Sand, with an almost equal composition, only varying in the size of grain, should be used for moulds for making clean brass castings. It should be composed of about 94 parts of silica, 5 parts of clay, and 1 part of iron oxide. The bulk of the mould may be sand from the new red sandstone formation. The face of the mould should be covered with a mixture of 8 parts of charcoal flour and 1 part of line sand, or may be dusted with peaflour and then with the charcoal mixture.