6 INTRODUCTION. 



also largely given ; in this way the value of the bibliography is increased 

 to those who have not ready access to extensive reference libraries, since 

 the same matter is referred to as given in various publications, to one or 

 another of which most chemists have access. 



Within the last five years the renewed attention of chemists has been 

 turned toward this class of compounds, and new carbides have been pro- 

 duced in rapid succession. Experiments upon the reduction of metallic 

 oxides by means of carbon in an electric furnace have resulted in the pro- 

 duction of many of the newly discovered carbides. In studying the litera- 

 ture of these compounds, the work of one man is especially noticeable. 

 More than to all other chemists together is praise due M. Henri Moissan 

 for the untiring energy with which he has investigated the carbo-metallic 

 compounds. So often has he astonished chemists with the results of his 

 electro-chemical experiments, that new discoveries by him are likely to be 

 considered as a matter of course. M. Moissan's work upon artificial 

 diamonds is one of the greatest achievements of science in imitating 

 nature's methods. 



In conducting his experiments Moissan makes use of an electric furnace 

 of very simple construction. It consists of a limestone block in the upper 

 surface of which is chiseled a rectangular cavity, which is lined with a 

 coating of magnesia and of carbon. Through opposite sides of the block 

 are inserted stout carbon electrodes, and through one of the other sides 

 is an opening through which a carbon tube is inserted. In this tube the 

 materials to be heated are placed and thus inserted into the arc. It is 

 estimated that a temperature of 4000° is obtained in this furnace. Before 

 using the furnace it is covered with another piece of limestone, on the 

 lower side of which are layers of magnesia and carbon, which fit into or 

 cover the cavity of the lower block. So poorly do these materials conduct 

 heat that the hand may be kept on the outside of the furnace for several 

 minutes after the current is started. 



The literature of the metallic carbides is as yet confined to periodicals. 

 Following the main portion of this paper is given an author's index, 

 together with the elements to the literature of whose carbides each has 

 contributed. By referring back to the page upon which such carbides are 

 discussed the full references will be found. Below are given a few refer- 

 ences having a general bearing upon the carbides. 



Moissan. " Sur un nouveau modele de four electrique a reverbere et a electrodes 



mobiles." C. R. 117, p. 679. 

 Moissan. " Cristallisation du carbon sous Taction d'un dissolvant metallique." Bull. 



Soc. Chim. (1895) [3] 13, p. 808. 

 Maisson. " Sur la formation des carbures d'hydrogene gazeux et liquides par Taction 



de Teau sur les carbures metalliques. Classification des carbures." Bull. Soc. Chim. 



(1896) [3], 16, p. 1284, or C. R. (1896) p. 1462, or Ztschr. Elektrochem. (1896) 



P- 134- 

 Moissan (concerning those carbides which are decomposed by cold water). Ann. de 

 chim. [7] 9, p. 302 ; or Chem. Centrbl. (1896) pt. 2, p. 1082. 



