2. RATIONAL TREATMENT OF DRAININGS.

The means which must be resorted to, in order to derive the greatest benefit from the employment of drainings, have been, in great part, incidentally mentioned in the preceding chapter, when considering the constituents of urine, and the changes which it undergoes during putrefaction. Hence it will only be necessary to refer the reader to these observations, and to add a few practical remarks upon matters of detail.

1. That the preparation of a good receptacle for the drainings must be the first step towards their careful employment, is self-evident; for if they can ooze away, evaporate, or be washed away by heavy showers, not merely some, but all of the manuring elements will be lost. The requisitions here necessary are the following:-1st. That the receptacle be water-tight. This is most certainly attained by lining the interior with hydraulic cement, or by a thorough fitting together of the planks, in the event of its being constructed of wood, and by firmly puddling a stiff layer, at least a foot in thickness, of clay or loam about the bottom and sidewalls. 2nd. That it be deep rather than shallow, in order to preserve its coolness, and to expose a small surface of its contents. 3rd. That it be closed up as much as possible from the external air, or in other words, well covered. 4th. That it allow no access to the rain.-The farmer may find more precise information upon this subject in the little work entitled Populäre Düngerlehre (Popular Lessons on Manures), by Schlipf.

2. An addition from time to time of sulphuric acid is to be greatly recommended under all circumstances, whether drainings are preserved separately, or are poured upon the manure-heap in order to keep it moist. It is difficult to estimate for a given number of animals the precise weight of sulphuric acid required for this purpose, say by the week, because the quantity of urine actually furnished to the reservoir, and likewise the condition of the urine itself, depending, as it does, upon foddering, littering, &c., must vary very greatly. As an approximative calculation, it may perhaps be held that a pound of the acid should be mixed with 30 gallons of urine. It would be extremely convenient if a

scale of measurement was prepared for every receptacle, by means of which the weekly increase of the liquid could be easily ascertained, and the addition of sulphuric acid be accordingly regulated. In lieu of sulphuric acid, gypsum, green vitriol, sulphurous coal, or the ashes of pit and brown coal, might be made use of. These materials, however, from the circumstance that they must be employed (with the exception of gypsum) in far larger quantities, are open to the objection, that great masses of solid substances would speedily collect in the reservoirs. Muriatic acid also could be used, but the cheaper and more powerful sulphuric acid is much to be preferred.

Here also the opportunity must be taken of calling attention to an important precautionary measure. Sulphuric acid is notoriously a very burning and corrosive fluid; that is, it chars and destroys most animal and vegetable substances; it has, moreover, the property of growing very hot when mixed with water. Hence very severe burns may be easily incurred, if any portion of this acid is attempted to be removed from the skin by the application of a small quantity of water. For this reason, when it comes into contact with the skin, the latter should first be wiped dry with any soft substance (as paper or rag), and then be immediately washed with a large quantity of water.

3. The application of drainings to compost heaps must be also highly recommended, since by this means they can be readily brought into a very manageable form without sustaining a loss of their fertilizing power. If in collecting these heaps of compost, all the refuse matters found upon a farm (as ought to be the case) are made use of, whatever their appellations, sweepings, rubbish, sawdust, ashes of all sorts, soot, path trimmings, peat- or coal-dust, dish-water, soap-suds, blood, &c.,and the mass is kept moist by frequently pouring on urine, very considerable quantities of the latter may be gradually brought into a dry form; inasmuch as the watery portions of the urine by degrees evaporate, and the ammoniacal combinations generated by its nitrogen are firmly held and absorbed, partly by the acids which are simultaneously formed in the humus, and partly by the earth. A part of the nitrogen at the same time causes the production of nitric acid salts, which are not volatile. By occasionally stirring up

the heap, this process is very essentially accelerated. Should a pungent odour of ammonia be remarked, some sulphuric acid diluted with water should be poured on, or some gypsum added to the heap. In this mode of using drainings, also, their previous admixture with sulphuric acid will prove very serviceable. Beyond all doubt, by the accumulation of such heaps of compost upon every farm, considerable advantages may be secured, since they furnish an extra motive and obligation for the retention and employment of many substances which are ordinarily thrown away.

4. The practice adopted in many farming establishments and districts, of suffering the manure to lie under the stock, is exceedingly beneficial, so far as the drainings are concerned, since in this case they are for the greater part absorbed and retained firmly by the straw, as will be more particularly explained in the following chapter. The same remark applies equally to their employment to preserve the moisture of yard-manure.

