786 POPULAR SCIENCE MONTHLY. 



ACETYLENE, THE NEW ILLUMINANT. 



By V. J. YOUMANS. 



THE advent of the electric light, the Siemens-Lungren regen- 

 erative burner, and the Welsbach incandescent mantle, all 

 within a comparatively short period, threw the lighting industry 

 into a very unsettled condition. There had begun, however, to 

 appear some order out of the chaos. As the special advantages of 

 the different systems were recognized, the purposes to which each 

 was best adapted were noted. The development of the industries 

 was going on very satisfactorily, when a new competitor appeared 

 in the shape of acetylene. It is now stated that Mr. Edison and 

 Nikola Tesla are independently working out still another system, 

 based on the vacuum-tube phenomena ; a subject in which Mr. D. 

 McFarlan Moore claims also to have made a great step in advance 

 by the invention of his vacuum vibrator. Vacuum-tube lighting, 

 however, is still in the laboratory, and, while surprising tales are 

 told of its great beauty and high efficiency, it is too soon to even 

 prophesy intelligently regarding it. Acetylene has, however, 

 during the last few years been much discussed, and considerable 

 data are available regarding it ; so that an inquiry into its history 

 and value as a practical illuminant is of interest. 



Acetylene (C a H a ) was first described by Edmund Davy, who 

 obtained it accidentally by the action of water on a mass of car- 

 bonized tartar and charcoal powder, with which he had attempted 

 to prepare potassium. He called the new gas hlumene. Some 

 years later it was rediscovered by Berthelot, who obtained it by 

 passing ethylene through a red-hot tube ; he noted its occurrence 

 in coal gas, and later succeeded in making it by passing a power- 

 ful electric current between two carbon poles in an atmosphere of 

 hydrogen. 



The resulting mixture of acetylene and hydrogen was passed 

 into an ammoniacal solution of cuprous chloride, and the insol- 

 uble copper compound thus obtained, which is extremely explo- 

 sive and has recently caused several serious accidents, was then 

 treated with hydrochloric acid, which liberated acetylene. 



Acetylene is a colorless gas, having a rather disagreeable odor, 

 somewhat resembling garlic and phosphorus. The peculiar odor 

 noticed when the burners of a gas stove strike back is due to the 

 formation of acetylene. Its specific gravity when compared with 

 air is 0*91 (ordinary coal gas has a specific gravity of about 0*607). 

 At 0, and under a pressure of 21'5 atmospheres (322*5 pounds per 

 square inch), it becomes a mobile, highly refractive liquid. Water 

 at 18 dissolves its own volume of the gas. When ignited at an 

 ordinary burner it gives a smoky, dull flame, and with oxygen 



