to study it in detail. In 1808 Mr. Slade built for Cooper, Hewitt & Co., at Trenton, the first "open-hearth" furnace constructed in America, which was put in operation in December of that year. The process made slow progress for several years, and we find that 
Fig. 56.—Vertical Cross-section of an Open-hearth Furnace. in 1874 there were but 7,000 net tons[1] of steel made in that way in the whole country; but from year to year the manufacture has increased, until in the census year ending June 30, 1880, there was reported 84,302 net tons, which we find augmented to 504,351 net tons for the census year ending June 30, 1890.[2]
Within recent years there have been several efforts to produce "direct from the ore" "blooms" or "muckbar" for use instead of "wrought scrap" in the open-hearth furnace, some of which give promise of success under favorable conditions of location, ore, and fuel. There have also been several attempts to make what has been very properly called "iron sponge"[3] for use in the "open hearth." Of the details of some of these it can be said that whatever was new was not good and all that was good was not new. However, it is not improbable that a good way of making "iron sponge" will yet be devised, and there are some encouraging experiments even now in progress. In the past twenty years variously contrived rotating furnaces have been invented to produce "blooms," in which for the severe manual labor of puddling was substituted a mechanical movement of the furnace itself. Some of these contrivances have had an ephemeral success, but none have won a place among generally approved apparatus.
The Bessemer Process.
No improvement in practical metallurgy since the time of Tubal-Cain has realized such magnificent results in increasing the quantity produced and diminishing the selling price of a metal
- ↑ Swank's Annual Statistical Report of the American Iron and Steel Association for 1889.
- ↑ Census Bulletin, No. 13, Production of Steel. Report of Special Agent Dr. William M. Sweet to Robert P. Porter, Superintendent of Census.
- ↑ This is made from a rich iron ore by depriving it of its oxygen, leaving the metallic