On the question, whether it is more advantageous to apply drainings to the soil in a fresh or in a putrid state, I do not venture to express a definite opinion, on account of the numerous conflicting statements which I have received from practical farmers with regard to their experience upon this point. Theoretically considered, it must seem most consistent to apply drainings, as also stall-manure, in a fresh condition, to fields and meadows, because then putrefaction takes place in the earth, and the products of putrefaction are retained beneath the ground; whilst by long-continued keeping in the yard, a part of the manuring elements escapes into the air, and must therefore be lost. If, however, sulphuric acid is from time to time introduced into the draining-tanks or reservoirs, the putrefaction of their contents will then occur without any such loss, and the agriculturist has then in his putrid drainings a manuring material, which, like all ready fermented, putrefied, or decayed manuring substances, is distinguished by a very rapid operation on the soil, resembling that of dissolved guano, and less readily corrosive. The most certain means of preventing the corrosive action of drainings will always be that of bringing them upon the land only when it is thoroughly sodden with moisture, or, if this cannot be waited for, by diluting them with water.

The putrefaction of fresh drainings proceeds, moreover, very rapidly, when, as is usually the case, they are placed in contact with such as are already putrid, or when the sediment at the bottom of the reservoir is from time to time stirred up.

VI. STALL-MANURE AND STRAW.

1. ALTERATION OF STALL-MANURE BY KEEPING. ORDINARY stall-manure is a varying mixture of animal excrements, urine, and straw-litter. It is strong, in proportion to the quantity of urinous liquid it has absorbed; weak, in proportion to the small amount of urine and the large quantities of straw it contains. Its greater or less facility of decomposition is also in direct proportion to its strength. Amongst these ingredients the urine has the greatest tendency to putrefaction and decay, and straw the least; manure rich in urine will, therefore, pass more rapidly into fermentation, and arrive more quickly at what is called “ripeness,” than when poor in this constituent.

Fresh manure is, however, not an article of food to plants; it becomes so only by what is termed fermentation, that is, by a previous putrefaction and decay. The changes which manure undergoes by these processes of decomposition extend chiefly to its organic or combustible constituents; inasmuch as these are transformed into a brownish-black, pulverulent mass, the well-known humus, whilst a part becomes at the same time aëriform, and escapes into the atmosphere. Coincidently with this, a quantity of water is also evaporated; and from these two volatilizations it is easily understood why fermented manure is of less weight than fresh. If the matter so escaping was exclusively water, this diminution in bulk and in weight would be advantageous and desirable; for the farmer would thereby save expense in transportation, as he would employ a drier manure, and would possess in a load which had lost half its weight by

desiccation, the same fertilizing power that is contained in two equal loads of fresh manure.

The true state of matters is, however, wholly different.

It has been already stated in one of the earlier chapters, that of the proximate constituents of plants, two leading classes are distinguished, the combustible (organic), and incombustible (inorganic); of these, the first alone are capable of fermentation and putrefaction, the latter not.

It has further been shown, that amongst organic substances a distinction is made between such as contain, and such as do not contain, nitrogen, and that the former must be regarded as more scarce and valuable, as well for foddering animals as for manuring plants. Now it is precisely these nitrogenous constituents that are always first changed; for they introduce and transfer to the other ingredients the putrefactive fermentation, by the intervention of visible and invisible animals of all kinds (infusoria, maggots, worms, &c.). If by this means their nitrogen finally enters into a volatile combination, in other words, into ammonia, then it is evident that the farmer who carelessly abandons his stall-manure to the process of putrefaction, will in the generality of cases lose considerable quantities of the manuring elements it contains, and of these elements, precisely those which have the highest value. With the ammonia other volatile combinations of sulphur and phosphorus (sulphuretted hydrogen, &c.) are simultaneously generated, and these likewise escape in an aërial form. They possess an extremely offensive odour, the same as that of rotten eggs, which is strong in propor tion to the activity of the putrefactive fermentation. Hence, from the strength of the stench emitted during the putrefaction of animal manure, a tolerably accurate conclusion may be drawn with respect to the loss of strength which may be feared. The old maxim of the peasantry, "Whatever stinks is good for manuring," is perfectly true; the more, therefore, stinking gases (containing nitrogen and sulphur) and vapours escape from a dung-heap into the air, the less of course can it continue to retain.

Those parts of plants which contain little or no nitrogen, such, for instance, as straw, wood, sugar, and starch, emit no disagreeable odour during putrefaction; this kind of change is called, by way of distinction, fermentation. Animal sub