers the heat from the 

 back of the grate to the frill-work in the vertical channel. An 

 air current is set up by this heat, which, in passing along the 

 horizontal channel, impinges on the line of gas flames and 

 greatly increases their brilliancy. So great is the heat imparted 

 to the air by this simple arrangement that a piece of lead of about 

 half a pound in weight introduced through the trap-door into 

 this channel melted in five minutes, proving a temperature ex- 

 ceeding 619' F. or 326" C. The abstraction of heat from the 

 back has moreover the advantage of retarding the combustion 

 of the coke there while promoting it at the front of the grate. 



The sketch represents a fire-place at my ofiice, in a room of 

 72CO cubic feet capacity facing the north. I always found it 

 difiicult during cold weather to keep this room at 60° F. with a 

 coal fire, but it has been easily maintained at that temperature 

 since the grate has been altered to the gas-coke grate just 

 described. 



In order to test the question of economy. I have passed the 

 gas consumed in the grate through a Parkinson's lo-light dry 

 gas-meter ; the coke used is also carefully weighed. 

 _ The result of one day's campaign of nine hours is a consump- 

 tion of 62 cubic feet of gas and '22 lbs. of coke (the coke re- 

 maining in the grate being in each case put to the debit of the 

 following day). Taking the gas at the average London price of 

 3^-. (>ii. per 1000 cubic feet, and the coke at lS:r, a ton, the 

 account stands thus for nine hours : — 



(/. 



62 cubic feet of gas at 3^. 61/. per thousand 2-604 



22 lbs. coke at 1 8.f. a ton 2'i2i 



Total 



4725 



or at the rate of o-525(/. per hour. In its former condition as a 

 coal-grate the consumption exceeded generally two and a half 

 large scuttles a day, \\eighing 19 lbs. each, or 47 lbs. of coal, 

 which at 23^. a ton equals 5 -jd. for nine hours, being o'633rf. 

 per hour. This result shows that the coke-gas fire, as here 

 described, is not only a warmer but a cheaper fii-e than its pre- 

 decessor ; with the advantages in its favour that it is lit without 

 the trouble of laying the fire, as it is called, and keeps alight 

 without requiring to be stirred, that it is thoroughly smokeless, 

 and that the gas can be put off or on at any moment, which in 

 most cases means considerable economy. 



A second and more economical arrangement as regards first 

 cost is shown in diagram 2 (Nature, vol. xxiii., pp. 92, 93), 

 and consists of two parts, which are simply added to the existing 

 grate, viz. : (i) the gaspipe </with a single row of holes of 

 about ^ inch diameter, 1-5 inch apart along the upper side 

 inclining inward, and (2) an angular plate a, of cast iron, with 

 projecting ribs /', extending from front to back on its under side, 

 presenting a considerable surface, and serving the purpose of 

 providing the heating surface produced by the copper plate and 

 frill-work in my first arrangement. In using iron instead of 

 copper it is nece sary however to increase the thickness of these 

 plates and ribs in the inverse ratio of the conductivity of 

 the two metals, or as regards the back plate, from \ inch to J 

 inch according to the best determinations recently published by 

 Sir W. Thomson. This thickness would be practically incon- 

 venient, and in order to avoid it the construction of the grate 

 had to be modified for cast iron. 



An inclined plate fastened to the lower grate bar directs the 

 incoming air upon the heating surfaces and provides at the same 

 time a support for the angular and ribbed plate, which is simply 

 dropped into its firm position between it and the back of the 

 grate. 



The front edge of the horizontal plate has vandyked openings 

 c, forming a narrow grating, through which the small quantity 

 of ashes that will be produced by combustion of the coke or 

 anthracite in the front part of the grate discharge themselves 

 down the incline towards the back of the heart'-', where an open 

 ash-pan may he placed for their reception. 



In adapting the arrangement to existing grates, the ordinary 

 grating may be retained to support the angular plate, which has 

 in that case its lower ribs cut short, to the level of the horizontal 

 grate. 



But it may be asked, Are you sure that the coke and gas grate 

 you advocate will do away with fogs and smoke? My answer 

 is, that it would certainly do away with smoke, because the pro- 

 ducts of combustion passing away into the chimney are perfectly 

 transparent. Mr. Aitken has, however, lately proved in an 

 interesting paper read before the Royal Society of Edinburgh, 

 that even with perfect combustion a microscopic dust is sent up 

 into the atmosphere, each particle of which may form a mole- 

 cule of fog. We have evidence, indeed, that the whole universe 

 is filled with dust, and this is, according to Prof. Tyndall, a 

 fortunate chcumstance, for without dust we should not have a 

 blue, but a pitch-black sky, and on our earth we should be, ac- 

 cording to Mr. Aitken, without rain, and should have to live in 

 a perpetual vapour bath. The gas fires would contribute, it 

 appears, to this invisible dust, and w-e should, no doubt, continue 

 to have fogs, but these would be ^^■hite fog , which would not 

 choke and blacken us. It is not clearly shown what this fine 

 dust, resulting from the combustion of gas, consists of, and it 

 seems reasonable to suppose that in perfect combustion it will 

 be avoided. 



Granted the cure of smoke, it might still be questioned 

 whether such a plan as here proposed could be carried out on 

 so large a scale as to affect our atmosphere with the existing 

 mains and other plant of the gasworks. If gas were to be de- 

 pended upon entirely for the production of the necessary heat, as 

 is the case with an ordinary gas and asbestos grate, it could 

 easily be proved that the existing gas mains would not go far to 

 supply the demand ; each grate would consume from 50 to 100 

 cubic feet an hour, representing in each hou^e a consumption 

 exceeding many times the supply to the gaslights. My experi- 

 ments prove, however, that an average consumption of from 6 to 

 8 cubic feet of gas per hour suffices to work a coke gas grate on 

 the plan here proposed. This is about the consumption of a 

 large Argand burner, and therefore within the limits of ordinary 

 supply. 



But independently of the practical question of supply, it is 

 desirable on the score of economy to rely upon the solid carbon 

 chiefly for the production of radiant heat for the following 

 reason ; — 



1000 cubic feet of ordinary illuminating gas weigh 34 lbs., 

 and the heat developed in their combustion amounts to 

 34 X 22,000 = 748,000 heat units. 



One pound of solid coke develops in combustion, say, 13,400 

 heat units (assuming 8 per cent, of incombustible admixture), 



and it requires 



748,000 

 1,400 



56 lbs., or just half a hundredweight, 



of this coke to produce the same heating effect as 1000 cubic 

 feet of gas. But 1000 cubic feet of gas cost on an average 



