Abstract. The present author investigated the improvements of physical and mechanical properties of cast iron from a practical foundry work and attained to the next conclusions:-
The properties of cast iron vary with the cupola melting conditions remarkably, consequently, if we want to produce a high quality cast iron, it is necessary to get a suitable melting condition, say, high and slow melting for the first time.
And also if we want to get a high quality cast iron, it is necessary to lowering the total carbon content of cast iron, according to the rate of cooling for the purpose of producing a cast iron with a uniform and an excellent mechanical property.
But the lowering of carbon content necessitates an addition of a resultant amount of Silicon, if we want to produce a sound casting with uniform structures. Thus it is presumed that there is a relation between the total C%+Si%, and the size of casting on the condition of a reasonable melting.
By these eonclusions, the present author produced high grade cast irons (T.C 2.5%-2.8%, Si-3.0%-2.0%, Mn 1.0%-2.0%, P, S trace) for the large and complex cast iron by the cupola direct melting Semi-Steels. But in the cupola melting, if we want to produce a low carbon Semi-Steels it is necessary to determine the cupola conditions for the restriction of carbon absorption and high temperature melting. For these Purposes, the present author already investigated the whole conditions for a cupola melting by the aid of small cupola.
Its contents are as follows:-
1 tuyere problems
2 blast volume problems
3 on the effects of carboneous matter
4 on the condition of cupola melting zone
5 on the depth of cupola hearth.
6 on the relations between the combustion gas (CO₂ CO O₂) and the change of cupola operation. etc.
After that the present author continued the same investigations on a large cupola and attained to the same conclusions, so that in this paper, he wants to make public these results, that is, the whole conditions for the mode of production of low carbon Semi-Steels by a large cupola melting.

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