The night-soil produced upon country farms is most judiciously added to compost heaps, as it then soon loses its disgusting odour, and is converted into a pulverulent mass, which, when mixed with earth, can be easily scattered, and at the same time equably distributed over the ground. The dried human excrements here and there met with in commerce, under the name of poudrette, are of such extremely diversified composition, that the farmer ought never to make use of them without previous chemical examination.

V. DRAININGS.

A FARMER who does not carefully collect and preserve the urine of his house and live stock, acts like a miner who throws away dull, rich silver ore, because it does not shine like white silver.

are abundantly available, that the product of sewers is most wanted, or would be most appreciated. The market-gardens in the neighbourhood of London and other large towns will always have the command of abundance of manure, which is obtained at a very low cost and with little or no expense of carriage, being brought by the market-carts on their return journey. The market for sewage manure ought to be found in a wider zone. I feel persuaded that cheap manures-that is to say, manures of small value, at an equally small price-are a mistake, and every step that we take now is in the opposite direction, namely in the concentration of fertilizing qualities.

"It may be asked, is there then no plan by which a solid manure of sufficient value can be prepared from sewage? My own conviction is that as yet, no plan has been suggested which, with a due regard to the farmer's interests, unites the prospect of a paying speculation. Of course I speak now of a manufacture in which sewage is the staple raw article. *** I do not doubt that if the liquid sewage could be properly distributed over the extent of surface which it is capable of fertilizing, a revenue would be forthcoming towards the reduction of the town-rates. But in the absence of arrangements for liquid distribution, and unless we should discover some process far better than any we possess, for the solidification of the sewage, I am convinced that the results must be all the other way; that is to say, the towns must be content to pay towards the operation instead of looking to it as a source of income."

A farmer who buys guano, bone-dust, or other artificial manures, but does not look carefully after his drainings, is an extravagant farmer; for he brings the same thing into his yard at great cost, which he might have for nothing, if he did not suffer it to flow or evaporate uselessly away from the same.

That drainings fertilize the soil, every farmer must be aware, even from childhood. But how great is their power in this respect, and how much of this power may be lost by careless preservation and treatment, many farmers do not yet know. Were it otherwise, draining-tanks commodiously placed would be provided, first and foremost, in every farmyard; were it otherwise, one would find no longer on a farin great puddles of dungy and urinous drainings, which sun, moon and stars can undisturbedly shine upon, and heavy showers fill even to an overflow; were it otherwise, there would no longer be villages in which a brown current of liquid guano streams forth from every farm enclosure, to be lost in the gutters or the village pond.

If this disregard of drainings originates in a mistaken estimate of their worth, and perhaps in part from the circumstance that their fluid form renders their preservation more difficult and their employment more inconvenient than solid manure, it may be expected that information respecting the constituents of this important portion of manure, as also upon its proper treatment and use, will assist materially in removing the indifference with which it has hitherto been regarded. For this reason, in my chemical lectures before agricultural societies, it has generally formed the startingpoint from which I have proceeded to the consideration of other kinds of manure, as I am firmly persuaded that it must also form the starting-point in all improved agricultural establishments; for nothing can more nearly concern the farmer than the turning to most profitable account those fertilizing substances which are first and under all circumstances ready to his hand. It has afforded me peculiar satisfaction to learn, that the counsels I have given on the occasions referred to, have been subjected to trial and received confirmation. On this subject, therefore, instead of appealing to mere theoretical conjectures, I am able to cite facts which have stood the test of actual proof.

That a pound weight of urine is, generally speaking, of

higher value, as a means of manure, than the same quantity of solid excrement, follows very plainly from what has been said in the preceding chapter respecting its composition. Drainings acquire their great manuring value principally through the large amount of nitrogen and potash they contain. If the drainings which a cow furnishes in a twelvemonth were collected and dried, abut 6 cwt. of solid extract might be obtained from them, which in fertilizing power must be estimated as equal to Peruvian guano, now bought by the farmer in Saxony at from 13s. to 14s. per cwt. this extract there is contained as much nitrogen alone as in 5 cwt. of the best guano, and so large a quantity of potash, that by combustion more than 11⁄2 cwt. of potash, worth in commerce £3, may be readily procured.

In

With these statements, the agricultural experience of those countries where the true value of drainings as a manure has been longest known, and where they have accordingly been collected and employed with the greatest care, coincides most perfectly. Thus in Flemish agriculture the yearly urine of a cow is estimated at £2 2s., and this sum is actually paid for it there. And a celebrated English farmer relates, that, in manuring meadow-land, he has obtained a far greater effect from 160 cwt. of sewer-water from the city of Edinburgh (consisting for the most part of urine), than from 300 cwt. of stable-manure, and from 3 cwt. of guano, with which he manured three equal parcels of land, each an English acre in extent*.

