ed to a bath of
molten iron without injury, you will readily admit that they possess
some qualities not ordinarily associated with charcoal. When removed
from the mould in which they were placed after the iron casting had
cooled, not a single fiber was consumed, but _upon the face of the
casting there was found a sharp and accurate reproduction of the design,
thus forming a die_. This die may be used for a variety of purposes,
such as embossing leather, stamping paper, sheet metal, etc., or for
producing ornamental surfaces upon such castings.

Some of the carbonized fabrics displayed upon the table are almost as
delicate as cobwebs, and one would naturally suppose that when a great
body of molten metal is poured into a mould in which they are placed,
they would be torn to fragments and float to the surface even though
they were unconsumed, yet such is not the case. I have found in practice
that the most delicate fabrics may be subjected to this treatment
without danger of destruction, and that no special care is needed either
in preparing the mould or in pouring the metal.

By the aid of the megascope, the enlarged images of some of these
castings, showing the delicate tracery of the patterns, will now be
projected upon the screen, and you can all see how perfectly the design
is reproduced.

In these experiments, the mould was made in "green sand" in the ordinary
manner, and the fabric laid smoothly upon one face, being cut slightly
larger than the mould, in order that it might project over the edge, so
that when the moulding flask was closed, the fabric was held in its
proper position. As the molten metal flowed into the mould, it forced
the fabric firmly against the sand wall, and when the casting was
removed, the carbonized fabric was stripped off from its face without
injury. In this way several castings have been made from one carbonized
material.

These castings are as sharp as electrotypes, whether made of soft fluid
iron or of hard, quick-setting metal. This peculiarity is owing to the
affinity between molten iron or steel and carbon. The molten metal tends
to absorb the carbon as it flows over it, thus causing the fabric to hug
the metal closely. It is somewhat analogous to the effect of pouring
mercury over zinc. You know that when mercury is poured upon a board, it
runs in a globular form, it does not "wet" the board, so to speak; but
when poured upon a plate of clean zinc, it flows like water and wets