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pounds, cannot be sold as simple substances, it may be answered, that all the natural compounds which they contain, by being rendered dry or concentrated, could be sold as natural compounds, which may perhaps become equally valuable as others; but as long as they are mixed up with other matter, no one can say whether the valuable or valueless materials in them predominate.

(2403.) A simple list of the various ingredients at present in the market for the use of farmers will puzzle you as to the choice you should make amongst them. The names and prices are taken from the MarkLane Express of 24th April, and the New Farmers' Journal of 8th May 1843. They are as follows:

Animalized black, L.3, 3s. to L.3, 5s.

per ton at Dunbar. Agricultural salt, 34s. per ton. Chie-fou, 21s. per cwt.

Clarke's dessiccated compost, L.3:12:6
per hhd, sufficient for 3 acres.
Chloride lime, 28s. per cwt.
Daniell's new Bristol manure, 8s. per qr.
Graves, L.6, 10s. per ton.
Gypsum at the waterside, 32s. 6d. per
ton; land and housed, 38s. to 42s. per
ton according to quantity.
Grimwade's preparation for turnip-fly,
10s. 6d. per packet, sufficient for 3

acres.

Owen's animalized carbon, 25s. per ton,

free on board at Copenhagen.

Potter's artificial guano, 15s. per cwt.
Poittevin's patent disinfected manure,
13s. 6d. per qr.

Poittevin's highly concentrated manure,
30s. per qr.
Petre salt, 4s. per cwt.
Rape-dust, L.7 to L.8 per ton.
Rape-cake, L.6. 10s. to L.7 per ton.
Rags, L.4 to L.4. 10s. per ton.
Soda-ash, 14s. to 16s.
Sulphuric acid, 24d. per lb.

Sulphur for destroying worms in turnips,
16s. per cwt.

Guano, 10s. to 14s. per cwt. according to Soap-ashes, 10s per ton.

quality.

Hunt's bone-dust, 18s. per qr.

Hunt's half-inch bone, 16s. per qr.
Hunt's artificial guano, L.8 per ton.
Hunt's new fertilizer, 13s. 4d. per qr.
Lance's carbon, 12s. per qr.
Lance's humus, 14s. per qr.
Liverpool Abbatoir Company's animaliz-

ed manuring powder, L.2, 10s. per ton.
Muriate of ammonia, 24s. per cwt.
Muriate of lime, 12s. per cwt.
Nitrate of soda, 18s. to 18s. 6d. per cwt.
duty paid.

Sulphate of soda, 7s. 6d. per cwt.
Sulphate of ammonia, 18s. per cwt. at
Dundee.

Trimmer's compost for clover, wheat and

turnips.

Urate of the London Manure Company,
L.5 per ton.

Watson's granulated compost, 10s. per

cwt.

Wolverhampton imperial compost (Alex

ander's), 12s. per qr., subject to carriage to London, or forwarded from Wolverhampton.

Nitrate of potash (saltpetre) 26s. 6d. per Willey dust, L.4. 4s. per ton.

cwt.

Wright's alkalies, 28s. to 42s. per cwt.

The following are the weights per bushel of some of the substances enumerated above :

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(2404.) To reduce farm-yard dung to the saponaceous state recommended and described in (2399.), is contrary to the theory propounded by non-practical writers; and for the ordinary manuring of the farm, the recommendation, it may be acknowledged, is carried to an extreme; but for the purpose of raising a good crop of turnips, and especially of that invaluable kind the Swedish, it is beyond dispute that no manure, of whatever kind, is so congenial to their constitution as well made old muck. Until, therefore, a substitute is found for this ingredient, equal to it in efficacy, and as attainable, it will be made and applied by every farmer who is desirous of raising a good crop of Swedish turnips. recorded opinions of Sir Humphry Davy on this subject, though oft referred to caution practical men against his conclusions, nevertheless deserve examination, because of the common sense-like manner in which he states his views, and on this account these should be the more explicitly refuted; and that they will one day be refuted I have no doubt, for I am persuaded that where practice and theory disagree, theory will be found to be in the wrong. In regard to the general principle of the action of vegetable manures, he says:-" There can be no doubt that the straw of different crops, immediately ploughed into the ground, affords nourishment to plants, but there is an objection to this method of using straw, from the difficulty of burying long straw, and from its rendering the husbandry foul." You observe at once, here, that the theory of the use of clean straw as a manure, is objected to solely on the score of a difficulty of using it in that state in practice. If such an objection may be valid against the use of straw, so may it be against the use of unfermented dung. If practice is to be respected in this instance, why not in the other? But Sir Humphry proceeds to render the straw more manageable when he says-" When straw is made to ferment, it becomes a more manageable manure; but there is likewise, on the whole, a great loss of nutritive matter. More manure is perhaps supplied for a rough crop; but the land is less improved than it would be, supposing the whole of the vegetable matter could be finely divided and mixed with the soil." Here the remark suggests itself, that if straw is allowed to be fermented because of its being more manageable in that state for practice, so might dung be allowed to be more fermented for the same reason. If deference is paid to practice in one case, why not in the other? To obviate the inconvenience of burying long straw, Sir Humphry recommends it to be chopped thus:"It is usual to carry straw that can be employed for no other purpose to the dunghill to ferment and decompose; but it is worth experiment, whether it may not be more economically applied when chopped small by a proper machine, and kept dry till it is

