THE methods of ore-extraction described by Messrs Fairweather and Barton are suitable in ore where the back is more or less self-supporting over long periods. The conditions which obtain on the upper levels of the mines situated on and near the outcrop of the Broken Hill lode are such that some other methods of winning the ore must be resorted to. CHARACTERISTICS OF ORE. Broadly speaking, the lode in the upper levels of the Proprietary Mine consisted of oxidized and carbonate ore, with large bodies of argentiferous kaolin underlying a gossan outcrop, which has been removed by open cutting. These bodies rest on high-grade sulphide ore, which may be divided into two classes- 1. Ore which has been enriched by leaching of the gangue materials, and is of a soft, friable nature, crumbling between the fingers. 2. Ore which has been enriched by the deposition of secondary sulphides, and varies from friable to hard and compact. Below these secondary sulphides occur the hard sulphides, which have been mined by open stoping.