342 HISTORY OF CHEMISTRY. [LECTURE XVI. 



became possible after the discovery, in 1872, of the dynamo- 

 electrical machine, which was employed immediately thereafter 

 (in the North-German Refinery at Hamburg) to remove copper 

 from solutions. Other metals, such as zinc, magnesium, lead, 

 silver, gold, etc., were also produced electrically afterwards. 

 An operation of especial importance was the electrolytic pro- 

 duction of aluminium, a metal which Bunsen first prepared 

 by this method. 44 The technical process of Heroult 4r> is 

 different, however, from that of Bunsen, inasmuch as it is not 

 a fused double chloride of the metal that is electrolysed, but 

 aluminium oxide. 



This is the place to refer to the great scientific and prac- 

 tical results that Moissan obtained as the outcome of his 

 experiments with the electric furnace. 46 Specially worthy of 

 mention in this connection are the preparation of artificial 

 diamonds ; the production of calcium carbide (which had, 

 however, been discovered long before by Wohler 4 ") and of 

 many other carbides ; the preparation, in a state of purity, of 

 chromium and of other difficultly fusible metals, etc. The first 

 preparation of carborundum, which is also frequently attributed 

 to Moissan, is due rather to Acheson, 48 an American. Atten- 

 tion must be drawn to tne facts that in many of these experi- 

 ments electricity is only employed as a means of attaining to 

 high temperatures (3,000 to 4,000), and that the results can 

 also be obtained in other ways, since the same high tempera- 

 tures can, of recent years, be reached by means of chemical 

 reactions. An entirely new branch of thermo-industry has thus 

 arisen, by means of which great advances have already been 

 made, and are still to be expected, in metallurgy. Of an 

 earlier date is the employment of the oxy-hydrogen blowpipe 

 in the melting and working of platinum, 49 and so is the com- 

 bustion of carbon and other elements (such as silicon, sulphur, 



44 ?gg- Ann - 9 2 > 6 4 8 - 45 German Patent, December, 1887. 4(i Le 

 Four Electrique, Paris 1897 ; Comptes Rendus. 115, 1031 ; Il6, 218, 1429; 

 117, 425, 679 ; 118, 320, 501 ; etc. 47 Annalen. 124, 220. 48 Compare 

 also Schutzenberger, Comptes Rendus. 114, 1089. 49 Hare, Phil. Mag. 

 [3] 3 J > 35 6 ; further Deville and Debray, Ann. Chira. [3] 56, 385. 



