.V/A' WILLIAM SIEMJ-:.\S, l-'.K.S. 221 



refractory materials in considerable quantities in an electric fur- 

 ; in its effects upon horticulture, as a promoter of the 

 chemical changes by which the plant takes its chief ingredients of 

 food from the atmosphere ; and as a means of mechanical pro- 

 pulsion, in which the dynamo-electric current; enters the list as a 

 rival of steam, to work either stationary machinery, hoists, or lifts* 

 or to propel trains along rail or tramways. 



ON THE APPLICATION OP THE DYNAMO-ELECTRIC CURRENT TO- 

 THE FUSION OF REFRACTORY MATERIALS IN CONSIDERABLE 

 QUANTITIES. 



Amongst the means at our disposal for effecting the fusion of 

 highly refractory metals, and other substances, none has been more 

 fully recognised than the oxy-hydrogen blast. The ingenious 

 modification of the same by M. H. Ste.-Claire Deville, known as 

 the Deville furnace, has been developed and applied to the 

 fusion of platinum in considerable quantities by Mr. George 

 Matthey, F.R.S. 



The regenerative gas furnace furnishes, however, another 

 means of attain ing extremely high degrees of heat, and this furnace 

 is now largely used in the arts among other purposes, for the 

 production of mild steel. By the application of the open-hearth 

 process, 10 to 15 tons of malleable iron, containing only traces of 

 carbon or other substances alloyed with it, may be seen in a per- 

 fectly fluid condition upon the open hearth of the furnace, at a 

 temperature probably not inferior to the melting point of platinum, 

 It may be here remarked that the only building material capable 

 of resisting such heats is a brick composed of 98'5 per cent, of 

 silica, and only T5 per cent, of alumina, iron, and lime, to bind 

 the silica together. 



In the Deville furnace, an extreme degree of heat is attained by 

 the union of pure oxygen with a rich gaseous fuel under the 

 influence of a blast, whereas in the Siemens furnace it is due ta 

 slow combustion of a poor gas, potentiated, so to speak, by a 

 process of accumulation through heat stores or regenerators. 



The temperature attainable in both furnaces is limited by 

 the point of complete dissociation of carbonic acid and aqueous 

 vapour, which, according to Ste.-Claire Deville and Bunseu, may 



