优点是只通过一道工序，就能把铁矿石炼成铁），也可以用鼓风炉——第一步使铁矿石熔化，然后排除和矿石化合在一起的百分之三至四的炭，使它变成铁。
metals are not generally found in the ground in a pure state. for the most part they are combined with oxygen or sulphur. such was the case with the two specimens which cyrus harding had brought back， one of magnetic iron， not carbonated， the other a pyrite， also called sulphuret of iron. it was， therefore the first， the oxide of iron， which they must reduce with coal， that is to say， get rid of the oxygen， to obtain it in a pure state. this reduction is made by subjecting the ore with coal to a high temperature， either by the rapid and easy catalan method， which has the advan
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