ploughed in for the use of a crop. In this case, though it would decompose much more slowly, and produce less effect at first, yet its influence would be much more lasting." I have no doubt that chopped straw would raise potatoes on strong clay land, and when applied on summer fallow, a good crop of wheat would also be raised; but in all free soils, straw, in whatever state, whether long or chopped, would only keep the soil so open as to let in drought, retard vegetation, and it would be found lying at the bottom of the furrow in an inert state, as useless in short as fire-fanged straw. In regard to the fermentation of farm-yard dung, which is a composite manure, Sir Humphry admits the propriety of its undergoing a slight fermentation, as thus: "A slight fermentation is undoubtedly of use in a dunghill; for by means of it a disposition is brought on in the woody fibre to decay and dissolve, when it is carried to the land, or ploughed into the soil; and woody fibre is always in great excess in the refuse of the farm." So that fermentation in the dunghill is necessary to the dissolution of woody fibre, and as woody fibre is in great excess in the refuse of farms, it follows that fermentation ought to be generally allowed in dunghills, so that the question of fermentation here is only one of degree. "Too great a degree of fermentation is, however, very prejudicial to the composite manure in the dunghill; it is better that there should be no fermentation at all, before the manure is used, than that it should be carried too far. The excess of fermentation tends to the destruction and dissipation of the most useful part of the manure; and the ultimate results of this process are like those of combustion." If it is here meant to convey the idea that firefanged dung is fermentation to excess, the idea is correct, for I suppose no farmer thinks otherwise; but that the usual degree of fermentation allowed in dunghills renders the manure useless is inconsistent with experience. It is quite true, as Sir Humphry says, that " It is a common practice amongst farmers to suffer the farm-yard dung to ferment till the fibrous texture of the vegetable matter is entirely broken down, and till the manure becomes perfectly cold, and so soft as to be easily cut by the spade;" but so far from the most useful part of the manure being dissipated when the dung attains this state, experience assures us that the finest Swedish turnips cannot be raised with dung in a less elaborated state; and this conclusion is inevitable, that if the most valuable part of the manure is dissipated by the fermentation usually allowed in dunghills, that most valuable part is not required for raising the best crop of Swedish turnips, and that being the case, it is unnecessary to trouble ourselves to retain it. But what are the best parts of manure? During the violent fermentation," says Sir Humphry, which is necessary for reducing farmyard manure to the state in which it is called short muck, not only a large quantity of fluid, but likewise of gaseous matter, is lost; so much so, that the dung is reduced one-half to two-thirds in weight; and the principal elastic matter disengaged is carbonic acid with some ammonia; and both these, if retained by the moisture in the soil, are capable of becoming an useful nourishment of plants." No doubt both the fluid and gaseous products of decomposing vegetables perform important functions in the economy of nature, but if they escape while dung is preparing in the best state for use, according to invariable experience, it follows as an inevitable consequence, that these products of fermentation are not requisite, in conjunction with short muck, to raise a crop of turnips. They may be useful ingredients for other purposes, and at other times, but it is

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clear that the turnip crop can be raised to a better state without than with them. Why, therefore, attempt to retain their presence on the particular occasion ?*

