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ervision beyond the occasional recharging of the carburettor, it is manifest that the original main coming from the generator supplying any large establishment where much warming, cooking (or motor driving) might conveniently be done with the gas could be divided within the plant-house, one branch supplying all, or nearly all, the lighting burners with plain acetylene, and the other branch communicating with a carburettor, so that all, or nearly all, the warming and cooking stoves (and the motor) should be supplied with the more economical carburetted acetylene. Since any water pump or similar apparatus would be in an outhouse or basement, and the most important heating stove (the cooker) be in the kitchen, such an arrangement would be neither complicated nor involve a costly duplication of pipes.
It follows from the fact that even a trifling proportion of vapour reduces the upper limit of explosibility of mixtures of acetylene with air, that the gas may be so lightly carburetted as not appreciably to suffer in illuminating power when consumed in self-luminous jets, and yet to burn satisfactorily in incandescent burners, even if it has been generated in an apparatus which introduces some air every time the operation of recharging is performed. To carry out this idea, Caro has suggested that 5 kilos. of petroleum spirit should be added to the generator water for every 50 cubic metres of gas evolved, _i.e._, 1 lb. per 160 cubic feet, or, say, 1 gallon per 1000 cubic feet, or per 200 lb. of carbide decomposed. Caro proposed this addition in the case of central installations supplying a district where the majority of the consumers burnt the gas in self-luminous jets, but where a few preferred the incandescent system; but it is clearly equally suitable for employment in all private plants of sufficient magnitude.
A lowering of the upper limit of explosibility is also produced by the presence of the acetone which remains in acetylene when obtained from a cylinder holding the compressed gas (_cf._ < previous next >