160 On the Principles of Iron and Steel. . 
only relate to thefe principles as they become united to the 
Tren in fufion: they may alfo be prefented to crude iron int 
the. procefs of cementation; in which cafe carbon unites 
to iron in an aériform ftate, diftending the particles and 
foftening the mafs: oxygen, on the contrary, attacks the 
metal, and reduces it to a dark blue oxyd deftitute of metallic 
brilliancy and weight; but of this more hereafter. 
Steel, from its great affinity to crude iron, ought next to 
be mentioned; but as manufaéturers hitherto have placed it 
as the third exifting ftate of the metal, it will be mentioned 
in that order. 
To produce malleable iron in its pure ftate, many and 
various have been the proceffes adopted: thefe however have 
all in fome meafure fallen fhort. Malleable iron ought to 
poffefs no foreign mixture whatever, to be in a ftate of 
purity; but as the modes of operation have hitherto con- 
fitted in manufacturing this ftate of the metal’ from crude 
iron, and as otade iron is always found to contain princi- 
ples inimical to malleability, it is obvious, that the quality 
of malleable iron will at all times depend upon the degree of 
expulfion of the alterative mixtures contained in the crude 
iron; the deftruction of which, and the confequent mallea-_ 
bilization of the 1 iron, conftitute the univerfal acknowledged 
principles of bar-iron, making. 
From the. imperfe&t diffipation of oxygen and ae in 
the procefs of malleability, arife the various qualities of 
malleable iron; thefe may be arranged in the following or- 
‘der: 1., Hot hort iron; 2. Cold fhort iron; and, 3. Iron 
partaking of none.of thefe evils; and fo far it may be deno- 
‘minated pure malleable iron. ; es 
if. Hot fhort iron is pofleffed of an extreme degree of 
fulibility when in contact with a high degree of heat, and i is 
incapable of receiving the weight of a fmall hammer with- 
out, diffipating ; it is, however, poffeffed of an extreme 
degree of foftnefs and duétility when cold, and may then 
be bent or twifted in almoit any, direction... _ Yar arious ‘eafons 
have 
