154 



NATURE 



\yune 1 6, 



minative power produced by the distillation of tlie coal did not 

 exceed 1-35 Carcel burner.-:, or I3'5 standard candles, accord- 

 ing to our English mode of measurement, the gas given off from 

 the end of the first quarter of an hour, during a period of two 

 hours, possessed an illuminating power of I'6l6 Carcel burners, 

 ori6'i6 standard candles. According to the figures given in 

 the valuable experiments of M. Ellissen, it appears that 

 nearly two-thirds of the total production of gas takes place 

 in the above period, whilst the remaining third is distilled 

 during the first quarter of an hour and the last hour and 

 three quarters. It hence follows that by changing the direc- 

 tion of the flow of gas at the periods indicated, allowing the 

 first results of distillation to flow into the heating gas-main, then 

 for two consecutive hours into the illuminating gas main, and for 

 the remainder of the period again into the heating gas-main, one- 

 third volume of heating and two-thirds of illuminating gas would 

 be obtained, with this important difference, that the illuminating 

 gas would be of i5'l6 instead of I3'5 candle power, and that 

 the heating gas, although possessed of an illuminating power of 

 only 1 1 '05, would be preferable to the mixed gas for heating 

 purposes, in being less liable to deposit soot in its combustion 

 upon heat-absorbing surface^, and in giving, weight for weight, a 

 calorific power superirjr to olefiant gas. 



These experiments not having been made for the particular 

 objects I have in view, no account was taken of the quantity or 

 quality of the gas coming from the retort during the first quarter 

 of an hour. Judging by the nature of the curves given by M. 

 Ellissen, it is reasonable to suppose that during the first quarter 

 of an hour a considerable quantity of gas of very inferior illu- 

 minating power is given off, which, if taken into account, « ould 

 still further improve the result given in favour of separating the 

 illuminating from the heating gases. 



It will be observed that although the candle-power of the 

 illuminating gas would be raised to only 16 '25 if two-thirds 

 of the gas were set apart for this purpose, i.e. after the first 25 

 minutes of distillation up to 2h. 3Sm. from the commencement 

 of the charge, a gas equal to 1 8 '04 candles would be obtained if 

 the proportionate quantity of heating and illuminating gas were 

 reversed, which might be effected by continuing the distillation 

 for illuminating purposes from o"2Sm. to ih. 27m. after the 

 commencenient of the charge, whilst if equal quantities of 

 heating and illuminating gas were produced, which would result 

 from allowing the illuminating gas to flow into its receiver from 

 0'25m. to 2h. om., the candle-power of this portion of the gas 

 would be raised to 167S candles, as shown in the figures given 

 below. 



Candle- 



Total gas produced from ton of coal. 



Illuminating gas passing into its main 

 25 minutes after commencement of 

 charge : — 



If two-thirds the quantity used for illu- 

 mination from oh. 25m. to 2h. 35m. 



If half the quantity used for illumina- 

 tion from oh. 25m. to 2h. om 



If one-third the quantity used for illu- 

 mination from oh. 25m. to ih. 27m... 



Cubic Feet. 



power. 



10573-20 of 13-50 



Illuminating Heati 

 Gas. 

 Cubic Candle- 

 Feet, power. 



Gas 

 Cubic 

 Feet. 



7048-8 

 5286-6 



16-25 3524-4 

 16-78 5286-6 



3524-4 18-04 7048 -s 



These important results are borne out by a series of photo- 

 graphic observations which were made some years ago by Mr. 

 Sugg, which Mr. Sugg has further supplemented verbally in 

 stating that the average illuminative power obtained by the dis- 

 tillation of Newcastle coal might be taken at 14 candle-power, 

 whilst two-lhiids of the quantity, if separated in the manner I 

 propose, would produce an average of 16 candles. 



The working out of this plan would involve the mechanical 

 operation of changing the direction of the gas coming from each 

 bench of retorts at the proper periods of the charge ; this could 

 be accomplished by means of a simple reversing valve similar to 

 that applied for many years in reversing the current of the 

 regenerative gas-furnace, and a sand-glass may be placed in 

 front of each bench of retorts for the guidance of the man in 

 charge as to the time when the reversal should be made. In 

 order to distribute the two gases a double set of gas-mains 

 would certainly be required ; but these exist already in the princi- 

 pal thoroughfares of many of our great towns, where at one 

 period or another competing gas companies have been esta- 



blished, and it would not be difficult, I think, to utilise these 

 services for the separate supply of illuminating and heating gas, 

 the latter being taken into such houses and establishments only 

 where asked for by the occupiers. 



