AT the works of the Biggenden Mining Company, Limited, situated in the Wide Bay District, Maryborough, Queensland, electric separation forms one of the central features of the preparation of bismuth ore produced there.The rock consisting of about equal parts of " magnetite " and " hornblende," containing about 10dwt gold per ton, and also from to 1 per cent. of bismuth, is first crushed with Huntington mills to pass .a 40-mesh screen, equal to about 225 holes per inch. The bulk of the gold is obtained from the mills and the copper aprons over which the pulp passes. From there it passes to a set of " Frue vanners," the concentrates from which consist chiefly of " magnetite" carrying 5 to 10 per cent. of bismuth. The specific .gravity of the two being about equal, it is obvious that wet concentration could go no further; and bismuth ore of such low percentage being valueless, I was induced, after making a number of exhaustive tests, and proving the principle could be successfully applied, to go in for a magnetic separator.The crude concentrates from the " Frues" are therefore dried and slowly passed through the machine, which is capable of treating 10 tons in eight hours, and the ore relieved of the whole of the " magnetite " iU thus brought up to 25 per cent. Bi, and run from the spout of the machine into canvas bags holding 1001bs , and shipped to London.