iron. 
consists of carbon ; and the deficiency of metal ought ne- 
ver, with a clean bottom, to exceed 1 cwt. in 20. 
Carbonated or No.' II. iron also becomes deprived of 
a considerable portion of its carbonaceous mixture in fu- 
sion ; and when run from the air-furnace is seldom better 
than No. III. metal. The loss sustained in melting may 
be averaged at 7 1-2 per cent. 
No. III. pig-iron is, after melting in an air-furnace, 
found whitish or mottled. It is seldom susceptible of the 
same nice degree of division as the superior qualities, and 
loses in fusion a much larger proportion of metal, seldom 
under 10 per cent, and frequently 12 1-2 or 15. 
The quantity of coals requisite to melt a given quanti- 
ty of iron is various, as much depends upon the quality 
and fusibility of the metal. If the furnace goes one heat 
a day with No. I. or II. iron, the quantity of coals will 
be from 20 to 25 cwt. for a ton of iron. If two or three 
heats a day, or as many tons of iron are melted at one 
kindling, the proportion of coals will be nearly weight for 
weight of the iron melted when the coals are mixed with a 
fair proportion of small : with strong large splint coals, one 
ton of good pig-iron may be completely reduced with from 
12 to 15 cwt. including the previous heating of the fur- 
nace. 
Facts illustrative of the Shrinkage and Expansion of Cast 
Iron , By David Mushet , Esq. of the Calder 
Iron Works . 18 Ph. Mag. 
THE high temperature requisite to melt cast iron has 
prevented the chemical and philosophical world in gene- 
ral from becoming acquainted with many of its habitudes 
and peculiarities in the different stages of manufacture. 
Those engaged in foundries are frequently prevented, 
from the hurry and bustle which attends manufactories, 
