336 POPULAR SCIENCE MONTHLY. 



tini;' calcium, l)ut i'uund in the furnace a l)ro\vn, crvt^talline 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 on the calcium oxide. The 

 reaction expressed in chemical symbols is CaO + 3C = CaC2 + 

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

 pound of carbon and hydrogen. The reaction is CaC2 + HoO = 

 C2II2 + 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(0Il2), 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 1802 by Wohler, who de- 

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

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

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

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

 was im])ure and amorphous; Willson's, nearly pure and crystalline, 

 so that he succeeded in obtaining United States i)atents 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 (Coinptes Rendus de V Academie Franraise, 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 liis furnace was made. 



As is coiiiiiK.n with most im])ortant inviuitions, there is a dispute 

 as to the pi'ioi'ity of making carbide by an electric furnace; and the 

 wonder is, not that there is a dispute, hut 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, foiined li\- currents playing between 

 carbon electrodes; carbon is often used in the fui-nace ])rocesses; here 

 we have one constituent of calcium carhide. hiuie, the material for 

 the other constituent, withstands heat heller ihan any other common 

 su])stance excepting magnesia: naturally, in\ciit(irs \v<Mdd use it, as 

 Moissan did, as a refractory lining to the I'nrnai-e. I'dectric furnaces 

 were not new. The conditions then were such tiiat the discovery of 



