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

150

UNITED STATES ASSOCIATION OF

[VOL. 8

successive casts, but the variations in the chills of any one cast
will probably be found to arise from the following causes, viz:
Difference in degree of moisture in the beds, differences in the
rate of filling the molds, differences in the length of time the chill
blocks have been in use (they became apparently burnt and lose
in conducting or chilling power by long service), difference in the
grade of metal of which the chill blocks are made, (the softer grades
having less conducting power), differences in size and thickness
of the chill-blocks. (these should be absolutely uniform). In a wellmanaged car-wheel foundry the conditions of casting are practically
invariable, or perhaps we might better say, controllable. they can be
varied at will in some respects by the founder, if the furnace man
wishes to supply the car-wheel founder with metal which can be relied on to produce certain results it is necessary that the conditions
under which he makes his tests should likewise be invariable or
controllable. This is, in the casting house, not a matter of such
easy attainment, as it would appear at first sight. Much can, however, be done by constant attention and watchfulness, and in this
way only can it be decided, how far the nature of the chill is
influenced by chemical composition, and how far by physical conditions, at present it appears that a very wide variation in the
the nature of the chill can be and is produced by allotropic action.
A collection of data showing the modes of testing, grading, etc.,
in use at various furnaces with results of experience in these
matters would probably prove very interesting.
SAMUEL D. MILLS.
QUERY NO. 5.-" What are the requirements as to physical
characteristics and chemical composition of pig-iron for the manufacture of chilled iron car wheels?"
It is, of course, impossible to lay down any strict rule in regard
to the above requirements, as the practice of wheelmakers varies
much, some finding a few irons to give good results. while others
use many and various irons. In either case an iron may at one
time with one mixture work well, and at another time with another
mixture be worthless. It cannot be said of such an iron that it
is not a good ingredient of car wheel mixtures, but merely that it
will not work well with the particular mixture with which it