158 



Olefiant gi\s cannot of course be em- 

 ployetl for any economical purposes, 

 and is only here adverted to for the 

 sake of comparison. The relation of 

 the quantity of oil-gas to that of coal- 

 gas, furnishes a datum that may be 

 practically useful, especially as indi- 

 cating; the relative sizes of gasometers 

 required for the supply of establish- 

 ments. It may, I tliiuk, be stated with 

 sufhcient accuracy for practical pur- 

 poses, that a gasometer containing 1000 

 cubical feet of oil-gas, is adequate to 

 furnish the sanve quantity of light as 

 one of ;^000 cubical feet of coal-gas, 

 provided due attention be paid to the 

 construction of the bnrners, and to the 

 distribution of (ho lights. 



For llie ordinary purposes of illumi- 

 nation by oil-gas, I consider ten-hole 

 Argaud burners, each consuming about 

 a cubical foot and a half per hour, and 

 giving the light of seven wax caudles, 

 or nearly two oil Argands, as (lie most 

 economical and generally useful. Single 

 jet burners, or tiiose in which the flames 

 do not coalesce, consume, as has been 

 above siiown, a very much larger quan- 

 tity of gas for the ])roduction of an equal 

 quantity of ligiit ; and for the same 

 reason, Argand burners, in wliich the 

 flames do not coalesce, consume more 

 gas for an equal pro.luction of light, 

 tUan those in which the apertures are 

 more numerous, but sufficiently near 

 eacli other to allow of the union of the 

 separate flames. 



To ascertain the relative heating 

 powers of the flames of olefiant oil, and 

 coal gases, I employed the twelve-hole 

 Argand burneis mentioned above, and 

 placed over each, as near to the lamp 

 glass as was consistent with a clear 

 flame, a clean copper boiler, 2,5 inches 

 deep and .') inches diameter, slightly 

 concave at bottom, capable of holding 

 rather more (lian a (jTiart of water, \\ith 

 an immersed thermometer, and a small 

 veut forsteam. It contained two pounds 

 of distilled w.ater, which was raised to 

 the boiling point in similar times, 

 namely, 20' by each of the flames ; so 

 that it wonld appear, that to raise a 

 quart of water from 50° to 212", at 30 

 inches barometrical pressure, requires 

 870 cubical inches of olefiant gas, 

 1300 - - - oil-gas, 



2100 - - • coal-gas. 



From this experiment it may be 

 inferred, that the air of a room equally 



The Royal Society of London. 



March 1, 



lighted by oil and coal gas, will be 

 much less heated by the former than 

 the latter; but that the actual heating 

 power of the flames is in tiie direct 

 ratio of the quantity of olefiant gas. 



Having occasion in some of the fore- 

 going experiments to produce light of 

 great brilliancy by the combustion of 

 olefiant gas, and finding it iery difficult 

 to measure its intensity by a comparison 

 of shadows, in (he manner pointed out 

 by Count Hum ford, I endeavoured to 

 avail myself of Mr. Leslie's photome- 

 ter: for this purpose I concentrated 

 the light by a plano-convex lens, and 

 placed the blackened ball of the instru- 

 ment in the focus. I found the eft'ect, 

 however, so great as to lead me to be- 

 lieve that I hatl obtained a focus of 

 considerable heating power, and on sub- 

 stituting a delicate mercurial thermo- 

 meter, it rose 4",4 in 5'. In the focus 

 tluis obtained from the light of a large 

 Argand burner supplied with olefiant 

 gas, the elevation of temperature was 

 very sensible to the hand; and in 

 depressing and elevating the flame by 

 means of a regulating stop-cock, cor- 

 responding effects were produced u]iou 

 the thermometer : the lens itself, which 

 was a thick one, did not become heated. 



To this paper is annexed a drawing 

 of an Argand burner for oil-gas, upon 

 what Mr. Brande believes to be the 

 most economical construction. It dif- 

 fers from the common gas Argands, in 

 having the top of the cylinders joined, 

 not by a flat perforated plate, but by 

 two bevilled rims, ascending from the 

 inner and outer tube respectively, and 

 joining each other at nearly a right 

 angle, the sharp angle being taken off 

 a little on the upper part, so as to make 

 a flat face for the holes. The bevilling 

 of the perforated edge contributes 

 greatly to the perfection of the light. The 

 diameter of the circle of holes is 0,7 

 inch, and the holes siiould not be more 

 than J, of an inch in diameter ; eon- 

 snming at the highest average 4000 

 cubical inches per hour, it gives the 

 light of between eight and nine wax 

 candles of four to the pound. 



What is technically termed a rose- 

 burner has six holes of the same dimen- 

 sions as those of the Argand ; and when 

 so regulated as to produce a light equal 

 to that of six wax candles, its greatest 

 aveiage consumption of gas amounts to 

 4800 cubical inches per hour. 



VARIETIES 



