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.

+-------------------+----------+-----------+-----------+------------+
| | | | Of 100 | |
| | | | parts of | Diminution |
| | | Water | water | in bulk |
| | | absorbed | absorbed | during |
| | | by 100 | there | drying of |
| | Specific | parts | evaporate | 100 parts |
| | gravity. | per cent. | in four | moist |
| | | | hours | soil |
| | | | at 66 deg. | |
+-------------------+----------+-----------+-----------+------------+
| Siliceous sand | 2.753 | 25 | 88.4 | 0.0 |
| Calcareous sand | 2.822 | 29 | 75.9 | 0.0 |
| Light clay | 2.701 | 40 | 52.0 | 6.0 |
| Stiff clay | 2.652 | 50 | 45.7 | 8.9