92

ADVANTAGES OF GAS.

flames of several combustible bodies that gave an amount of light equal to it, were burnedseparately in given quantities of atmospheric air, and the times were noted at which theflames were extinguished by the contamination of the air. The following were theresults :—

Colza oil was extinguished in

Olive oil ...

Russian tallow

Sperm oil ...

Stearic acid

Wax candles

Spermaceti candles .

Coal-gas (13 candles)

Cannel gas (28 candles)

71 minutes.

72 „

75 „

76 „

77 „

79 „

83 „

98 „

1 o2 ,,

The preceding numbers may be taken to indicate the comparative salubrity of the severalilluminating materials, from which it appears that the atmosphere of a confined room lightedby cannel gas would support life twice as long as the atmosphere of the same room lightedequally by tallow candles.

Xor does the complaint that is frequently made of the heat of rooms lighted by gas,afford a much better foundation for an objection to gas-lighting than its assumed insalubrity.The fact may be true that a room lighted by gas is hotter than when lighted by candles,but the cause is to be attributed not to the greater heat-giving power of the gas, but to thegreater illumination when gas is employed. If persons would be satisfied with the samedim light to which they are accustomed when burning candles, or if they would increasethe number of the latter so as to equal the light of the gas flame, the heat given out wouldbe found to be less when burning gas than when burning lamps or candles. It has, indeed,been proved by experiment that the combustion of colza oil produces nearly twice as muchheat as the flame of cannel gas of the same standard of luminosity, and that in comparisonwith ordinary 13-sperm-candle gas the proportionate amounts of heat are as 78 to 68. Aroom lighted by a large moderator lamp burning colza oil is perceptibly heated quite asmuch as by a gas flame that gives a larger amount of light.

Having shown that the objections raised to the introduction of gas into dwellings haveno substantial foundation, it will not be difficult to prove that important advantages aregained by its adoption. The economy of gas-lighting is generally admitted, and the extentof the saving it effects has been clearly set forth by Mr. Rutter, in a small pamphlet, entitled‘ Gas in Dwelling-houses,’ published by Messrs. Parker and Son, from which the followingis an extract:—

“ The only correct method of estimating the relative cost of gas-ligh't, and of tlmt obtained fromtallow, wax, and oil, is by instituting the comparisons with equal quantities of light; each of thelight-giving materials being used under the most favourable circumstances, and strictly in accordancewith the plans pursued in actual practice. When gas is first introduced, it rarely happens that per-sons are satisfied with the same quantity of light as they had previously possessed. J3o long howeveras this extra supply is kept within moderate limits, it will cause no material difference in the resultsof the following calculations, since, with ordinary care, there need be no waste in the use of gas,