In mixing lime and sand by bulk, and not by weight, it is necessary first to ascertain the cubic feet contained in the lime, a cubic foot of which weighs 391b.; hence 5 tons x 22401b./391b. = 287 cub. ft. multiplying this by 3, it is found that 861 cub. ft. of sand will be required, the weight of which can only be obtained by experiment, pit sand being given variously as from 901b. to 1001b. per cub. ft.; river Thames sand, from 911b. to 1021b.; river sand, 1171b. to 1181b., etc. Thus, with sand at 901b. per cub. ft., 34 1/2 tons will be required; with sand at 1001b., 38 1/2 tons; with sand at 1121b., 43 tons; and with sand at 1171b., 45 tons. About 8 tons of water will be required for slaking and mixing; there will result from 45 tons to 55 tons of mortar, varying both according to the weight of the sand used and the consistency to which the mortar is mixed. The exact weight can only be ascertained by experiment.