The public could well affjrd to pay an inreased price for a 

 gas of greatly increased illuminating power, and the increase of 

 revenue thus produced would enable the gas companies to supply 

 heating gas at a proportionately reduced rate. It would not be 

 necessary to employ upon the heating gas the same expense and 

 trouble in purification as is required for illuminating gas, because 

 the products of combustion of the heating gas would not as a rule 

 enter the apartments, but be conducted into the atmosphere 

 through the ordinary chimneys. Heating the retorts by means 

 of the regenerative gas-fm-nace would, as already indicated, lead 

 to an increased production of gas from each bench of retorts, 

 and thus compensate for the reduced amount of illuminating gas 

 in each operation. The healing gas might without inconvenience 

 be sent through the pipes at a greater pressure than the illu- 

 minating ga^, in order to make a given plant of mains transmit 

 an increased quantity. 



The question may fairly be asked whether a demand would be 

 likely to arise for heating gas similar in amount to that for 

 illuminating gas, and I may state that I am decidedly of opinion 

 that although at the present moment the amount of gas supplied 

 for illuminating purposes exceeds that for heating, the diminu- 

 tion in price of the latter would very soon indeed reverse these 

 proportions. Already gas is used in rapidly increasing quantities 

 for kitcheners, for the working of gas-engines, and for fire-grates. 

 As regards the latter application, I may here mention that an 

 arrangement for using gas and coke jointly in an open fire-place, 

 combined with a simple contrivance (with a view of effecting the 

 combustion of the gas by heated air), has found favour with many 

 of the leading grate builders and with the public ; although this 

 arrangement was suggested by me only last winter, several 

 hundred of these grates are already in use in London, Man- 

 chester, Leeds, Glasgow, and other towns, showing how fully 

 alive the public are at the present time to that great crying evil, 

 "the smoke nuisance." 



It may be as well for me to mention here, that neither the 

 regenerative gas-coke fire-grate just alluded to, nor the plan I 

 here advocate of separating the produce of gas-retorts, has been 

 made by me subject-matter of letters patent, my time being 

 already too much occupied in other directions to give that 

 amount of constant attention to these subjects which the working 

 of a patent necessitates. 



As regards the use of illuminating gas, I have one more sugges- 

 tion to make which I feel confident will be viewed by you not 

 without interest. The illuminating effect produced in a gas 

 flame depends partly upon the amount of carbon developed in 

 the solid condition in the body of the flame, and partly upon 

 the temperature to which these particles are heated in the act of 

 combustion. Having already shown how by separation a gas of 

 greater luminosity may be supplied, it remains to be seen how 

 the temperature of combustion may be raised. This may be 

 effected to an extent that seems surprising by certain mechanical 

 arrangements, whereby a portion of the waste heat produced by 

 the flame itself is rendered available to heat the gas and air 

 sustaining the combustion of the flame, say to 600° F., or even 

 beyond that point. 



The arrangement I have adopted for this purpose is ref re- 

 sented on the sectional diagram, and I have also the pleasure to 

 place the burner itself before you to enable you to test its effi- 

 ciency by actual trial. The burner is of the ordinary Argand 

 type, mounted in a small cyhndrical chamber of sheet copper 

 connected with a vertical rod of copper projecting up and 

 through the centre of the burner, and terminating in a cup-like 

 exlen-ion at a point about four inches above the gas orifices, or 

 on a level with the top of the flame. A small mass of fire-clay 

 fills the cup, projecting upv\-ards from it in a rounded and pointed 

 form. The copper vessel surrounding the burner is contracted 

 at its upper extremity w ith a view of directing a current of air 

 against the gas jets on ihe burner, and on its circumference it is 

 perforated for the admission of atmospheric air. The bottom 

 surface is fcrmed of a perforated disk covered with wire gauze, 

 and wire gauze also surrounds the circumference of the perforated 

 cylinder. The external air is heated in passing through these 

 "regenerative" surfaces, and the flame is thus fed with air, 

 heated to the point above indicated, which by more elaborate 

 arrangements might be raised to a still higher degree. The ball 

 of fire-clay in the centre of the burner, which is heated to red- 



