To make Portland cement red, mix with it mineral red oxide of iron in the proportion of 5 to 10 per cent, by weight. The best plan will be to mix a small quantity by way of experiment, and increase or reduce the quantity as may be found desirable. For a brown colour, cover the cement after it has set with a wash made as follows. Dissolve 1 part of sulphate of iron (green copperas)in 3 parts of water this may be applied with a turks-head or a flat whitewash brush; the concrete should then be allowed to dry in the open air. If, when the work is thoroughly dry, the colour is not dark enough, give a second coat. If alum be added to the green copperas solution, the cement becomes of a pale yellow ochre tint: while if chrome alum be added to the copperas solution, the cement work will become green.