1918.] The N.Z. Journal of Science and Technology. 
79 
Bending ,—A 1-in.-diameter piece must stand being bent cold 90° 
over a bar 3 in. diameter without fracture. 
Dropping .—Small castings must not break when dropped from 
height of 10 ft. on to iron block. 
The absolutely necessary qualifications are that carbon must not exceed 
0-5 per cent, and tensile strength must not exceed 32 tons per square inch. 
Castings going above these limits would require careful annealing and heat 
treatment, and commercial considerations prohibit this under the con¬ 
ditions prevailing in New Zealand. Small foundries have troubles enough 
on the moulding-floor without being called on to find the technical skill 
and delicate temperature manipulation required in scientific heat treatment. 
Before considering the merits of the various processes a few words on 
two aspects of foundry-management may not be out of place. “ To-day 
the steel-foundry man who should attempt to run his shop without chemical 
analysis of his raw materials and product would be in danger of incarceration 
as a lunatic. 55 This extract from a fine American work (The Steel Foundry, 
by J. H. Hall) should be equally true in New Zealand, as chemical analysis 
is absolutely essential for successful work. But this does not mean that the 
foundryman is to place himself and shop at the mercy of a non-practical 
but highly educated chemist. The work required is largely of a routine 
character, and the actual chemical knowledge required is very small. The 
best procedure is to use the services of a bright young fitter who will also 
be available for general engineering and draughting work in the shop. If 
such a man has made use of technical - school opportunities during his 
apprenticeship and after he will very soon be able, with the aid of available 
text-books, to carry out the routine tests necessary. This leads to the 
second question. The excessive shrinkage that is found when casting steel 
gives rise to endless trouble unless patterns are carefully designed for their 
special purpose. Questions of fillets, webs, and uniform section that may 
be virtually neglected in patternmaking for iron castings become vital 
when steel is the material to be poured. The average designer in this country 
has had no experience in this direction, and the majority of patterns or 
drawings received by a jobbing foundry will require material alteration 
before being suitable for steel practice. The young engineer referred to 
above could very well attend to, or be in charge of, the chemical and physical 
testing and the designing and draughting work required. While these 
questions may appear trivial, they are likely to be overlooked or wrongly 
solved in actual workshop practice, and they discourage and dismay the 
average foundryman who is considering the installation of a steel foundry. 
We are now ready to consider what process of obtaining molten steel 
for casting is best under New Zealand conditions. The furnaces in use for 
this purpose, placed in order of magnitude of output, are (1) acid and basic 
open-hearth furnaces ; (2) acid and basic converters ; (3) crucible furnaces ; 
(4) electric furnaces. 
(1.) The open-hearth furnaces have been successfully used only in large 
sizes, from 5 to 50 tons burden, and this is out of the question for New Zea¬ 
land. The furnace best suited to our conditions is one not exceeding a 
content of 2 tons and capable of dealing quickly and economically with a pour 
of as low as \ ton. Claims have been made that a small open-hearth furnace 
of 1 ton capacity has been developed and successfully used, but these are 
not' yet substantiated. In any case, open-hearth furnaces are heated by 
gas-producers, and the sulphur content of the coal used therein should not 
exceed 0-5 per cent., a condition that is difficult to meet. If need be, other 
serious objections could be cited, but we can safely pass on to— 
(2.) Converters : These burn out the carbon from a charge of molten pig 
iron in a pear-shaped vessel by blowing air through it. They are divided into 