(2405.) Whether a more scientific mode of forming dunghills, in consonance with practice, will ever be discovered, I cannot pretend to say; but as there seems no bounds to the discovery of science in other arts, we should not limit its powers of application to the art of husbandry. Experiments are at this moment in progress on the very subject of the formation of farm-yard dunghills, in connection with which I may mention the distinguished name of Professor Henslow, of Cambridge, who, in a series of letters addressed to the farmers of Suffolk, and which have appeared in the public prints, suggests the propriety of their performing experiments to ascertain whether the ammonia which escapes in the gaseous state as a carbonate of ammonia may not be retained in dunghills by the instrumentality of gypsum? Should the event prove successful, we may perhaps expect to hear of important improvement in the management of ordinary dunghills. Till the experiments are tried, which time alone can do, I am happy in placing before you the opinion of so distinguished a philosopher as Professor Sprengel on the value of old dung, when he says in his valuable essay on manures, which ought speedily to appear in an English dress, that "The longer the dung is left in the dunghill, the more advantageous will be the preparation of the compost, because the ammonia, disengaged from the dung and urine in it, will become chemically combined with humic acid." It will be observed that these sentiments bear a strong analogy to the subject which engages the attention of Professor Henslow. As a satisfactory conclusion to the theoretical part of this subject, I give you the following explanation of the fermentation of manure, and its effects, by Dr Madden.-[Whenever dead organic matter, either animal or vegetable, is exposed to air in a moist state, it absorbs oxygen, which, by entering into combination with its carbon, destroys its original composition, and gives rise to the production of various new compounds, which in their turn suffer decomposition by means of fresh supplies of oxygen being absorbed, and so on in a continued series until the whole mass is reduced to chemical compounds of such stability as to resist the further action of oxygen under ordinary circumstances. During this series of changes the various solid compounds are converted first into fluid and then into gaseous products; which latter, by escaping into the air, become lost. Chemists are much divided as to what precise amount of decomposition is requisite to render organic matter in a proper state to become food for plants; all agree that decomposition must have commenced, some maintain that it must be completed. My own belief, founded on extensive observation and not a few experiments, is, that all the products of decomposition, in every stage, are available as food for plants, provided they are either liquid or capable of dissolving in water. These observations will, of course, regulate us in the management of the "midden.” Whenever any moist organic matter absorbs oxygen, its chemical union with its carbon gives rise to an increase of temperature, which increase enables the surrounding portions to absorb oxygen more rapidly than they otherwise would do; these parts in their turn become heated, and thus the influence extends through the entire mass, the amount of heat being proportionable to the size of the mass, its degree of moisture, and quantity of air contained within its interstices. By careful management you can retard or accelerate the fermentation of your

* Davy's Agricultural Chemistry, p. 267-89, edition of 1839.

"midden" to almost any extent, from scarcely any change taking place, to so great a rapidity as to endanger the whole taking fire from the heat evolved. The most profitable way for dung to ferment is slowly but steadily, so that by the time it is required for use, it will readily cut with a spade like soft cheese, and exhibit a uniform rich brown colour, and emit no smoke unless the air be very frosty. During fermentation, the azote contained in the various constituents of the dunghill unites with hydrogen, and forms ammonia or hartshorn, which being very volatile, is apt to escape with the watery vapour and other gaseous products of decomposition. Various means have been of late recommended to prevent this, but none of them appear to me at all satisfactory, and I believe, have not as yet given very satisfactory results when applied to practice. The best condition for a "midden" to be in is, when it contains a sufficiency of water to cut moist, and yield a little liquid by pressure, but not enough to run from it spontaneously; this is easily effected by draining the " midden" stance, if in the court, so that all superfluous moisture runs off into the drains, which, of course, must lead to the liquid manure-tank, from which in dry weather it should be pumped up and scattered uniformly over the "midden;" in this state of moisture, scarcely a perceptible quantity of ammonia is lost, as it all remains in solution, and I believe that this plan will be found in all cases to be superior to every other hitherto devised for preserving farm-yard-dung.H. R. M.]

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(2406.) The potato crop is cultivated on what is called the fallowbreak or division of the farm, being considered in the light of a green or ameliorating crop for the soil. Following a crop of grain, whose stubble is bare in autumn, the soil is ploughed early in the season, it may receive all the advantages which a winter's sky can confer it in rendering it tender; and as potatoes effect a dry and easy soil, the piece of land intended for them may be ploughed and even partially cleaned in spring. Time for cleaning is very limited in spring, and on this account the cleanest portion of the fallow-break should be chosen for the potatoes to occupy. The stubble will either have been cast, fig. 135, in autumn, or clove down without a gore-furrow, fig. 140, according as the soil is strong or free; and having been particularly pro

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