Alfred Krupp devoted much attention to the production of steel of the finest quality, and was the first German manufacturer who succeeded in casting steel in large masses. In 1862 he exhibited in London an ingot of finest crucible steel weighing twenty-one tons. Its dimensions were nine feet high by forty-four inches diameter. The uniformity of quality of this mass of metal was proven by the fact that when broken across it showed no seam or flaw, even when examined with a lens. The firm can now make such homogeneous blocks of seventy-five tons weight if required. Such ingots are formed from the contents of a great number of small crucibles, each containing from fifty to one hundred pounds of the metal. The recent developments of the manufacture of steel by the open-hearth process have removed all difficulty in procuring the metal in masses large enough for all requirements, and of a tensile strength so high as thirty-three to thirty-seven tons to the square inch. Crucible steel, however, though more expensive, still holds its place as the best and most reliable that can be produced; and nothing else is ever used in the construction of a Krupp gun. By the perfected methods in use at the Essen works, such steel can be made of a tensile strength of nearly forty tons to the square inch, and of marvellous uniformity of quality. The ores used in the Krupp works for making the best steel are red hæmatite and spathic ore, with a certain proportion of ferro-manganese. The crucibles employed are formed of a mixture of plumbago and fire-clay, shaped by a mould into a cylindrical jar some eighteen inches in height, and baked in a kiln. When in use, they are filled with small bars of puddled metal, mixed with fragments of marble brought from Villmar, on the Lahn. They are then shovelled into large furnaces, whose floors are elevated three or four feet above the ground-level. In the earthen floor of the immense room containing the furnaces are two lines of pits, one set to receive the molten metal, the other intended for the red-hot crucibles when emptied of their contents. When the crucibles have undergone sufficient heating, the furnace doors are opened simultaneously at a given signal, and the attendant workmen draw out the crucibles with long tongs, and rapidly empty them into the pits prepared for the reception of the metal. The empty crucibles when cooled are examined, and if found unbroken, are used again; but if damaged, as is usually the case, are ground up, to be utilised in making new ones.