decarburise

A blast of air was to be forced down the pipe so as to rise up among the pieces of granular iron and partially decarburise them.

James Nasmyth: Engineer, An Autobiography. Nasmyth, James 1885

I was confined to my bed, and it was then that my mind, dwelling for hours together on the experiment about to be made, suggested that instead of trying to decarburise the granulated metal by forcing the air down the vertical pipe among the pieces of iron, the air would act much more energetically and more rapidly if I first melted the iron in the crucible, and forced the air down the pipe below the surface of the fluid metal, and thus burn out the carbon and silicum which it contained.

James Nasmyth: Engineer, An Autobiography. Nasmyth, James 1885