Sometimes there is found in marl more clay than flint, such are actually called argillaceous marls.

Other specimens contain more flint than clay, and are commonly denominated siliceous marls.

Marl was employed in Gaul and in Britain in the days of Pliny, b. 17, c. 5-8, and has from that time been regularly employed by the cultivator as one of the best of the earthy manures. It is not, however, a very common substance in all districts; for when the farmer has to bring his fertilizers from a distance, he naturally prefers, in most situations, to carry chalk or lime, to being burthened with an extra weight of clay and sand, which perhaps his land does not need; for in ninetynine cases out of the hundred, it is the chalk of the marl which is the real fertilizing portion; and as this is the case, little need be added here to what I have already said in the articles chalk and clay.

LIME.

This fertilizer is of very ancient use ; and in many districts of England, constitutes their staple earthy manure; although, after being used to excess for ages, the soil generally contains it in quantities sufficient for the supply of the vegetation growing upon it. Its addition, therefore, no longer produces good results, and the farmer then very seriously tells us, "that the land is tired of lime."

Lime is generally employed as the substitute for chalk, as limestone, which is adapted for a manure, can be obtained in many districts of England where chalk is unknown: then again, lime, by being very finely divided, and mixing more intimately with the soil, very speedily shews its good effects; the farmer has not, as is usually the case with chalk, to wait for one or two years before he procures a return for the capital expended. The carriage, too, of lime, is much less than that of chalk. I have shown, under the head chalk, that about 41 tons of lime contain as much real manure for the cultivator, as 100 tons of chalk.

By exposure to the air lime gradually absorbs moisture, and falls to powder; it does the same more speedily if water, or what is better still, for agricultural purposes, salt and water is thrown upon it. * It is then called slaked lime: by a farther

* It is better to use salt and water, because the mixture produces, by the decomposition of the common salt, two new substances:-1st, soda, another valuable fertilizer, especially for poor light sandy soils;-and 2nd, muriate of lime, which, from its deliquescent, or moistening properties, is especially valuable for the same de

exposure to the air, it gradually absorbs the carbonic acid gas which it lost in the fire, in the process of lime burning, and becomes again carbonate of lime, or chalk.

In this state it is found an essential ingredient in the ashes of almost all vegetable substances, as I have shewn under the head chalk.

Lime answers admirably mixed with earth from banks, ditches, ponds, &c., in the proportion of one bushel of lime to a load of earth; in this way it kills the weeds, seeds, and vermin, found in the earth; and if suffered to remain for some months, and occasionally turned, it is much better. If the situation is dry, and it has free access to atmospheric air, a quantity of saltpetre is occasionally formed, which materially adds to the value of the mixture.

Lime has never been employed to much extent in the south of England, because chalk is usually obtained at less expense, but in the northern counties, the consumption of it by the cultivator is very large; and he usually procures it by burning the common limestone.

There is a species of lime, denominated by the Yorkshire farmers, "Hot Lime," which has been found not so advantageous a fertilizer. This is the lime made from the magnesian limestone; which is, in fact, a mixture of chalk and carbonate of magnesia.

Carbonate of magnesia enters into the composition of plants in but small quantities; it is therefore, in very limited proportions, the food of plants. When, by being burnt, it loses its carbonic acid, it is a long period before it again acquires it from the atmosphere; its thus remaining in a caustic state for so considerable a period mixed with the soil, cannot but be prejudicial to vegetation.

The magnesian limestone of Sunderland yielded Dr. Thomson

Magnesian limestones, from whence this hot magnesian lime is made, are usually of a pale yellow or brown; they are found

scription of land, as Mr. Fincham, of Manchester, has very well shown. Some of the richest lands in Palestine, and of southern Africa, abound in soda; and owe a considerable portion of their well known fertility to its presence.

in the counties of Derby, Durham, Leicester, Somerset, Salop, and York.

In Leicestershire, the farmers use the Breedon limestone as a manure, with considerable advantage, in the proportions of 25 to 30 bushels per acre; and in still larger proportions on richer land.

The quantity of lime applied to the soil varies according to its composition; as a general rule, clays require more than sands or light loams. It is applied in quantities varying from 50 to 200 bushels per acre.

It is generally applied in the state of powder, is usually a top dressing, but if ploughed in, this cannot be done in too shallow a manner: for the lime, by its soluble and other qualities, has naturally a tendency to descend into the earth.

On heavy clay soils, lime renders them much more friable; it lessens the adhesiveness of the clay.

For newly enclosed lands, lime is a very admirable manure; in fact, much superior to the richest dung: in Essex, the newly enclosed heaths and commons are of little worth until they have been limed or chalked; by no other mode of cultivation can they be rendered permanently productive.