1. ALTERATION OF URINE BY CONTINUED KEEPING.

It is known that urine by keeping, and very quickly at warm seasons of the year, acquires a disagreeable, pungent odour, with an alkaline quality, and that this putrid urine can be used in the same way as soap, for washing and cleansing wool from fatty and pespiratory substances, as is done, for example, in the manufacture of cloth and in wool-spinning. The volatile and alkaline body is generated in the putrefaction of the urine from its nitrogenous constituents

* The influence of large quantities of water must not be overlooked in these experiments on meadow-land. Guano would require wet weather to bring out its full effect in such a case.-A. H.

(urea, uric acid, &c.), and is that which has already been frequently spoken of under the name of ammonia.

Whoever will take the trouble of instituting a few experiments of a very simple character, for which he requires only a candle or a small spirit-lamp, a plated spoon, and a few cups or wine-glasses, may readily make himself intimate with the properties of ammonia, this extremely important nutrient of plants, and draw from the results of his experiments very useful inferences for the rational treatment of drainings.

First Experiment.-Some litmus-paper must first be prepared, which is needed as a test in the subsequent experiments. Put a small quantity of litmus into a cup, pour over it half a teacupful of hot water, and let it stand for a few hours in some warm place. When it has acquired a dark blue colour, pour off into another saucer the infusion, leaving the slimy substance deposited at the bottom, and soak strips of fine printing or letter paper in it, in order to stain them blue. If the colour of the paper when subsequently dried is still very faint, it must be soaked again. The blue litmuspaper thus obtained is an extremely delicate test of all fluids which are acid to the taste. If a small teaspoonful of vinegar, or two drops of sulphuric acid, are put into one or two quarts of water, and the blue paper is dipped in the mixture, it is almost instantly reddened. The chemist calls such tests reagents, and avails himself of the blue litmus or test-paper as the most accurate reagent for acids. Preserve these strips in a box, because they are gradually deprived of their colour by the light.

Let a portion of the blue paper strips be passed through water weakly acidulated, and dried when they have acquired a distinct red colour. For this purpose only from one to two drops of sulphuric acid, or, what is still better, from six to eight drops of lemon-juice, should be introduced into a pint of water. The red test-paper is the most delicate means of recognizing a class of substances opposed to acids, that is, alkaline or basic bodies. If some wood-ashes or burnt lime is scattered upon a strip of red paper previously moistened, or if a piece of soap is pressed upon it, its original blue colour will be restored after washing off the substances with which it has been brought into contact,-a proof that in

these bodies alkaline matter is contained. In the freshly voided urine of a healthy man, blue paper becomes red,—it is therefore acid; red paper, on the other hand, undergoes no change whatever in its colour. If this urine is allowed to stand in a vessel in some warm place, and is examined every day by means of the test-papers, it will be perceived that after a certain time the blue paper is no longer altered therein, but the red is; the change which this latter undergoes to blue, is a proof that an alkaline body has been generated in the urine. This alkaline body is the above-mentioned ammonia, belonging to the same class of bodies as wood-ashes and lime, but essentially distinguished from them by the circumstance that it is volatile, which lime and potash (the alkaline substance contained in wood-ashes) are not.

Second Experiment.—Pour, in the manner described in page 26, some spirit of hartshorn into a plated spoon, and hold it over the flame of a lamp, so that it will become hot, whilst the vapour ascending from it is allowed to mount into a large tumbler held over it: after some time the tumbler will be filled with an invisible air, which possesses a very pungent odour, and a strip of red test-paper, previously moistened, on being put into the apparently empty glass, will in a few moments become blue. The gas escaping from the hartshorn upon heating is pure ammonia; for the liquid hartshorn is nothing else than water into which a large quantity of ammoniacal air or gas has been introduced, and is thereby held in solution. This ammonia again evaporates, even at low temperatures, from the water, and it is from this circumstance that the hartshorn derives its pungent odour; if the heat is increased, the evaporation is increased, and for this reason the solution, in order that it may not lose its strength, must be kept in well-stopped phials and in cool situations. Putrid drainings possess the closest resemblance to this liquid, inasmuch as they also are to be regarded as a solution of ammonia in water; by evaporation, therefore, they will decrease in strength in proportion to the inattention paid to the coolness of their situation and the closing of the receptacles in which they accumulate.

If two equal quantities of hartshorn are put, one into an open phial, the other into a saucer which is left standing in