In the squeezer the glowing ball of white-hot iron is placed, and forced with a rotary motion through a spiral passage, the diameter of which is constantly diminishing. The effect of this operation is to squeeze all the slag and cinder out of the ball, and force the iron to assume the shape of a short thick cylinder, called "a bloom." This process was formerly performed by striking the ball of iron repeatedly with a tilt-hammer.
COLD SAW.
The bloom is now re-heated and subjected to the process of rolling. "The rolls" are heavy cylinders of cast iron placed almost in contact, and revolving rapidly by steam-power. The bloom is caught between these rollers, and passed backward and forward until it is pressed into a flat bar, averaging from four to six inches in width, and about an inch and a half thick. These bars are then cut into short lengths, piled, heated again in a furnace, and re-rolled. After going through this process they form the bar iron of commerce. From the iron reduced into this form the various parts used in the construction of iron bridges are made by being rolled into shape, the rolls through which the various parts pass having grooves of the form it is desired to give to the pieces.
HOT SAW.
