496 • TRANSACTIONS OF THE 



wrought and cast, and there are two varieties of cast iron, gray and white. 

 The gray is soft, not very brittle, and may be readily turned in a lathe. 

 The white is brittle, exceedingly hard, and when broken, presents to the 

 eye a radiated texture. There are several varieties of cast iron, all differ- 

 ing in their chemical composition, often containing silicum, manganese, 

 phosphorus, sulphur, calcium, carbon, &c. Carburets of iron may be con- 

 sidered the purest. Iron undergoes slow combustion when heated red hot 

 in the air, by combining with the oxygen. Silesian iron is very pure in 

 quality, and has been worked to so great a degree of tenuity, that the 

 leaves can be used as paper, if some Yankee could invent white ink. An 

 album has been made of iron sheets, the pages of which turn with the 

 same flexibility that those made of the finest fabric of rags do. All that 

 is now required to form books that will defy the destructive power of in- 

 sects in the tropics, is the ink. Nearly eight thousand square feet of this 

 iron paper may be made from one hundred weight of metal. It has been 

 generally allowed that hot blast iron is much better than cold blast. From 

 experiments that I have tried, I am convinced that the hot blast is by far 

 the strongest. 



The materials required for iron making are — 



1. Mines, or ores, natural or artificial. 



2. Fuel, charcoal, peat, coke or coal. 



3. Fluxes, limestone generally, occasionally saline matter. 



4. Atmospheric air, in quantity equal to eleven tons for a ton of iron. 



Iron ores are various in their natures, and are compounds of iron, oxy- 

 gen, silex, alumine, lime, magnesia, sulphur, carbon, and water. In the 

 conversion of cast iron into wrought iron, two processes are made use of, 

 1st. puddling ; 2d. boiling in a bath of fluid iron cinders. Which has been 

 practiced as long as iron has been known. The production of iron has 

 been increased ten fold since the invention of puddling-furnaces, and the 

 hot blast. 



Two thousand four hundred and eighty pounds of the best metal will 

 yield two thousand two hundred and forty pounds of puddled bars. The 

 principal cause of the loss is the presence of sulphur. If the carbon be 

 removed entirely, and nearly all the sulphur, the bar will be both a red 

 short, and cold short quality, and consequently imperfect. But if the car- 

 bon, the metalloids, and the sulphur are altogether removed, then the bar 

 will be ductile, tough, and possess a proper nature, nearly pure, but would 

 still have the red short property, as thirty-four parts of sulphur in one 

 hundred thousand parts of iron, are sufficient to produce a red short metal; 

 but if a larger quantity of sulphur be present the iron will be both red 

 short Jnd cold short. Hot blast iron generally contains more sulphur than 

 cold. Rich ores invariably yield red short iron, which is a quality of 

 purity. 



The term red short is applied to a certain arrangement of the particles 

 of the metal when passing into the liquid state. The same ore in the same 

 furnace, with the same kind of fuel, will produce red short, and cold short 



