1901.] on Metals as Fuel. 507 



armour plates in the positions where bolts and screws have to be 

 inserted through holes drilled to admit them. This is effected by 

 placing a little fluid " thermit " on the spot where the plate has to 

 be drilled, and the heat softens the hardened surface. It should also 

 be remembered that, with reference to the repairs of defective parts 

 of machinery, a suitable admixture of metallic oxides with the ferric 

 oxide, such as those of chromium, nickel or manganese, may be 

 reduced together with the iron derived from the ferric oxide. Eichly 

 carburised iron may be added to the molten mass, and in this way any 

 quality of steel may be produced. 



This latter reference to metallic oxides reminds us of the original 

 use for which the finely divided aluminium was employed, namely, as 

 a reducing agent for the rarer metals, and not for the sake of the heat 

 evolved by the reaction. This portion of the subject I dealt with at 

 the Koyal Institution six years ago, but there have been great advances 

 since. It would have been tedious to have conducted the experiments 

 before you, as the crucibles would have taken so long to cool ; but in 

 each of these crucibles which will now be broken open, I hope to find 

 a small mass of metal, which, until now, has not left the spot in which 

 it was reduced. [About a pound of nickel and a pound of cobalt 

 were then removed from the respective crucibles in which they had 

 been reduced.] 



Manganese and chromium containing only small quantities of 

 carbon are now produced on a large scale for industrial use. As 

 regards the reduction of metals and alloys from their oxides by burn- 

 ing aluminium, the following are the most recent results that have 

 been obtained. * The use of carbon-free chromium in connection with 

 the metallurgy of steel is an exceedingly useful development of the 

 methods we have considered. Hitherto, the addition of ferro-chrome 

 to steel has evolved a loss of from 20 to 25 per cent, of the chromium 

 while with pure chromium the loss is slight. Moreover, the addition 

 of ferro-chrome incidentally raises the percentage of carbon, and steel 

 containing, for instance, 2*5 per cent, of chromium should not have 

 more than from 0*15 to 0*20 per cent, of carbon, and this can only 

 be attained by the use of pure chromium. In the manufacture, also, 

 of tool steel, the percentage of chromium may reach from 6 to 10 per 

 cent, and even higher, a result which is only rendered possible by the 

 use of pure chromium. In the same way, in connection with the 

 metallurgy of copper, the possibility of providing carbon-free man- 

 ganese is important, as is also the preparation of cupro-manganese 

 free from iron. Alloys of manganese with zinc and with tin are likely 

 to prove of value. Many uses have been found for the alloy contain- 

 ing 80 per cent, of zinc and 20 per cent, of manganese, while it is 

 anticipated that the alloy containing 50 per cent, of tin and 50 per 

 cent, of manganese will also prove to be important. Use has also been 

 found for an alloy of 70 per cent, manganese and 30 per cent, chro- 



* ' Stahl imd Eisen,' March 24, 1901. 



