&
sbils, and to fill the interstices of such as are porous. This hasbeen, with great propriety, called vegetable mould : for, thougha part has passed also through the animal process, it had firstpassed through the vegetable. The soils to which agriculturistsgive the name of Loams , are probably those in which it prevails}though they sometimes speak of hazel loams, in which, it wouldseem, this black-coloured substance did not abound.
There is a variety of vegetable mould, which has not all thegood qualities of this here described. It occurs on elevatedgrounds, probably long neglected, where the Musci, and suchlike coarse herbage, which thrive in a degree of cold and damp,unpropitious to more valuable plants, prevail. There seems to besomething in the nature of these wild plants which prevents themfrom rotting so completely as others ; and when the undecayedfragments are mixed with the soil, they tend to increase its po-rosity, or they fall into a kind of earth of a more porous contex-ture, receiving water like a sponge, and shrinking and swellingalternately with all the vicissitudes of the weather ; and, hence,disqualifying it for furnishing a proper hold to the roots of plants.But there are also other causes of this deficient construction; ofwhich more hereafter. Where the decayed Musci have accu-mulated to the thickness of a few inches, this is called a Mossysoil, which is always somewhat of this deficient construction.Larger accumulations are called Moss, which covers many acresof the surface of the country, and has, of late, been the subjectof much discussion.
The soil contains also metallic oxids, by which are understoodmetallic bodies, which being combined with that part of atmo-spheric air, sometimes known by the name of vital air, have losttheir metallic character. Of these the oxids of iron chiefly arediscoverable ; and the red and the orange are both so prevalent,that there is scarce any soil which does not contain less or moreof either the one or the other. When these oxids are found un-mixed, the country people call the red heel , and the orangeochre ; and they are distinguishable in the soil by the colour theyimpart. When the red oxid is prevalent, it seems to have some-what of a binding quality, preserving the soil in a pretty coth-pact.state, little disposed to alternate shrinking and swelling;and appears to be favourable to fertility, probably on that veryaccount ;-as all these red-coloured soils, under good husbandry,are found productive. The orange oxid has also a binding qua-lity ; but this is exercised on the subsoil, sand and gravel beingfrequently found there, bound by this oxid in solid masses ; andthese are injurious to the roots of plants which approach them.On the surface, it has an opposite effect, separating the particles°f the soil, and rendering the whole extremely loose and porous.A sterile soil, of a very porous quality, being lately analyzed,
v ol li. £