252 INORGANIC CHEMISTRY 



The employment of the oxyhydrogen blowpipe enabled Robert 

 Hare, professor in Philadelphia, to obtain, in 1802, temperatures 

 higher than those of the most powerful industrial furnaces, and to 

 carry out on a small scale several very curious experiments, such as 

 the fusion of platinum and the volatilization of silica. You know 

 how happily Deville and Debray later applied the oxyhydrogen jet 

 for studying the metallurgy of the platinum group. The question 

 of the heating of ordinary furnaces was after long discussion an- 

 swered both practically and theoretically by the work of Ebelmen 

 and the important researches of Siemens. 



Each of these advances was followed by a set of chemical discov- 

 eries consisting either in the more profound study of certain reactions 

 or in the appearance of new compounds which enriched first science, 

 and finally industry. 



But the oxyhydrogen jet does not permit the attainment of a 

 higher temperature than 1800. The melting-point of platinum, 

 as determined by M. Violle, is 1775. It would be useful to study 

 our chemical reactions above that temperature. 



When we wished to reproduce the diamond, we soon saw that our 

 study must be extended to include the various forms of carbon. So 

 generalized, the question included the interesting topic of the solu- 

 bility of carbon in melted metals. Now, as some of the metals had 

 very high melting-points, we tried experiments with the aid of the 

 oxyhydrogen blowpipe. Under these conditions, the fusion of the 

 metal, in presence of an excess of carbon, occurred in an atmosphere 

 rich in watery vapor, and therefore oxidizing. On the other hand, the 

 combustion of the coal, and the vapor of carbon, furnished a reduc- 

 ing medium. The consequence was that unless a constant tempera- 

 ture was maintained, it was impossible to get a definite equilibrium 

 between these opposite reactions. Besides, in these conditions com- 

 plete reactions could not be obtained, and the results were variable 

 from one experiment to another. 



Already different investigators, among both scientific and indus- 

 trial workers, had tried to utilize the high temperature of the electric 

 arc, discovered a century ago by Humphry Davy. But these attempts 

 could not be successful until the perfection of the dynamo-electric 

 machine. Gramme's discovery and the gradual improvement of 

 the dynamo finally placed in the hands of chemists a powerful 

 source of electric current which was easily transformed into heat. 



By a curious coincidence, our science has been able, within a few 

 years, to thrust back the known frontiers of both heat and cold. 

 After the important experiments of M. Cailletet, which served as the 

 starting-point of these new studies, and after the original investiga- 

 tions of Raoul Pictet, Olszewski and Wroblewski, Sir James Dewar 

 was able to obtain liquid hydrogen in the static condition, and by 



