THE following brief paper is intended to apply to the concentration of the silver-lead ores at Broken Hill, New South Wales, generally, but more particularly to the process as applied to the ores in the Block 10 mine. The attached plans are similar in many respects to those prepared recently for the Block 10 Company. Most of the information here given is already well known to those members who are conversant with the concentration practices of this field, but it is the writer's object to give just a few of those figures -which he found difficult to obtain when first engaging in practical work. At that time no text-books were at hand from which it was possible to get sufficient details for practical working purposes.