$70 Dr Fyfe on the Illuminating power of Coal and Oil Gas , 
In stating the illuminating power, I have chosen Mr Milne's 
gas as a standard, because, when well prepared by his appara- 
tus, it is, I have been informed, of equal illuminating power 
with those made from oil, in the different oil-gas establishments 
in England, From a number of trials which have been made at 
the different manufactories, he has come to the conclusion, that 
a burner consuming one foot per hour, gives a light equal to 
that of eight candles (short sixes) burning with a clear flame, 
which is the same as that afforded by his gas, when w r ell pre- 
pared ; that is, containing 32 per cent, of olefiant, which is the 
highest I have found it to yield. 
With a view of confirming the accuracy of my conclusion 
with respect to the illuminating power of the gases, I have, in 
company with Mr Milne, compared them with the light afford- 
ed by candles ; and as the experiments were numerous, and 
conducted with every possible care, to secure a regularity in the 
consumption, I am inclined to place the greatest reliance in 
them, at least as far as we can trust to this mode of determin- 
ing it. The coal-gas, in all the trials, was that prepared from 
the mixed coal, and contained 15 of olefiant. The oil-gas was 
prepared from palm-oil, and contained 25 per cent. 
Coal-gas . — Exp. 1. — Argand burner. No. 1., with five holes, 
and a flame of 3 inches, consumed 2’25 feet per hour, giving a 
light equal to that of 8-62 candles (short sixes), burning with a 
clear flame ; 1 foot is therefore equal to 3'84 candles. 
Exp. 2 .-— Argand burner, No. 2., with ten holes, consumed 
per hour, with 3 inch flame, 3 feet, and gave a light equal to 
that of twenty candles ; 1 foot, therefore, equal to 66 candles. 
Oil-gas.— Exp. 3. — Argand burner, No. 1., with ten holes, 
consumed per hour, with 1| inch flame, 1 foot, giving a light 
equal to that of 6 -78 candles. 
Exp. 4.— -Argand burner, No. 2., with 14 holes, consumed 
per hour, T95 feet with If inch flame, the light being equal to 
that of 15 34 candles, that is, 1 foot equal to 7-8. 
Exp. 5. — Argand burner (of Glasgow), No. 1., with ten 
holes, consumed 1 foot per hour, flame If inch, the light being 
equal to that of 721 candles. 
The conclusion from the above experiments, taking each gas 
burning under the most favourable circumstances, is as 6.6 to 
