thrown upon the floor of the foundry and separated into two parts, while
the lace fell out uninjured, and the pattern was found to be reproduced
upon each face of the casting.

The question naturally arises, Why did not the iron run through the
holes and join together? The answer may be found in the fact that the
thin film of oxide of iron, or "skin," as it is popularly called, which
always forms on the surface of molten iron, was caught in these fine
meshes, and thus prevented the molten metal from joining through the
holes. I have repeated the experiment a number of times, and find that
the meshes must be quite small (not over one fiftieth of an inch),
otherwise the metal will reunite.

I think that this observation explains the cause of many obscure flaws
found in castings, sometimes causing them to break when subjected to
quite moderate strains. We frequently find little "cold shot," or
metallic globules, embedded in cast iron or steel, impairing the
strength of the metal, and it has long been asked, "What is the cause of
this defect?" The pellicles have been carefully analyzed, under the
supposition that they might be alloys of iron and nickel, or some other
refractory metal, but the analysis has failed to substantiate this
theory. Is it not probable that in the process of casting, little drops
of molten metal are sometimes splashed out of the stream, which
immediately solidify and become coated with a skin of oxide, then
falling back into the stream of rapidly cooling metal, they do not
remelt, neither do they weld or amalgamate with the mass, owing to this
protective coating, thus forming dangerous flaws in the casting?

The process of carbonizing the delicate fabrics, leaves, grasses, etc.,
is as follows: The objects are placed in a cast iron box, the bottom of