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iron be red short, is by what is called the ram's head. If 
this can be done at one heat, that is, without replacing the 
bar in the fire, it is concluded that it is not red short. Cold 
short iron usually works well at all heats, and is not liable to 
crack when under the smith's operations, but when cold it 
will not bend far without snapping short with a granular 
appearance, the grain or crystals being much larger than 
in some of the best descriptions of iron, which may be 
granular, but the grains are fine and the colour silvery. 
Good common irons, and those of best quality for any but 
special purposes, when nicked on one side, and broken by 
the successive blows of a hammer, draw out and exhibit a 
fibrous texture similar to that of an ash stick when broken. 
Iron for turning purposes is mostly made from scrap, in 
order to get it as clear as possible, and at the same time free 
from the seams common in piled iron. 
The softest, and also the clearest iron for turning for 
cotton and other machinery, is made from wrought iron 
swarf (or turnings). Sometimes the swarf is worked by 
itself, but commonly a ball is made of good scrap, and 
while hot, fine swarf is thrown into the furnace, and the 
ball is rolled about so that the swarf adheres to it, and it 
is then taken to the hammer. Piston rods and other 
important parts of machinery are made from faggots of 
iron bars drawn under a use hammer, and frequently are 
twisted, in order to prevent the fibres and seams of the iron 
from running in the direction of its length, and also to make 
it more regular in its wear. 
Some few years since I read before this society a short 
paper, which is printed in its transactions, " On Molecular 
Changes in the Constitution of Wrought Iron ;" a subject 
which has since been investigated by the British Association. 
An extraordinary change is produced in iron by long con- 
tinued vibrations, or shocks, or blows of a hammer, but 
I am not aware that it has hitherto been satisfactorily 
