ACETYLENE. 789 



and production of high pressures and heat accounting for the 

 various volcanic disturbances and the large natural deposits of 

 petroleum and other carbonaceous material, which occur so abun- 

 dantly in some districts. 



Pure calcium carbide has a specific gravity of 2'262 ; in a dry 

 atmosphere it is odorless, but upon exposure to moisture evolves 

 the peculiar odor of acetylene. When exposed in lumps to the 

 action of ordinary air it becomes coated with a layer of hydrate 

 of lime, which protects the interior of the mass from further oxi- 

 dation. It is not inflammable, and can be exposed to the heat of 

 the ordinary blast furnace without decomposition. It is, in fact, 

 a very stable compound, its ready decomposition under the action 

 of water being quite at variance with its other chemical proper- 

 ties. It was first prepared by Woehler, in 1862, by fusing an alloy 

 of zinc and calcium with carbon. He called it acetylene carbide. 

 It forms a dark grayish or red dense mass, which upon fracture 

 shows a crystalline metallic surface. The whole process of manu- 

 facturing acetylene, from the preparation of the lime and coke 

 onward, is very simple, and the only reason why it is new as a 

 commercial product is the difficulty of causing a combination be- 

 tween the calcium of the lime and the carbon of the coke. Noth- 

 ing short of the temperature of the electric furnace (3500 to 

 4000 C.) will bring this about, and the comparative modernness 

 of this apparatus accounts for the lateness of the calcium carbide. 

 The chemistry of the process is as follows : Quicklime (CaO) and 

 coke, or any other substance whose main content is carbon (C), 

 are mixed and fused together in the electric furnace. The cal- 

 cium (Ca) of the lime combines with part of the carbon (C) of 

 the coke to form calcium carbide (CaC 2 ) ; the oxygen (O) of the 

 quicklime combining with another portion of the carbon to form 

 carbonic oxide : 



Carbonic oxide is a gas and is driven off, leaving calcium car- 

 bide and the various impurities in the furnace. The further re- 

 action to form acetylene occurs when calcium carbide is subjected 

 to the action of water : 



The following description of the commercial manufacture of 

 calcium carbide as conducted at Spray is based on a paper by G. 

 de Chalmot, who for some time had personal supervision of the 

 works of the Wilson Aluminum Company at Spray, N. C, and 



