234 Dr Fyfe on the Illuminating Power of Coal-Gas, &e. 
but for the lighting of large apartments a smaller number of 
lamps is required than when common argands are employed. 
Naphtha—tThis article has lately been recommended as 
an economical source of light. Though naphtha gives a beau- 
tiful and steady light, yet it emits an offensive smell, and 
unless cautiously burned, is very liable to smoke; the slightest 
blast against the flame causing dense black smoke instantly to 
appear. The appearance of the shadow is so different from 
that from coal-gas, that it is not easy to fix their illuminating 
power and consequent comparative expense. In the experi- 
ments I have performed, I used the gas-argand as before, 
consuming 4 feet per hour. The naphtha-lamp had a wick 
of 4 inches in breadth, and burned with a flame of about half 
an inch in height. In one trial I made the illuminating power 
of the flames, as naphtha 1 to gas 4.233 ; in another, they were 
as 1 to 4.239 ;—-giving an average of 1 to 4.236. The con- 
sumpt of naphtha was a pint in 24 hours, at a cost of 3s. 6d. 
per gallon, that is 5id. per pint. The gas for the same time 
would be 24, or say 25 x 4 = 100—that is 10d. ; but the 
light was as 4.236 to 1—therefore the comparative expense 
comes to be as 2.2 to 1, or very nearly so. Suppose that [ 
have overrated the illuminating power of the gas as compared 
with that of the naphtha, say, that instead of 4.236, it was 
about 4, this would reduce the cost of the latter, and thus 
make the comparative expense as about 2 to 1. 
Table shewing the Consumpt and Expense of Oils, and of Gas, in Argands burning 
three feet per hour. 
| 
oe a ad 
. tive Ex- 
3 . rative Ex- 
--| Cost in farthings Compe Et pense of 
of Bshts Oils for 
> i aes equal 
Lights. 
Gas. Oil. 
Oils per Pint. 
Sperm in Argand, 1 4 
Whale do. 1 2.5 
Solar do. : 1 : 1.99 
Solar in Solar lamp, 1 1 
Naphtha lamp, 1 1 
