iron of the finest quality, possessing strength conjoined 
with an intimate degree of fusibility. 
2. Calcareous iron-stone, that which contains lime as 
its principal earthy mixture ; holding clay in the next pro- 
portion, and both these comparatively unallayed (totally 
they never are) with sand ; which, when regularly tor re* 
fled, assumes a variety of shades generally lighter in the 
colour than the former class; which sometimes, and 
sometimes not, presents internal fibres, and which adheres 
less tenaciously to the tongue ; always contains iron, which 
can be revived, richly carbonated with a comparatively 
small quantity of coaks, and with a trifling addition of 
lime. Under this class of iron-stones are found those 
which produce iron of a fusible nature, seldom connected 
with strength, but valuable for its utility in fine castings, 
which require ornament more than durability. It is also 
from this source of mixture that I would trace the red 
short quality of bar- iron. The nature imposed upon 
crude iron in the blast-furnace by the developement of its 
mixtures, most commonly accompanies it through all its 
subsequent stages of existence as a metal. 
3. Those iron-stones whose component parts are nearly 
an equalised mixture of clay, lime and sand, which torrefy 
with a slight degree of adhesion to the tongue, assuming 
a dark-red or brownish colour, void of internal fibre, al- 
ways afford, with the local proportion of fuel, iron of an in- 
termediate quality for fusibility and softness, but generally 
possessing strength in an eminent degree. Such iron is 
excellently adapted for the manufacture of great guns, mor- 
tars, and the large species of machinery. Its application 
to the purpose of bar-iron making, would also be attended 
with the most beneficial effects, possessing neither the ex- 
treme of fusibility nor of infusibility : it would greatly pre- 
vent, in the manufacturing, a tendency, which iron possess- 
ed of these extremes has, to become red or cold short. 
