ELECTROCHEMISTRY 161 



vention. The name was scarcely in chemical books, and 

 the purveyors of the rarest chemicals did not have it on 

 their lists, when Mr. Thomas Wilson, trying to make some- 

 thing else in the electric furnace, made this compound from 

 ordinary lime and carbon, and started an electrochemical 

 industry which has spread all over the civilized world. I 

 am almost tempted to say that there is a, calcium carbide 

 works everywhere, but that would really be an exaggera- 

 tion, and I will not say it. The best thing about calcium 

 carbide is that it is easy to make ; the raw materials may be 

 found almost everywhere, and wherever power is cheap a 

 flourishing calcium carbide industry may be built up. The 

 curious thing about it is that its chief use is based on 

 destroying it, acting upon it by water and forming acety- 

 lene gas. How great a boon acetylene gas has been to the 

 bicyclist, automobilist, for lighting trains, isolated houses, 

 stations, and towns, needs no recital before this audience; 

 but the value of acetylene as a means of welding with the 

 blowpipe is only commencing to be appreciated. Acetylene 

 welding is a convenience which owes its existence entirely 

 to the electrochemical production of calcium carbide, and 

 the iron and steel and other metal industries are being 

 greatly helped by its use. 



Titanium carbide is not as familiar as calcium carbide. 

 It is made in a manner similar to the production of carbo- 

 rundum, using titanium oxide, (rutile) and carbon. It has 

 no uses similar to calcium carbide, nor any like silicon car- 

 bide. But electrical engineers have discovered that as arc 

 light tips or electrodes it gives the most efficient arc light 

 yet discovered, with a light efficiency running up to 3 

 candle-power per watt of electrical energy. This is prob- 

 ably 50 per cent, of the theoretically possible conversion of 

 electrical energy into light energy, and is doubly as efficient 

 as has ever before been attained. What this means for 

 street lighting everywhere is difficult to realize; perhaps 

 the best and most easily understood comparison is to say 

 that the titanium carbide arc lamp is to the ordinary arc, 

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