抄録
The values of analysis of sulfuric acid in chromium plating baths, especially in a high concentrated bath containing fluosilicic acid, were given with the results of higher than true values. The measuring process was by centrifugal precipitation method as follows: the precipitate of barium sulfate, which had been obtained by precipitating sulfuric acid with barium chloride, was settled in a measuring tube by a centrifugal separator and the volume of deposits was measured.
It was found that these higher values of analysis were due to the deposition of precipitates of barium chromate and barium hexafluosilicate together with barium sulfate; and the values depended on the contents of chromium (VI) oxide and potassium hexafluosilicate as well as that of sulfuric acid in the plating bath. Therefore, the values of analysis of sulfuric acid by centrifugal precipitation method was apparently observed with higher results by the higher contents of deposits other than barium sulfate.
It was further found that the total volume of these mixed precipitates also depended on the chemical conditions of the bath, besides the contents of constituents; and considerably slight errors of values were observed when the bath reached a chemically stable state.
