498 Sir W. Boberts- Austen [Feb. 22, 



reign, and even survived into the last century in the district I am 

 contemplating. But in smelting iron, carbon became associated 

 with it and played a subtle part, rendering the iron precious for 

 certain purposes and useless for others. Iron had therefore to be 

 " decarburised " with a view to its conversion into steel, and in doing 

 this metallurgists for centuries truly burnt some of the iron itself, 

 using it actually as fuel. I will only add that the use of metals as 

 fuel assumed magnificent proportions in the hands of Bessemer, as 

 may be illustrated by an experiment. A few pounds of a compound 

 of iron, carbon, silicon and manganese is melted in the wind furnace, 

 which is simply used because it affords a convenient method of melting 

 the mass, which is turned into a small Bessemer converter. A stream 

 of oxygen is directed into the fluid mass. Air would do, but with so 

 small a mass the free nitrogen would cool it too rapidly. In a few 

 seconds the carbon in the fluid will be burnt away : nevertheless the 

 mass gradually becomes hotter and hotter, a shower of sparks rises, 

 and a brillant pyrotechnic display is the result. The metal- 

 loid silicon is now burning, and then brown fumes of iron and 

 manganese pass freely off; these metals are truly burning and are 

 maintaining the heat of the bath, and the presence of their fumes 

 shows that it is time to stop the operation. The temperature is 

 somewhere near 2000° C, but according to some recent investigations 

 of Professor Noel Hartley * a temperature of more than 2000° C. is 

 attained in the converter. Bessemer gave the world in 1856 cheap 

 steel ; we therefore owe to him the inestimable benefits that are the 

 results of that gift, and I ask you to bear in mind that his great 

 service to the industry of which we as a nation are so justly proud 

 rested on the possibility of using metalloids and metals as fuel. I 

 have already promised that in the course of the lecture I will show 

 some experiments in which the temperature will be a thousand 

 degrees higher than in the one you have just seen. In the Bessemer 

 process the products of combustion are both gaseous and solid, and 

 in a very ordinary case the heat engendered by the carbon of the 

 bath which evolves gases is only half that which results from the 

 combustion of the silicon, iron and manganese which yield solid 

 products. As regards the " open-hearth process " in the phase of 

 it which is known as the " pig and ore " process, oxygen is presented 

 and heat is produced under similar conditions to those we shall 

 consider subsequently in the case of the action of aluminium on 

 ferric oxide. 



The following table, which contains the relative calorific powers of 

 different metals and metalloids as compared with carbon, indicates the 

 advantage which certain metals possess over carbon for use as fuel. 

 The question at once presents itself — At what temperature will such 

 metals as can be used for fuel begin to abstract oxygen from the air ? 

 The answer is — It depends on the method by which the metals are pre- 



* Phil. Trans, vol. cxcvi. series A, p. 479, 1901. 



