October, 1794
Francisco had learned, during his time in Germany, that the secret to superior steel lay not in heat alone, but in control—control of carbon, and the careful removal of impurities such as phosphorus.
Guided by the theories of Johann Friedrich Gmelin of Göttingen, he had begun to move away from the erratic puddling methods favored by the British. In their place, he pursued something more deliberate, more exact.
He designed a modified Stückofen—a compact shaft furnace—yet introduced to it what he privately called a Göttingen refinement. He preheated the air blast before it entered the furnace and employed carefully selected fluxes, particularly calcium-rich limestone sourced from the northern regions, to cleanse the molten iron.
It was not, of course, the vast production of future generations—of that he had no direct knowledge. He had never seen how such abundance would one day be achieved.
Yet he understood the principles.
And that, he believed, was enough.
