The investigation of the physical characters of soils has attracted little attention, and we owe all our present knowledge of the subject to a very elaborate series of researches on this subject, published by Schuebler, nearly thirty years ago. He determined _1st_, The specific gravity of the soils; _2d_, The quantity of water which they are capable of imbibing; _3d_, The rapidity with which they give off by evaporation the water they have imbibed; that is, their tendency to become dry; _4th_, The extent to which they shrink in drying; _5th_, Their hygrometric power; _6th_, The extent to which they are heated by the sun's rays; _7th_, The rapidity with which a heated soil cools down, which indicates its power of _retaining_ heat; _8th_, Their tenacity, or the resistance they offer to the passage of agricultural implements; _9th_, Their power of absorbing oxygen from the air. Each of these experiments was performed on several different soils, and on their mechanical constituents. Schuebler's experiments are undoubtedly important, and though the methods employed are some of them not altogether beyond cavil, they have apparently been performed with great care. It is nevertheless desirable that they should be repeated, for such facts ought not to rest on the authority of one experimenter, however skilful and conscientious, nor on a single series of soils, which may not give a fair representation of their general physical properties. In fact, Schuebler appears to imagine that having once determined the extent to which the sand, clay, and other mechanical constituents of the soil possess these properties, we are in a condition to predicate the effect of their mixture in variable proportions, although this is by no means probable. In examining these properties, Schuebler selected for experiment, pure siliceous sand, calcareous sand (carbonate of lime in coarse grains), finely powdered carbonate of lime, pure clay, humus, and powdered gypsum. He used also a heavy clay consisting of 11 per cent of sand and 89 of pure clay, a somewhat stiff clay containing 24 per cent of sand and 76 of clay, a light clay with 40 per cent of sand and 60 of pure clay, a garden soil consisting of 52.4 per cent of clay, 36.5 of siliceous sand, 1.8 of calcareous sand, 2 per cent of finely divided carbonate of lime, and 7.2 of humus, and two arable soils, one from Hoffwyl, and one from a valley in the Jura, the former a somewhat stiff, the latter a light soil.