Iron . 
221 
is subjected to motion, frequently agitated, and extremely 
divided, how does it happen, that that iron on which the 
cold-short principle is impressed, becomes more and more 
cold-short, by a continued exposure to the combination 
of oxygen with caloric, either excited by blast or the at- 
|| tenuated heat of a wind furnace ? This fact would imply 
a generation of the alterative principle- — which is indeed 
the case— but which cannot be admitted, if the cold-short 
quality is attributed to the phosphat of iron ; unless re- 
|| course is had to the supposition of a new combination of 
| this metallic salt during the operation. 
If highly oxygenated crude iron, of any manufacture, is 
exposed to the action of a current of Rame, after its small 
portion of carbon is burnt out, and after the mass has ex- 
hibited the proper signs of malleability, it will pass into 
the state of cold-short iron ; and this principle will exist in 
proportion to the length of the exposure ; or, in other 
words, in proportion to the oxygen presented to the me- 
tal, and its tendency to quit the caloric to unite with the 
iron. 
3d. Pure malleable iron derives its strength, tenacity, 
malleability, and ductility, by being totally deprived of the 
principles which constitute the cold and hot- short qualities 
of iron. This is effected in the course of rendering it 
malleable, either by the attention of the workmen, or from 
the proper quality of the crude iron used : its fracture is 
generally clear, consisting of small regular dark blue 
grains ; by much hammering the iron commonly gains 
fibre, and is then of a light blue colour, uncommonly te- 
nacious when cold. The excellence of pure malleable 
iron is also manifested by the astonishing degree of heat it 
withstands without exhibiting the least sign of fusion, or 
without losing much of its metallic parts by oxydation. 
A line of distinction ought to be drawn betwixt the iron 
produced with wood-charcoal and pit- coal. As the nre«, 
