336 POPULAR SCIENCE MONTHLY. 



ting calcium, but found in the furnace a brown, crystalline mass, 

 which was decomposed by pouring water on it, yielding an inflam- 

 mable gas. Willson is not a chemist, and he therefore sent specimens 

 of the material to several men of science to determine its nature. It 

 was shown to be calcium carbide, a compound of calcium and car- 

 bon, formed by the action of the carbon 011 the calcium oxide. The 

 reaction expressed in chemical symbols is CaO + 3C = CaC 2 + 

 CO. The gas formed by the action of water was acetylene, a com- 

 pound of carbon and hydrogen. The reaction is CaC 2 + H 2 O = 

 C 2 H 2 + CaO; calcium carbide and water form acetylene and lime. 

 If water enough is added, the lime is slaked, and slaked lime, or cal- 

 cium hydroxide, Ca(OH 2 ), is formed. Neither calcium carbide nor 

 acetylene was a new discovery ; acetylene was discovered by Edmund 

 Davy in 1836, and its properties were studied by Berthelot in 1862. 

 Impure calcium carbide was first made in 1862 by Wb'hler, who de- 

 scribed its decomposition by water into acetylene and lime. What was 

 there new, then, in Willson's discovery? Two important facts : (1) He 

 was the first to make carbide by a method applicable commercially; 

 (2) he was the first to make crystalline carbide. Wohler's carbide 

 was impure and amorphous; Willson's, nearly pure and crystalline, 

 so that he succeeded in obtaining United States patents for crystalline 

 carbide, and, as all carbide made by commercial processes is crystal- 

 line, its manufacture is covered by Willson's patents. 



In the same year, 1892, Prof. Henri Moissan, of Paris, an- 

 nounced the discovery of crystalline calcium carbide. Moissan's dis- 

 covery, too, was an accidental one. He was reducing refractory me- 

 tallic oxides in an electric furnace made of lime. At the close of the 

 article in which he reports his work to the French Academy of Sci- 

 ences (Comptes Rendus de V 'Academic Fran^aise, vol. cxii, page 6, 

 December 12, 1892) he refers in two lines to the formation of an ill- 

 defined carbide of calcium by the action of the carbon electrodes on 

 the lime of which his furnace was made. 



As is common with most important inventions, there is a dispute 

 as to the priority of making carbide by an electric furnace; and the 

 wonder is, not that there is a dispute, but that there are so few claim- 

 ants. A few words of explanation of the electric furnace will show 

 why. The enormous heat of the electric furnace (2000 to 3000 

 C.) is caused by an electric arc, formed by currents playing between 

 carbon electrodes ; carbon is often used in the furnace processes ; here 

 we have one constituent of calcium carbide. Lime, the material for 

 the other constituent, withstands heat better than any other common 

 substance excepting magnesia; naturally, inventors would use it, as 

 Moissan did, as a refractory lining to the furnace. Electric furnaces 

 were not new. The conditions then were such that the discoverv of 



