Queries. [Volume: 8, Issue: 3, 1889, pp. 147-152]

No. 3.]

CHARCOAL IRON WORKERS.

147

Queries.
[The answers to queries which we present in this issue, relate to
chilled castings, and taken in connection with the article on " Castiron Car Wheels," will, we feel confident, prove valuable additions to the literature of the subject. In query No. 4 Mr. Samuel
D. Mills, superintendent of the Martel furnace, St Ignace, Michigan, discusses the question of allotropism influencing the formation
of chills. While in query No. 5, Mr. A. W. Whitney, chemist
of the Whitney Car-wheel Works, of Philadelphia, treats of the
characteristics of pig-iron for the manufacture of chilled cast-iron
Car-wheels. THE EDITOR.]
QUERY No. 4.-To what extent is the formation of chills in cast.
irons of the same chemical composition influenced by physical conditions?
An inquiry into the possibilitty of allotropic action influencing the crystallization of "chilling irons," would necessitate longcontinued and very close observation of the governing conditions
under which the chills were cast, but a partial answer may prove
interesting and useful as indicating the lines along which observations should be made.
We may first consider what "allotropism" is, and what instances we have of this action in other bodies
"Allotropism " may be defined as a change which can be effected
in the nature of a simple element by physical influences.
We have also "dimorphism "or " polymorphism " in compound
bodies.
As illustrations of allotropism we may take those that are most
familiar, namely, carbon, phosphorus and sulphur. Carbon presents itself to us under the forms of lamp-black, charcoal, graphite
or plumbago and diamond, the first and last of these are the purest
forms, the graphite generally containing from one to five per cent.
of iron. The lamp-black is amorphous or without definite form,
the diamond crystallizes under the octohedral or tetrahedral systems, and the graphite under the hexagonal system. Crystals,