proportion, or contaminating its quality by heterogeneous 
mixtures, the value and fusibility of the metal is lost ; but 
that, by a proper increase, and always in proportion to 
this increase will the fusibility and value of the iron be 
mended. From the whole, an important lesson may be 
learned of the pernicious effects of water in the furnace, 
and how absolutely necessary it is to prepare the cokes 
without using w T ater, either to damp the fires, as in the 
usual mode, or to cool the cinders obtained from the tar 
kilns, to prevent their consuming in the open air : in all 
this hurtful operation, considerable quantities of water be- 
come fixed in the cokes, which require a very great degree 
of heat to expel. 
The preparation of iron-stone has already been fully 
attended to, and the phenomena which it exhibits under 
every stage minutely described. In consequence of va- 
rious experiments we are authorised to draw the follow- 
ing conclusions : That when pure calcareous iron-stone 
is used, it admits of having the local quantity of cokes 
diminished ; that argillaceous requires a larger portion 
than the calcareous genus ; and that siliceous iron-stone 
requires a greater proportion of fuel than any variety of 
the former genera. We have also seen that fusibility, 
either connected with strength or otherwise, is derived 
from the mixture of the ores ; and that excessive brittle- 
ness, intimately connected with infusibility, is also derived 
from the same source. From a review of these facts, we 
are forcibly impressed with the importance of combining 
the prepared iron-stones with proportions of fuel suit- 
ed to their various natures, in order to produce all the va- 
rieties of crude iron with the greatest possible ceconomy. 
Contemplating farther the same subject, it is easy to be 
conceived that a want of knowledge of the component parts 
