light from the best one-foot burners averages thirty-two to thirty-five candles per cubic foot. With acetylene, as with every other illuminating gas, the smaller the burner and consumption, the less light per cubic foot of gas is obtained. Another important point is that while these figures represent the best practical illumination obtained from acetylene by the burners hitherto in use, the standard flat-flame burner does not give the best gaslight; with a good Welsbach burner a cubic foot of illuminating gas will give a seventeen-candle light as an average. The comparison, to be fair, should be between acetylene and the Welsbach light.
The reader will ask whether it is not possible to burn acetylene with other forms of burner, or to use it with Welsbach mantles. Successful acetylene burners of the Argand or of the regenerative type have not yet been introduced; but in Germany a new acetylene burner with Welsbach mantle promises good results. Experiments in England with an acetylene Bunsen burner and Welsbach mantle gave a light of ninety candles per cubic foot of acetylene used. It remains to be seen whether it is necessary to modify the composition of the mantles because of the intense heat of the acetylene Bunsen flame, which gives a temperature of 2100° to 2400° C. (3812° to 4397° Fahrenheit).
It would extend this article to undue length to speak of the various uses of acetylene as an enricher of other gases, but a mixture of acetylene and Pintsch oil gas now in use on all the Prussian state railways deserves mention, as it is a success, and ten thousand tons of carbide will be used this year for lighting cars by this system. Lewes's new invention of a very cheap methane water gas which is enriched by acetylene, carried to the consumer through mains, and burned in ordinary burners, is also promising.
Insurance and police regulations vary for every country. As a rule, restrictions are put on the use of liquid acetylene, and on the amount of carbide to be kept in storage. Generators must stand in separate buildings, which, in towns, must be fireproof.
The Willson patents cover the manufacture of crystalline carbide in the United States, Canada, and the South American states; and, as all carbide made by the electric furnace is crystalline, no carbide can be made independently of these patents in these countries.
In conclusion, it may be predicted that within the next few years acetylene will prove a factor in giving us an improved and cheaper light. Whether this will be an acetylene-Welsbach light or whether the acetylene will be chiefly used as an enricher of cheaper gases the future will show.
