25 
é 
158 On the Principles he Tron and Breed. + 
~ &c. and its prefent value is reckoned from Sl. ifs. to. 6. = 
per ton.’ 
a. Carbonated crude iron, wherein carbon fully eh 
" Tainates, and where an extra privation of oxygen has taken 
place. The fraéture of ‘this iron is dark grey inclining to 
blue, prefenting large brilliant concretions of a metallic 
luftre in the centre of the pig, but dimsinifhing in point of 
fize as they approach the furface. In this quality of tron 
the upper furface, which is left to cool in contaét with the 
open air, after being run from the blaft furnace, is partially 
convex and full of pun&tures: it is then called by the work- 
men honey-combed, and its quality is often inferred from 
the fize and depth of the punéture : its tendency to oxyda- 
tion in cooling is fill lefs than that of the fecond variety of. 
crude iron. 7 his quality is ‘well known to the manufa@turer 
and founder, under the names of No. 2, good melting pig 
tron, &c. Tts prefent value is from 61. 15s. to 7. ros. per 
ton. § 
ath. Super-carbonated crude iron, or ifon faturated to ex- 
cels with carbon, and having united to it but a feanty 
portion of oxygen. The fracture of this iron prefents att 
aftonifhing group of large, regular, metallic grains, each 
prefenting a prominent edge outwards; in this ftate the 
‘faturation of ‘carbon has been fo complete, that it exifts 
united to the iron in the ftate of plumbago; luftre rich 
and ‘brilliant, inclining to dark blue; the uppet furface 
fmooth and convex, frequently covered with a beautiful 
coating of fhining plumbago, and completely free from oxyd. 
This is the No. 1, and fmooth-faced iron of the manufaca 
turers: its‘ prefent value is 81. to 81. ros. per ton. 
Thefe are the principal varieties of crudeiron. A number 
of intermediate qualities are produced, exactly dependent 
upon the quantity of mixtures, and their relative proportions 
to each other. The greater the quantity of charcoal ufed in 
{melting the ore, the more faturated with carbon and the 
more 
