94

ADVANTAGES OF GAS.

be still more disproportionate. The quality of the gas in that town is equal to 24 spermcandles, and the price is only 3s. per 1000 cubic feet; consequently, if 25 cubic feet ofordinary gas be equal in light-giving power to one pound of wax candles, 13^ feet of theLiverpool gas would have the same illuminating power, and the cost would be a fractionless than a halfpenny contrasted with 2s. 4 d., the price of a pound of wax candles.

Dr. Letheby’s Report to the City Commissioners of Sewers, dated 10th May, 1852, givesthe following comparative statement of the value of gas as an artificial light:—

“ Five cubic feet of gas give a light equal to that of twenty-three mould candles of six to thepound, each burning at the rate of 145 grains per hour; or that of eighteen common oil lamps, eachburning the best sperm oil at the rate of 133 grains per hour; or that of 2 - 5 Argand lamps, burningthe same oil each at the rate of 450 grains per hour; or to that of thirteen sperm candles of six tothe pound, each burning at the rate of 133 grains per hour; or to that of fifteen composite candlesof six to the pound, each burning at the rate of 136 grains per hour. Now if we make an inquiryinto the relative cost of these illuminating agents, we shall find that the facts thereof may be

expressed as follows :—

Gas equal to .......... 1

Sperm oil burnt in Argand ........ 8

Mould tallow candles of six to the pound . . . . . 12

Sperm oil burnt in an open lamp . . . . . . . 17

Sperm candles of six to the pound ....... 24

Composition candles of six to the pound ...... 29

M ax candles of six to the pound ....... 30

In other words, by estimating the cost of the gas at 4s. per 1000 cubic feet, the price of mouldcandles at 6 <1. per lb., the value of sperm oil at 8s. per gallon, and the price of wax, sperm, andcomposition candles at 2s. per lb., it may be said that a shilling’s-worth of gas will go as far in theproduction of light as 8s.-worth of sperm oil burnt in an Argand lamp, or 12s.-worth of ordinarymould candles, or 17s.-worth of sperm oil burnt in an open lamp, or 24s.-worth of sperm candles,or 29s.-worth of composition candles, or 30s.-worth of wax candles.”

The relative proportions which the ordinary light-giving materials bear to 1000 cubicfeet of 13-candle gas, as estimated by Mr. Lewis Thompson, are shown in the followingtabular form :*—

| 44A lbs. of sperm candles.

484 lbs. of carefully snuffed wax candles.

54 lbs. of stearic acid candles.

52-^ lbs. of best mould candles.

544 lbs. of best dip candles.

64 gallons of purified colza oil, specific gravity - 915.

5-[» 0 - sperm oil, sp. gr. '888.

different li"ht- 2 rivinsr materials mav be readilv estimated

OOO *■

from the foregoing tabular statement of relative proportions. Thus, for instance, if the costof gas be 4#. Gd. per 1000 feet, the cost of wax candles that yield an equal quantity of lightat 2 s. 4 d. per pound, would be £5. 14s.

* The Nature and Chemical Properties of Coal-Gas.

1000 feet of common gas werefound equal to the light of

The comparative values of the