

Different Kinds of Coal for the purpose of Illumination. 163 



sumption and the pressure, so that, by taking the average of 

 many trials, an accurate result may be obtained. Having fixed 

 on the jet 40, bushed with platinum, and furnished with the scale 

 for the flame, and with the pressure-gauge, I found, by numerous 

 trials, that the time for the consumption of 1 foot of a gas, was 

 64' 41", the flame being 5 inches. The pressure at the burner- 

 gauge was }||ths. The specific gravity of the gas was, by ex- 

 periment in the usual way, found to be 602-6, at 60°, and barom- 

 eter 30 j of course one foot requiring 64 / 41", then in 60', there are 

 consumed 0*927 of a foot. Thus, then, the consumptions being, 

 in equal times, as the square roots of the pressures, and the times, 

 for equal consumptions being inversely as the square roots, while 

 the specific gravities are also inversely as the square roots of the 

 pressures, the following table will give the consumption of gases 

 in 60 minutes, the time for the consumption of a foot ; and the 

 specific gravity, at 60°, and barometer 30, calculated from the 

 square roots of the pressures, the gases being consumed, with a 

 flame of 5 inches from the jet 40 ; taking, as 1 have already stated, 

 a gas of specific gravity 602-6, burning under a pressure of fifths, 

 1 foot in 64' 41" ; the square root of pressure 117 being 108166. 

 Should any other jet be found preferable, the quantity of gas 

 consumed by it, with a flame of a fixed height, must be ascer- 

 tained by repeated trials, with an accurate experimental metre; 

 taking the pressure accurately each time. The average consump- 

 tion and pressure being thus fixed on, the specific gravity is to be 

 taken by experiment in the usual way ; then the consumptions 

 and specific gravity of other gases, with the same burner and 

 height of flame, will be found, as already directed, with jet 40 ; 



3.UQ for tvlii/»h fho tnhlo Vioo Koon fr»nctrnr»tp(l 



Table, shewing the Times for Equal Consumptions, the Consumptions 



in Equal Times, and the Specific Gravities of Gases, requiring the 



following Pressures to burn them, from Jet 40, with a b-inch Flame. 



Pressure 

 in lOOtl.s 

 of inch. 



60 

 61 



62 



6:? 

 64 

 65 



66 



67 



68 

 6 



70 

 71 



78 



73 



74 



1 foot bums 10pth 3 of 



min ,,,ot ,n 



/ 



// 





90 



18 



666 



89 



36 



66-9 



88 



48 



675 



88 



10 



68-n 



87 



28 



68-:» 



86 



48 



69-1 



m 



8 



696 



85 



30 



701 



-4 



48 



70-6 



84 



15 



710 



83 



36 



71-7 



83 







72-2 



82 



30 



726 



81 



54 



732 



81 



21 



73-7 



Specific 

 Graviti 

 Air- 1000. 



841 4 

 834-5 

 827-7 

 821-2 



SI4-7 



808-4 



802- a 



796'A 



790-4 

 779*0 



77*5 



768- 1 



762-8 

 757-8 



Pressure. 



7-". 



76 

 77 



78 



79 



80 



81 

 82 

 83 



-1 



85 



*A 



87 

 - 

 89 



1 foot burns 



mill. 



80 

 80 

 79 

 79 



78 

 78 

 77 

 77 



76 

 76 

 75 

 75 

 75 

 74 

 74 



// 



48 

 16 



lOOtlis of 



foot iti 



60 mins. 



Specific 

 Gravities, 



Air,= ]000. 



711 

 74 5 



752 6 

 747- 



45 



751 



74 2-8 



14 



7.V7 



738-3 



44 



76:* 



733 3 



12 



76-7 



728 7 



42 



772 



7>4-3 



12 



77-7 



719 3 



48 



78 1 



7 1 5-4 



12 



7-7 



7111 



54 



791 



7D6-9 



24 



7!>-5 



702-8 







80-0 



6f)8«8 



36 



80-4 



6. M0 



6 



809 



690-9 



