402 On the Origin. of the Blast Furnace. 



cast iron, or iron containing less carbon, it will hardly be con- 

 tended that it did not become so when fused in contact with 

 flux, in a crucible containing pounded charcoal. Besides, it is 

 not altogether improbable, that some particular qualities of 

 ore, finely reduced and added in sparing quantities compared 

 with the mass of the fuel (at that time the charcoal of wood), 

 were found to yield, even in the low ancient bloom ery, what is 

 now so generally known to us under tlie name of gray cast iron. 

 The cost of its production, as to fuel, time and labour, would 

 confine its use to some rare and valuable purposes : antl as we 

 know of none more useful or more generally valuable in me- 

 tallurgy than the manufacture of steel, it is probable that the 

 making of the more fusible qualities of cast iron was for the 

 exclusive purpose of fabricatuig steel ; and it is also probable, 

 that gray cast iron was discovered by endeavours to form a 

 metal as fusible as the rude and limited nature of the opera- 

 tion would permit : the fusibility of iron being always in pro- 

 portion to the quantity of carbon with which it is united. 



No circumstance with which I am acquainted, conveys so 

 lively a picture of the state of the arts, as far as regards the 

 manufacture of iron, — than that the most enlightened nation 

 in Europe, as to mining and metallurgy, should in the middle 

 of the sixteenth century possess no other process for making 

 steel, than the one described above ; a process which, when 

 performed in a manner much more perfect than that described 

 by Agricola, is yet productive of an inferior and uncertain 

 quality of steel ; and in point of expense, compared w4th the 

 present manner of making steel, utterly impracticable but for 

 the purpose of mere experiment. 



Tiie perfection of such a process (however incomplete we 

 may now consider it) may piobably have led to a discovery of 

 the manifold combinations of iron with carbon in the furnace : 

 for as dark or gray fractured cast iron contained double the 

 quantity of carbon that united itself to white iron, and four 

 times the quantity contained in the crude steel (the natural 

 product of iron ores when smelted in furnaces not more than 

 three or four feet in height, as must have been the case in the 

 blast bloomery) — so in the same proportion would it be prized, 

 and found more valuable for the manufacture of steel. 



For a great length of time, a fusion of this species of cast 

 iron might have been considered as a sacred menstruum into 

 which iron was plunged for its purification, to pass into the 

 more noble, useful, and exalted state of steel. But as the arts 

 advanced, and the genius of war revealed to her ambitious sons 

 the direful effects produced by the inflammation of gunpowder 

 ill 'Strong metallic tubes, the attention of tlie founder would 



naturally 



