On the Molecular Change in the Constitution of Wrought Iron, from the Effects of Vibration and Concussion

Abstract

Mr. Solly exhibited a portion of an iron pin, which afforded an instance of the crystallization of fibrous malleable iron by the effects of vibration. The iron, of which this pin was made, was originally of the strongest and toughest kind, and entirely fibrous. It had become granular and brittle by being subjected to great vibration at a temperature very considerably below that of boiling water. He was unable to exhibit a sample of the identical billet from which this broken pin was made, because Mr. William Lucas, who took it with him to Manchester, had given it to Sir Henry De la Beche, to be placed in the Museum of Economic Geology; but he had provided himself with a small specimen of similar tough iron for the purpose of comparison. The manufacture of the pins was then explained. Puddle bars were made from the best Shropshire and Staffordshire cold blast grey pig iron, piled seven high, ball-furnaced, shingled, and rolled into a billet, which was drawn down to the size required under a small forge hammer. The pins were used to hold down the brasses over the neck at the end of the long shaft which turns the little mill, and this shaft, as it revolves nearly 300 times per minute, experiences a violent vibration. When the mill was in action, the temperature of the pins was not above 100° of Fahrenheit, and they were in no part nearer to the point of friction than six inches. The cause ...