SAND.

Sand is a very common application to land; the advantages derived from its use differ according to the substances of which the sand is composed.

The siliceous sands are seldom employed for the sake of the silica they contain, although often used to improve the texture of the land, and, in the case of sea sand, by the gardener for his sea kale (Crambe Maritima) for the sake of its sea water.

The calcareous sands are much oftener employed than any other description; those used by the Suffolk and Norfolk farmers owe their fertilizing properties chiefly to the presence of carbonate of lime, (chalk), remains of shells, &c.

The sea sand of Devonshire and Cornwall-of which, according to Dr. Paris, 54,000 one-horse cart-loads, each containing 18 to 20 bushels, are annually used by the farmers in the neighbourhood of Padstow Harbour-contains 64 per cent of chalk.— Minutes of the Salt Committee, 1818, p. 33.

This sand has for ages constituted the main fertilizer in many of the districts of these two counties.

The farmers take it from the sea shore, under high water mark, and carry it for some miles into the country, without

paying any tolls to the lord of the land. This they are empowered to do by a grant of Richard, Duke of Cornwall; another of Henry III, and of various Acts of Parliament, from the 6th of James II, c. 18, to the 16th of Charles II, cap. 4.

This calcareous sand must necessarily constitute a very powerful manure in all soils, especially in those where chalk is naturally deficient. In other lands they owe their chief fertilizing effects either to the salt water or to their mechanical effect upon heavy soils.

The Cornish farmers consider that the small fine-grained sand is the quickest in its effects upon the land, and will last three or four crops, but the coarse grained will endure for many

years.

ASHES.

The employment of ashes as a manure, is very general in most parts of England, although many errors are usually committed in their application, and much erroneous reasoning wasted in accounting for their unsuccessful application in some districts, or their general success in others.

The ashes usually employed for horticultural and agricultural purposes in this country are, 1st, the ashes of coal; 2nd, ashes of wood; 3rd, peat ashes; 4th, the ashes from turf, as in paring and burning; 5th, the ashes of burnt clay; 6th, the ashes from soap boilers.

I will remark upon these, in the order in which I have enumerated them.

1. Coal Ashes.-The only analysis of coals that I am acquainted with is that of earth coal, by Mr. Klafroth he found it to be composed of

The combustion of the coals dissipates almost all the gaseous matters, and the charcoal; and the remainder, or ashes, therefore, will consist almost entirely of the various earthy, a small

NEW SERIES, VOL. I, NO. I.

K

portion of charcoal, and saline, matters, of which the sulphate of lime, (gypsum), and lime, constitute about a fourth.

The presence of these last named substances gives to coal ashes almost all their value as a fertilizer, for they are always most beneficially applied to those crops which contain sulphate of lime in sensible quantities, such as to lucern, sainfoin, red clover, &c. In the garden they are more often employed, for the purpose of forming walks, and to prevent the ravages of garden mice, than as a manure; or, when they are employed as an addition to the soil, it is generally in considerable quantities, on stiff clay soils, with the intention, by the mechanical operation of the cinders, of rendering the soil more friable.

As a top dressing for lucern, red clover, sainfoin, and other grasses, there is no application superior to coal ashes.

This fact was clearly proved in some comparative experiments made by Lord Albemarle, with a variety of manures, as a top dressing for sainfoin. He found coal ashes to far exceed in

value any other fertilizer.

As a manure for gardens, it is generally employed in quantities much too large; and hence, an idea has been entertained by many gardeners, that coal ashes are inimical to plants and trees. Mr. Loudon has given several experiments of this description, (Gardener's Magazine, vol. i, p. 224).

In these experiments, one gardener imbedded his potted chrysanthemums, by placing "a large handful" at the bottom of each of his pots, and then was surprised that other pots, not thus partly filled, produced better plants.

Another "horticultural friend," states the case of a Scotch gardener, who "coated over," for two successive years, his garden with coal ashes; and then our experimentalist, who was, doubtless, a persevering character, finding that, with this over dose of cinders, the " fruit trees did not thrive so well as he expected," actually took them up, and placed under them a "substratum of ashes, in order to lay them, as he said, dry and comfortable." The trees of course grew worse, and were taken up.

It is to be lamented, that such trials as these are ever brought forward; they are merely sources of erroneous conclusions, and strong proofs of the ignorance of those who have thus been wasting their master's time and property.

At p. 408, vol. ii. of the same Magazine, Mr. Loudon has given some experiments of a very different character, which we shall give in his correspondent's own words :

I sowed, on the 15th of May, 1826, three rows of Swedish turnips