Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER II. MANUFACTURE OF STEEL. Steel is a compound of iron and carbon, sometimes formed from wrought iron by heating the wrought iron in contact with carbon, and sometimes formed from cast iron by depriving the cast iron of all impurities except a small portion of carbon. The proportions of iron and carbon vary in the different qualities of steel; but in that used ordinarily, the carbon rarely exceeds two per cent.; for some purposes it is as low as one per cent. Good ordinary tool steel contains about one and a half per cent, of carbon. Different kinds of iron produce steel of different characters, and different qualities of steel are used for different purposes. In this country the most common mode of manufacturing steel is by a process called cementation. Mr. Bessemer has, of late years, however, introduced an entirely new system of manufacturing steel. By his process steel can be manufactured of any degree of hardness direct from the cast iron, without the intermediate operation of rendering it malleable, or, in other words, without the intermediate operation of puddling, etc. The principle of the process consists in directing a blast of cold air upon molten cast iron, the cold air ignites the carbon contained in the cast iron, and causes an intense combustion, and the carbon is consumed; and by this means the cast iron is decarbonized to the state of good tool steel, or to mild welding steel, or to the state of malleable iron, according to the length of time the combustion is continued. As carbon has a strong affinity for oxygen, and cast iron containing more carbon than steel, and steel being a compound of iron and carbon, it will be seen readily that if all the impurities of the cast iron can be got rid of, and the process of combustion can be stopped when the m...