420 BOOK IX. 



are folded together. Since this kind of bellows does not give a vigorous blast, 

 because they are drawn apart and compressed slowly, the smelter is not 

 able during a whole day to smelt much more than half a centumpondium of 

 tin. 



Very good iron ore is smelted 55 in a furnace almost like the cupellation 

 furnace. The hearth is three and a half feet high, and five feet long and 

 wide ; in the centre of it is a crucible a foot deep and one and a half feet 

 wide, but it may be deeper or shallower, wider or narrower, according to whether 

 more or less ore is to be made into iron. A certain quantity of iron ore is 

 given to the master, out of which he may smelt either much or little iron. 

 He being about to expend his skill and labour on this matter, first throws 

 charcoal into the crucible, and sprinkles over it an iron shovel-ful of crushed 

 iron ore mixed with unslaked lime. Then he repeatedly throws on charcoal 

 and sprinkles it with ore, and continues this until he has slowly built up a 

 heap ; it melts when the charcoal has been kindled and the fire violently 

 stimulated by the blast of the bellows, which are skilfully fixed in a pipe. 



55 In the following descriptions of iron-smelting, we have three processes described ; 

 the first being the direct reduction of malleable iron from ore, the second the transition stage 

 then in progress from the direct to indirect method by way of cast-iron ; and the third a 

 method of making steel by cementation. The first method is that of primitive iron-workers 

 of all times and all races, and requires little comment. A pasty mass was produced, which 

 was subsequently hammered to make it exude the slag, the hammered mass being the 

 ancient " bloom." The second process is of considerable interest, for Jit marks one of the 

 earliest descriptions of working iron in " a furnace similar to a blast furnace, but much wider 

 " and higher." This original German Sluckofen or high bloomery furnace was used for making 

 " masses " of wrought-iron under essentially the same conditions as its progenitor the forge 

 only upon a larger scale. With high temperatures, however, such a furnace would, if desired, 

 yield molten metal, and thus the step to cast-iron as a preliminary to wrought-iron became 

 very easy and natural, in fact Agricola mentions above that if the iron is left to settle in the 

 furnace it becomes hard. The making of malleable iron by subsequent treatment of the cast- 

 iron the indirect method originated in about Agricola's time, and marks the beginning of 

 one of those subtle economic currents destined to have the widest bearing upon civilization. 

 It is to us uncertain whether he really understood the double treatment or not. In the above 

 paragraph he says from ore " once or twice smelted they make iron," etc., and in De Natura 

 Fossilium (p. 339) some reference is made to pouring melted iron, all of which would appear 

 to be cast-iron. He does not, however, describe the i6th Century method of converting cast 

 into wrought iron by way of in effect roasting the pig iron to eliminate carbon by oxidation, 

 with subsequent melting into a " ball " or " mass." It must be borne in mind that puddling 

 for this purpose did not come into use until the end of the i8th Century. A great deal of 

 discussion has arisen as to where and at what time cast-iron was made systematically, but 

 without satisfactory answer ; in any event, it seems to have been in about the end of the 

 I4th Century, as cast cannon began to appeal about that time. It is our impression that 

 the whole of this discussion on iron in De Re Metallica is an abstract from Biringuccio, 

 who wrote 15 years earlier, as it is in so nearly identical terms. Those interested will find a 

 translation of Biringuccio's statement with regard to steel in Percy's Metallurgy of Iron and 

 Steel, London, 1864, p. 807. 



HISTORICAL NOTE ON IRON SMELTING. The archaeologists' division of the history 

 of racial development into the Stone, Bronze, and Iron Ages, based upon objects found in 

 tumuli, burial places, etc., would on the face of it indicate the prior discovery of copper 

 metallurgy over iron, and it is generally so maintained by those scientists. The metallurgists 

 have not hesitated to protest that while this distinction of " Ages " may serve the 

 archaeologists, and no doubt represents the sequence in which the metal objects are found, 

 yet it by no means follows that this was the order of their discovery or use, but that iron 

 by its rapidity of oxidation has simply not been preserved. The arguments which may 

 be advanced from our side are in the main these. Iron ore is of more frequent occur- 

 rence than copper ores, and the necessary reduction of copper oxides (as most surface 

 ores must have been) to fluid metal requires a temperature very much higher than does the 

 reduction of iron oxides to wrought-iron blooms, which do not necessitate fusion. The com- 

 paratively greater simplicity of iron metallurgy under primitive conditions is well exempli- 

 fied by the hill tribes of Northern Nigeria, where in village forges the negroes reduce iron 



