The effect of lead existing in the zinc metals on their various properties were studied in Zamak alloy series.
  The results obtained are as following : Lead is a very objectionable impurity in Zamak alloys.
  In the Zamak made from the zinc metals having 0.009-0.031 per cent lead in weight, the various bad properties will appear in castings.
  Magnesium is a good element to neutralise the bad effect of lead impurity, but it is very difficult to eliminate these harmful effects of lead when the quantity of lead in zinc metals is so large as above mentioned per cent in weight.

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  The question of tuyere being suitable for cupola operation when used bad coke were reported in this paper. In this experiment, however, a small cupola as 300kg. of melting-power was used only.
  From results obtained it is clarified that a cupola having tuyeres as follows is most desirable for operation using bad coke as the amount of ash is 25% in weight :
  1) a very usual figure of the tuyere ratio is as 1 : 20, and
  2) the shape of tuyere is a rest-angle, and the tuyere area at the windbelt is greater than that at the lining, thus the cross-section of the tuyere varies throughout its length, and
  3) the more the tuyere, the better the operation is being done, but the number of tuyeres in a single row tnyere cupola is four, aud then
  4) tuyeres are inclined 15-20° so as to slope downwards to enter the cupola.

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