minute crystals, free from alkaline taste ; and is 
used medicinally for the same purposes as the car- 
bonate, and for making extemporaneous effer- 
vescing draughts with tartaric and citric acids; 
but has no medicinal superiority over the carbo- 
nate, except that it is less nauseous.—The phos- 
phate is prepared from the carbonate together 
with bones and sulphuric acid ; and forms into 
large, transparent, regular, oblique, rhombic 
prisms; and has a purely saline taste similar to 
that of common salt ; and is used in medicine as 
a mild cathartic.—The acetate is prepared from 
the carbonate together with distilled vinegar ; 
and forms into solid striated oblique rhombic 
prisms; and requires to be kept in closely- 
stopped bottles; and has a sharp bitter taste ; 
|| and is used in medicine as a diuretic. 
SOD-BURNING. See Paring and Burnine. 
SOFT GRASS. See Hotcus. 
SOIL. The covering or thin uppermost stra- 
tum of the earth’s crust. It is understood by 
_ general observers as simply the ground, without 
_ any reference to either its depth or constitution 
or uses ; by geologists, as the superficial alluvial 
or diluvial deposit of the earth, to whatever 
depth it possesses homogeneity of character ; by 
botanists, as the portion of the earth’s surface 
_ which supports vegetation, in all its classes and 
_ kinds, whether naturally or with the aid of cul- 
ture ; and by farmers and gardeners, as the por- 
_ tion of the earth’s surface which is stirred by the 
_ plough or the spade or otherwise subjected to till- 
_age. Thefirst of these four senses of soil is entirely 
| popular, and does not recognise any subsoil, and 
| is totally unsuited to any useful purpose, either 
scientific or technical; the second refers solely 
_ to manner of formation and to mineral constitu- 
| ency, and recognises subsoil only in the sense of 
| a substratum of different geognostic character 
from the soil, and therefore lying at depths vary- 
ing from less than an inch to upwardsof a thousand 
feet ; the third refers to the portion of surface, 
whether thin or thick, which, in the course of 
ages, has become impregnated with organic re- 
mains by the growth and decay of successive 
races of plants, and by either natural or artificial 
processes of manuring,—and it recognises as sub- 
soil whatever lies immediately below this vege- 
| tation-supporting stratum ; and the fourth refers 
to any uniform depth of surface which is statedly 
or occasionally worked by tillage, whether only 
an inch or two by the most scratchy methods of 
barbarous husbandry, or from eighteen to thirty- 
six inches by the most elaborate methods of 
spade-trenching, plough-trenching, and subsoil- 
ploughing,—and it recognises as subsoil all the 
matter from the plane of the bottom of this 
stratum down to any depth, small or great, 
which can affect the circulation of moisture, air, 
and heat. Our work, of course, uses the word 
principally in the fourth sense,—in that of far- 
mers and gardeners ; yet it also uses it occasion- 
ally in the third sense, or that of botanists,— 
249 
especially in so far as this sense applies to culti- 
vated land, and is quite or nearly synonymous 
with mould. The soil, in the farmer’s sense, is 
sometimes of the same depth as the mould,— 
sometimes not so deep,—and sometimes deeper ; 
and it may rest on a subsoil either similar to 
itself or dissimilar, either homogeneous or hete- 
rogeneous, either workable or rocky, either deep 
or shallow ; and, with the exception of the cha- 
racters resulting from profuse organic remains, 
tillage, and high atmospheric action, the subsoil 
may be as various in constitution and condition 
as the soil. 
arid, uncultivated grounds, the soil is strictly 
coincident with the mould, and varies in depth 
from a shallowness scarcely appreciable to not 
more than a few inches; and throughout the 
great majority of good arable lands, it either has 
naturally a great depth of all the requisites of | 
fertility, or iscapable of being artificially deepened 
to any degree which the demands of cultivation 
can require. In all the latter lands, too, however 
homogeneous any portion of it originally was 
with the subsoil, it has been so changed by arti- 
ficial pulverization, by artificial supplies of or- 
ganic matter, by artificial turnings of it to the 
action of the air and weather, and by the several 
other artificial accidents of cultivation, that it 
has now a finer texture, a darker colour, a richer 
impregnation of humus and salts, and altogether 
a different appearance and character. 
The Formation of Soils—The formation of the 
shallow soils of hills and mountains and rocky 
plains has rarely received aid from man, and has 
generally consisted in the disintegration of the 
rocky surfaces immediately below them, and in 
the natural progress and deposits of spontaneous 
vegetation. “The influence of heat and mois- 
ture tends to facilitate the gradual disintegra- 
tion of even the hardest rocks; and as soon as 
the smallest portion of loose matter or earth is 
formed on their surface, traces of an obscure 
vegetation begin to manifest themselves. Li- 
chens of various kinds spring up, one genera- 
tion succeeding another, until of their decayed 
and partially decomposed fragments, a soil is 
prepared for the reception of the mosses. These 
in their turn decay, and their decomposition 
affords a certain quantity of organic matter, 
which mixes with the disintegrated portions of 
the rocks ; and in this improved soil other kinds 
of plants are capable of subsisting. Meanwhile, 
the atmosphere still exerting its influence on the 
surface of the rocks, and the roots of the plants 
penetrating into their fissures, an augmentation 
to the mass of the soil is preparing, so that by 
such slow and gradual means a soil is formed, in 
which even forest trees can fix their roots. Thus 
that which was originally a bleak and ominous 
mass of rock, became capable of supporting suc- 
cessively the various tribes of plants, and fitted 
to reward the labours of the cultivator.” 
Throughout the great majority of | 
upland pastures, of rocky wastes, and of silicious, | | 
