THE BANISHMENT OF NIGHT 



again secured against the encroachments of its rivals, 

 the arc and incandescent electric lights. But just at this 

 time another rival appeared in the field that not only 

 menaced the mantle lamp but the arc and incandescent 

 light as well. Curiously enough, this new rival, acetylene 

 gas, had been brought into existence commercially by 

 the electric arc itself. For although it had been known 

 as a possible illuminant for many years, the calcium 

 carbide for producing it could not be manufactured 

 economically until the advent of the electric furnace, 

 itself the outcome of Davy's arc light. 



Even as early as 1836 an English chemist had made 

 the discovery that one of the by-products of the manu- 

 facture of metallic potassium would decompose water 

 and evolve a gas containing acetylene; and this was 

 later observed independently from time to time by 

 several chemists in different countries. No importance 

 was attached to these discoveries, however, and nothing 

 was done with acetylene as an illuminant until the last 

 decade of the nineteenth century. By this time electric 

 furnaces had come into general use, and it was while 

 working with one of these furnaces in 1892 that Mr. 

 Thomas F. Wilson, in preparing metallic calcium from 

 a mixture of lime and coal, produced a peculiar mass of 

 dark-colored material, calcium carbide, which, when 

 thrown into water, evolved a gas with an extremely dis- 

 agreeable odor. When lighted, this gas burned with 

 astonishing brilliancy, and, as its cost of production 

 was extremely small, the idea of utilizing it for illu- 

 minating was at once conceived and put into practice. 



The secret of the cheap manufacture of the carbide 



