the heat be carried still further a brown tinge is seen, and it is now rather soft, but greatly harder than iron, and is still elastic; saws, coach-springs, and many other articles are made from steel at this temper. If the heat be carried on to redness, the steel would be quite soft when it had slowly cooled, but if suddenly cooled (as by being plunged into water) the original hard temper comes back again. Steel, like iron, may be cast, and cast-steel is one of its most useful forms, and much resembles “fine steel.” The mode of preparing cast-steel is to melt the “blistered steel” in a crucible, or earthen pot, and then run it into a mould: this forms an “ingot” of steel, which may be afterwards rolled or welded as the case may require. Steel may be drawn into very fine wire, or wrought into the most minute articles, as the springs and other parts of watches. It bears a very fine and bright polish, and does not rust or tarnish so easily as iron. It has lately been proposed to make heavy cannon of cast-steel, which is much tougher than either cast-iron or gun-metal. Illustration: (‡ FIG. 1. and FIG. 2.) PERPENDICULAR SECTIONS OF CONVERTING VESSEL. Illustration: FIG. 3. OUTSIDE VIEW OF CONVERTING VESSEL. A process has lately been invented by Bessemer to supersede the long and laborious process of “puddling.” It consists essentially of transferring the melted iron into a vessel in which there are tubes inserted at the lower part, and through which air is forced at a great pressure, which bubbles up in streams through the melted metal, and, as it does so, unites with the carbon and sulphur of the iron, converting them into carbonic and sulphurous acids, and at the same time producing an increased heat, which is quite necessary to the success of the process, for as the iron becomes purer it also becomes more difficultly fusible, and would set into a solid mass, but that this greatly increased temperature keeps it fluid. This rising of temperature is similar to what takes place upon blowing a common fire with bellows; for the more air that is admitted to carbon raised to a very high temperature, the more rapidly does it combine with its oxygen, or, in other words, the more rapidly does it burn. So that, in this process of Bessemer’s contriving, the carbon of the iron acts as fuel to keep up the heat necessary to maintain its fusion, and at the same time, by being converted into carbonic acid, escapes in bubbles (like the bubbles which escape from soda-water), and this rapid production of gas in every part of the fused iron also assists in bringing about a thorough stirring-up and mixing together of all its parts. Reference to the accompanying diagrams will illustrate the working of the process. In figs. 1 and 2, A B are lower chambers, C is the melted iron, D is an upper chamber for melting scrap-iron, &c., E in fig. 1 and D in fig. 2 are openings for the escape of gas and flame, F F is an air-passage running all round and communicating