March 5, 1903 J 



NA TURE 



427 



high illuminating power, and even such practically minded 

 men as the late Sir Edward Frankland clamoured for the 

 introduction of high illuminating power gas, such as is 

 produced from cannel, in place of sixteen-candle coal gas, 

 the general line of argument being well shown by portions 

 of Sir Edward Frankland's introduction to the section of 

 his published researches dealing with applied chemistry, in 

 which such paragraphs as the following occur : — 



" Coal gas is not suitable for use in dwelling houses by 

 reason of its very low illuminating power — ioo cubic feet of 

 coal gas containing only 4 cubic feet of illuminating gas ; 

 the rest is mere rubbish, which heats and pollutes the air 

 in which the gas is consumed. ... It cannot be too widely 

 known that coal gas, although it costs less per 1000 cubic 

 feet, is, light for light, much dearer than cannel gas." ' 



Even now, when altered circumstances make a high- 

 power gas an anything but desirable and economical supply, 

 there are not wanting advocates who, undaunted, or perhaps 

 ignorant of the practical side of the question, still try to 

 holster up the old idea. 



It was in the latter part of the 'eighties that the lot of 

 the worried manager was made even harder by the rise in 

 price taking place in cannel coal, on which, up to that time, 

 he had entirely relied in admixture with ordinary gas coal 

 to give those higher grades of illumination demanded by 

 the fashion of the time, and which, although it ruined his 

 •coke, yet proved an efficient and trustworthy servant. 



This increase in price became so serious that in 1889 the 

 Gas Light and Coke Company commenced experiments 

 which led to the introduction of carburetted water gas in 

 place of cannel as an enricher, this process proving itself a 

 most valuable addition to the manufacture of coal gas, and 

 rapidly gaining favour and popularity, not only as giving 

 an easy means of raising the candle power of poor coal gas, 

 Ibut also as a stand-by in case of any sudden calls upon the 

 production power of the works. 



About this same period also, another method of enrich- 

 ment was introduced, which consisted of adding to gas 

 which did not fulfil the Parliamentary requirements the 

 vapours of such highly volatile hydrocarbons as petroleum 

 spirit and benzol, which, on account of their high illumin- 

 ating value, gave the necessary increase in the candle power 

 by the addition of an amount of vapour not likely afterwards 

 to recondense from the gas. 



Whilst these changes were taking place in gas manufac- 

 ture, rivals which seemed to threaten its very existence had 

 forced their way to the front, and with the electric light 

 largely used by the rich, and petroleum reduced to a price 

 at which even the poorest could afford its use as an illu- 

 minant, the field of utility seemed to be rapidly disappearing 

 from beneath the feet of the gas industry. However, when 

 things were looking their blackest, there slowly struggled 

 into prominence and commercial success a factor which at 

 ■once restored gas to its position of primary importance. 



It was in 1885 that the researches of Dr. Auer von Wels- 

 bach culminated in the production of the incandescent 

 mantle, which, frail and unsatisfactory in its earlier forms, 

 was gradually so improved in composition and manufacture 

 that by 1S92 it became a brilliant commercial success, and 

 placed in the hands of the gas industry a weapon which 

 rendered its position unassailable in competition with 

 electricity. 



Looked at from a common-sense point of view, the incan- 

 descent mantle will be seen to be merely a method of enrich- 

 ment. Instead of increasing the illuminating power of a 

 flame by crowding into the gas more and more hydro- 

 carbons, which during combustion are capable of separ- 

 ating carbon particles, the incandescence of which would 

 increase the amount of light emitted by the flame, and pro 

 rata the amount of heating and vitiation, with the mantle 

 you charge the flame with incombustible particles of far 

 greater light emissivity than the carbon possesses, and they 

 do their work without that increase in the temperature and 

 fouling of the atmosphere inseparable from the other pro- 

 cesses. It is the introduction of the incandescent mantle 

 and the improvements which are possible in its construction 

 which really give the possibilities to the gas of the future. 



Taking the enriched gas as supplied during the 'nineties, 



1 Frankland's " Experimental Researches in Pure, Applied and Physical 

 Chemistry,'* 1S77, p. 488. 



the light which can be obtained from it is entirely dependent 

 upon the burner in which it is consumed. This may be 

 stated as follows : — ■ 



Light emitted per cubic foot of sixteen-candle gas consumed. 



Burner. Candle units. 



Incandescent — high pressure ... ... 301035 



,, Kern ... ... ... 20 to 25 



„ ordinary ... ... ... 14 to 19 



Regenerative ... ... ... ... ... 7 to 10 



Standard Argand ... ... ... ... 3-20 



Ordinary Argand ... ... ... ... 2*90 



Union jet flat flame No. 7 ... 2*44 



6 2-15 



5 187 



4 ■■■ 174 



3 1 "63 



,, 2 ... ... . . I"22 



I 0-85 



° CC59 



In considering the value given to the gas by these burners, 

 It is seen that, according to the method by which it is burnt, 

 the consumer may obtain anything from thirty-five candles 

 down to less than one candle per cubic foot of gas. It must 

 also be borne in mind that the burners employed in these 

 tests were all good, well-made burners, giving the best duty 

 that can be obtained from them, whilst an examination of 

 burners used in consumers' houses shows that in most cases 

 any antiquated and corroded burner is considered good 

 enough at which to burn the gas, and the very people who 

 are loudest in their complaints as to the quality of the gas 

 are those who mo'st disregard the method of its consumption. 

 England is far behind Germany in the use of incandescent 

 lighting, and an inquiry made into the uses to which the 

 coal gas supply of a large town was put gave the following 

 result : — 



Per cent. 

 Incandescent lighting — private... ... ... 1200 



„ public ... ... ... 6*25 



Cooking ... ... ... ... ... . 2265 



Gas engines ... ... ... ... ... 6'6o 



Used in other ways ... ... ... ... 5250 



So that 47.5 per cent, is used for purposes in which illumin- 

 ating power is of no use and calorific effect is the one 

 important factor. 



It is also seen that 18.25 per cent, of the total gas made 

 is used for incandescent lighting, and this represents about 

 23 per cent, of the gas used for illuminating purposes, as 

 against 90 per cent, used in this way in Germany. 



This 23 per cent, thus used gives for a consumption of five 

 cubic feet not less than seventy candles, whilst the average 

 light obtained by the combustion of the remaining 77 per 

 cent, is 8.5 candles. 



It is quite clear that under such conditions as these the 

 supply of gas of a high candle power is simply waste of 

 money, and it is manifestly unfair that the consumer of 

 average intelligence, who is willing to utilise the benefits 

 given by the incandescent mantle, should have to pay for a 

 quality of gas only rendered necessary by the inertia of those 

 who decline to march with the times. 



Coal gas is daily being used more and more as a fuel, 

 and although the slight diminution of calorific value which 

 must of necessity accompany a lowered illuminating value is 

 a slight drawback, yet in practice any desired temperature 

 can be attained by a slightly larger consumption. Also a 

 cheapening of the gas would induce many to adopt it as a 

 fuel, this in turn tending to level up the load in production, 

 and so to render more economies possible. 



Everything clearly points in one direction, and that is, 

 that the future of coal gas is entirely dependent upon a 

 plentiful supply of low-grade gas — low grade from the point 

 of view that it should only have an illuminating value of 

 ten to twelve candles, that its heating value shall be as 

 high as can be practically attained and that its price shall 

 be as low as is consistent with the interests of the consumers 

 as well as of the shareholders in the gas industry. 



Already the stream has set in in this direction, and the 



NO. 174O, VOL. 67] 



