As Sir Henry continued his labors, he extended their scope from the production of refined iron to that of steel; and in order to protect himself, he took out a patent for each successive improvement. One idea after another was put to the test of experiment; one furnace after another was pulled down, and numerous mechanical appliances were designed and tried in practice. During these experiments he specified a multitude of improvements in the crucible process of making steel; but he still felt that much remained to be done. At the end of eighteen months, he says, "the idea struck me" of rendering cast iron malleable by the introduction of atmospheric air into the fluid metal. His first experiment to test this idea was made in a crucible in the laboratory. He there found that by blowing air into the molten metal in the crucible, by means of a movable blow-pipe, he could convert ten pounds or twelve pounds of crude iron into the softest malleable iron. The samples thus produced were so satisfactory in all their mechanical tests that he brought them under the notice of Colonel Eardley Wilmot, then the Superintendent of the Royal Gun Factories, who expressed himself delighted and astonished at the result, and who offered him facilities for experimenting in Woolwich Arsenal. These facilities were extended to him in the laboratory by Professor Abel, who made numberless analyses of the material as he advanced with his experiments. The testing department was also put at his disposal, for testing the tensile strength and elasticity of different samples of soft malleable iron and steel. The first piece that was rolled at Woolwich was preserved by Sir Henry as a memento. It was a small bar of metal, about a foot long and an inch wide, and was converted from a state of pig iron in a crucible of only ten pounds. That small piece of bar, after being rolled, was tried, to see how far it was capable of welding; and he was surprised to see how easily it answered the severest tests. After this he commenced experiments on a larger scale. He had proved in the laboratory that the principle of purifying pig iron by atmospheric air was possible; but he feared, from what he knew of iron metallurgy, that as he approached the condition of pure soft malleable iron, he must of necessity require a temperature that he could not hope to attain under these conditions. In order to produce larger quantities of metal in this way, one of his first ideas was to apply the air to the molten iron in crucibles; and accordingly, in October, 1855, he took out a patent embodying this idea. He proposed to erect a large circular furnace, with openings for the reception of melting-pots containing fluid iron, and pipes were made to conduct air into the centre of each pot, and to force it among the particles of metal. Having thus tested the purifying effect of cold air introduced into the melting iron in pots, he labored for three months in