CHEMICAL SCIENCE. 227 



ing with this element, the heat disengaged is ample for carrying the tem- 

 perature of the mass still higher. A portion of oxide of iron being formed, 

 the mechanical motion imparted by the jets of air favors the contact of the 

 oxide with the carbon, which then burns with the condensed oxygen of the oxide 

 of iron. The products of this combustion, arising from the mingling of 

 oxide of iron and graphitic carbon and pure graphite, are two, pure iron, 

 and carbonic oxide; the former uniting with the mass, the latter escaping 

 as gas, and burning in the atmosphere, or even with any oxide of ii'on it 

 meets with in the mass. A moment's consideration of the operation shows 

 that the combustion of the iron at the first stage leads to the separation of 

 the carbon as carbonic oxide, and a reduction of the oxide formed to pure 

 iron. Silicium, phosphorus, cyanogen, and sulphur, the bases of the alka- 

 line earths, and interposed slags, are oxidized, and removed as fusible com- 

 pounds in the same way, while the pure iron assumes the crystallized state. The 

 combustion of the iron raises the temperature of the acting bodies far above 

 the initial point, while the reduction of the oxide of iron formed diminishes 

 in a corresponding degree this temperature. Were the conditions of the 

 experiment such that the oxide formed from the iron burned was equivalent 

 to converting the carbon into carbonic oxide only, at the moment the oxide 

 of iron became pure iron, then no increase of temperature would be noted, 

 and the cooling influences of the surrounding medium would cool the acting 

 bodies below the initial temperature. Hence, it is essential that more than 

 an equivalent of iron should be burned, and a loss of this substance must 

 take place, so that the operation of purification by the new process is carried 

 on by substituting iron as fuel for carbon consumed in the ordinary process. 

 Assuming six pounds of carbon to exist in a sample of crude iron containing 

 ninety-two pounds of pure iron in one hundred pounds, then twenty-eight 

 pounds of iron must be burned to oxide, and the six pounds of carbon will 

 exactly reproduce the twenty-eight pounds of iron, leaving ninety-four 

 parts of iron deprived of carbon. But the practical result differs from this 

 statement, inasmuch as a positive loss of at least ten pounds of iron occurs; 

 and in explaining the increased elevation of temperature, we neglect that 

 portion of the iron which, having been burned and again reduced, adds to 

 the mass, and keep in view the effect of the combustion of ten pounds of 

 iron lost in the operation at the high temperature attained. Accurately, 

 some addition to the temperature is made by the combustion of other bodies 

 present besides carbonic oxide, but there are also sources of expenditure ; 

 leaving as useful effect the amount of heat generated by ten pounds of iron 

 burned, from every one hundred pounds of melted iron taken. 



" I believe this combustion, going on momentarily with the reduction of 

 the oxide, is sufficient to afford the excess of heat required to maintain the 

 temperature of the mass of iron above the initial temperature for the short 

 time of thirty or forty minutes, during which the conversion takes place in a 

 nearly closed vessel. 



" The other point in this connection is the condition of the pure iron at 

 the moment of its conversion. As this is the most important to a correct 

 conception of the practical bearing of the method, it was deemed necessary 

 to describe briefly the ordinary mode of puddling iron, and reference is now 

 made to that part where it is stated, that, as tho iron becomes pure, it is less 

 fusible. 



"In ordinary, this less fusible part is 'gathered/ and forms 'puddle- 

 balls ; ' if not thus removed, and time sufficient were allowed, the whole 



