3 degree from 0.1-1 per cent., and so on to the sixth degree. It is stated that as technical products of the fourth degree and upwards (less than 0.01 per cent. impurity), the following metals may be obtained: cadmium, copper, gold, lead, mercury, platinum, silver and zinc. Zinc, cadmium and tin (Kahlbaum) have all risen from the third to the fourth degree since 1895. Redistilled zinc was found to contain from 0.007-0.0088 per cent. total impurity, whereas a sample of electrolytic zinc costing

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... en times as much contained 1.3 per cent. of zinc sulphate, about 6 per cent. of zinc hydroxide, 0.02 per cent. of insoluble silicate, and 0.04 per cent. of metallic impurity.