Iron in Ancient India c9.s3.21

c9.s3.21

From the accounts given above it is evident that the traditional Indian method of making steel was the crucible process of making cast-steel in a fused condition by cementation, which process should in reality be regarded as an Indian discovery. The chemical action that takes places, as suggested by Heath, is that during the application of heat to the closed crucible the dry wood and green leaves would yield charcoal as well as an abundant supply of hydrocarbons. The *joint action of carbon and hydrocarbons* on the iron greatly facilitates the formation of steel as the European method of cementation by means of *charcoal alone* used to take six or seven days, and even fourteen to twenty days, while the Indian process takes only four to six hours. Though cementation has been mentioned by Agricola in his *de re metallica*, and though Reaumer in 1722 described the process of converting bar-iron into "blistered steel," it was only in 1800 that Mr. D. Mushet took out a patent for converting malleable iron into cast-steel by fusing it in a closed crucible in contact with carbon. "Now this specification," says Mr. Heath, "unquestionably comprises the principle of the Indian process which adopts the use of dry wood, which is a substance containing the coaly or carbonaceous principle." This opinion is confirmed by Dr. Percy who says, "It is curious that Mushet's process, so far as relates to the use of malleable iron in the production of cast-steel, should in principle, and I may add even in practice too, be identical with that by which the Hindoos have from ancient times prepared their wootz. I cannot discover any essential difference between the two." ¹ Dr. Percy, however, did not take into consideration the action of carburetted hydrogen gas produced by the destructive decomposition of wood in the Indian process, though as a matter of fact in the year 1825 Mr. Charles Mackintosh actually took out a patent for converting malleable iron into steel by exposing it to the action of carburetted hydrogen gas in a closed vessel, at a very high temperature, by which means the process of conversion into steel is completed in a few hours while by the old method it was the work of from fourteen to twenty days.