1901.] on Metals as Fuel. 497 



lieat and light they produce, just as ordinary fuels are burnt, excej)t 

 that in burning ordinary fuels combustion is often effected in two 

 distinct steps or stages, in the first of which carbonic oxide is formed, 

 and in the second carbonic acid, the products in both cases being 

 gaseous. When metals are burnt, the products of combustion are 

 solid, or condense to solids, and they therefore present a marked 

 contrast to ordinary fuels which, as has just been stated, yield on 

 combustion gaseous products. As I shall have but little to say 

 about the light which attends the combustion of metals, I may as 

 well dismiss the subject by reference to a familiar application of the 

 burning of metals for the purpose of illumination. It is easy to 

 fire electrically a portion of what is known as a " magnesium star," 

 and a " fire-ball " of magnesium attached to a parachute is beauti- 

 fully packed in this shell, for the loan of which I am indebted to the 

 authorities of the Eoyal Arsenal, Woolwich, and when the shell 

 explodes the stars burn and illuminate the enemy's position in the 

 darkness of night, so that guns may be laid to place projectiles in 

 the enemy's lines. 



Before proceeding further, I want to use the electric furnace as 

 affording a basis of comparison with the method of producing high 

 temperatures by the combustion of metals, which I shall proceed to 

 show subsequently. A current of 100 amperes at 200 volts is passed 

 by carbon poles into the furnace in which pig-iron is being melted ; 

 directly the last piece of iron has become fluid, the temperature of 

 the fused pool must be about 1300° C. The fluid mass is reflected 

 on the screen merely to give some indication as to the appearance of 

 such a mass at 1300° C, and not to afford a test of the capabilities 

 of the electric furnace. Later on I hope to show that a far higher 

 temperature can be produced by very simple means in a receptacle 

 of about the same capacity as the laboratory part of the furnace. 



Henceforth in the course of this lecture metals will be burnt for 

 the sake of the heat which is the result of their combustion. From 

 this point of view metallurgists have long used metals as fuel, often 

 without clue recognition of the fact, but case after case could be cited 

 in which conducting definite metallurgical operations is made possible 

 by burning portions of the metal or metals under treatment. Time 

 will perhaps be saved if I place in sharp contrast the use of ordinary 

 fuel and metallic fuel, even though it takes us rather far back, for I 

 do not want it to be thought that the use of metals as fuel is new, 

 although their adoption for this purpose has recently been greatly 

 stimulated. Here is a mass of very ordinary iron ore picked up on 

 a heath in Surrey, which skirts the site of what was once the ancient 

 forest of Anderida. The pre-historic dweller on the heath who used 

 the beautiful flint arrowheads, which are found near the iron ore, 

 merely burnt the wood of the forest to warm himself or to cook his 

 food. But the Britons whom Caesar found in Andreaswold smelted 

 iron with the wood of the forest trees, from which they prepared char- 

 coal, and smelting iron was actively conducted in Queen Elizabeth's 



Vol. XVI. (No. 95.) 2 l 



