High frequency wave titration apparatus which had a blocking oscillation circuit using UN-955 push-pull amplification was adopted. This apparatus had about 100 M.C. frequency and was shown to be suficient for the titration of CaO in basic slags with o-0.5-N ammonium-oxalate solution. The method should be classified A and B.
Method-A : The basic slag was dissolved with HCl (1:1), neutralized with NH4OH (1:1) to pH 3.2 and the solution was titrated directly in medium of 50%CH3OH with the ammonium-oxalate solution without any filtration of SiO2 etc.
Method-B : The basic slag was dissolved with HCl (1:1) and neutralized with NH4OH (1:1) to pH6.0. The solutions which had precipitates of SiO2 and Fe(OH)3 were titraed directly also by the ammonium-oxalate solution.
The analytical error by this method was about 1.0% and time required in this analysis was 10 minuets.
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