The limoite which contains much arsenic has been roasted under several conditions. In the stream of air, it is necessary to heat above 1000°C to get good results, but if the graphite was added this temperature can be reduced to about 900°C. Addition of pyrite is effestive for the removal of arsenic, while that of pyrite cinder gives bad effect. Calcium carbonate also hinders the removal of arsenic.
In the streams of nitrogen and carbon dioxide, good results can be obtained at lower temperatures and in these cases too, graphite is effective and calcium carbonate is injurious for the removal of arsenic.

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In the present report, the relation of the charge coke ratio and the blast volume in cupola operation by low grade coke were discussed. The "Rate of Excess Air" Ew has been defined as EW=WR-WT/WT×100(%) where WR is the real blast volume used on the practical operation, and WT is the theoretical blast volume for the complete combustion of charge coke.
Data explained in the first report was used. Results obtained were summarized as follows.
(1) The temperature of molten metal is rised with increasing of charge coke ratio in constant EW and is rised with increasing of EW in the constant cbarge coke ratio.
(2) The melting velocity shows maximum at the certain point with increasing of charge coke ratio in constant EW, but increases with increasing of EW in the constant charge coke ratio.

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In the present investigation, the 2ry Tuyere were used to combust the excess CO to CO₂ and utilize the combustion heat to preheat the charge. The 2ry tuyere was attached at 1, 300mm anove the 1ry tuyere level on 3t cupola.
Results obtained were summarized as follows.
(1) The blast by the 2ry tuyere combust the excess CO gas and the charge is preheated by this combustion heat.
(2) The blast pressure at the 1ry tuyere level is lowered and the coolnig effect on the tuyere is reduced.
(3) The temperature of molten metal is rised and the melting velocity increases.

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The authors have studied on the promotion of repidity and reliability, and the simplification of the usual method The outline of precedure is as follows:-
(1) Sample is dissolved by HClO₄ (60%) sol.
(2) After phosphorus in sample is oxidized, suturated KMnO₄ sol. is added drop by drop and excess of KMnO₄ is reduced by adding of little H₂O₂.
(3) Subsequently, phosphorus is precipitated by adding of HNO₃, NH4NO₃ and (NH4)2MoO₄ sol.
(4) The following is entirely the same as the ordinary volumetric procedure.

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The authors have studied on the promotion of repidity and simplification of phosphorus in steel. As a result, time of analys's has shorten to twenty minutes The outline of procedure is as follows:-
(1) Sample is dissolved by HNO₃ (1:1) sol.
(2) phosphorus in sample is oxidized by KMnO₄ (2%) sol.
(3) Excess of KMnO₄sol. is reduced by H₂O₂ and NH₄-Cl (35%) sol.
(4) Phosphorus is precipitated by NH₄NO₃ and (NH₄)₂ MoO₄ sol.
(5) Precipitation is immediately filtered by glassfilter.
(6) The follwing is entirely the same as the ordinary volumetric procedure.

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