principally present ? as an ammoniacal salt? as a nitric acid salt? or as an organic substance of easy or of difficult decay? By the reply to the first inquiry he is placed in a position to calculate from the seven points above named, the approxi mate money value of the manure in question, whilst from the subsequent answers he acquires tolerably certain information as to the slow or rapid action he may expect in its use. Having obtained the analysis, he can compute, with the aid of the preceding valuations, the price to be attached to each separate substance, and add together these single

sums.

The following examples may be useful in making clear this operation, and at the same time offer a standard for a comparison of the present market value of the better-known artificial manuring agents with their value as ascertained by this method.

Note. The prices and values given in the text must be taken only as data for estimating the comparative manuring values. The actual prices differ much here and on the continent, and also at different times. The table of prices given in the note at p. 110, will serve as a guide in checking the above estimates for practical purposes.-ED.

VIII. GUANO.

Of those auxiliary manures at the command of the German farmer, guano occupies the first and most important position; not merely because it is the most expensive and the most powerful, but also and more especially because it forms an excellent addition to all other manuring agents, natural as well as artificial, imparting to them a greater activity, that is, by causing them to be more rapidly and certainly effica cious. In most German states guano is still almost unknown as a manure, although the extraordinary results which English agriculture has achieved by its instrumentality ought to excite zealous imitation. A manure that has already sustained in England a trial of ten years, and in procuring which English farmers have expended yearly from £1,000,000 to £1,500,000, must not be considered so unpractical and unprofitable as many German agriculturists continue to believe. It is not saying too much, when it is affirmed that two means contributed to carry English agriculture successfully through the crisis occasioned by the repeal of the corn-laws; and that these two means were guano and draining.

But even in Germany there are individual districts which testify that German agriculture, in precisely the same way

as English, may derive the most extraordinary advantages from the employment of guano. In this respect the kingdom of Saxony may be considered the first; for during the past year this country consumed more of this manure than all the remaining states of the German Zoll-verein together, its annual consumption being about 30,000 cwt.; and an experience of nine years has already brought it into such extensive use, that thousands of farmers may now be found who manure with guano. In the face of such facts, the objections most frequently urged against manuring with this agent that it is too expensive, and evanescent in its action must lose their weight. Guano is certainly expensive; but if one hundred-weight of this substance produces an effect equal to that of three or four loads of ordinary muck, it is obvious that it will remunerate as well as the latter, and even still better; its operation is indeed quickly over, but if it acts so vigorously, that, even in the first year of its application, the capital expended is restored with abundant interest from the soil, then its slighter after-operation is, it may be presumed, not so great an imperfection after all.

Besides these objections, I have often heard from farmers that the reason why they did not employ guano was the apprehension that they might obtain bad, spurious, or adul terated merchandise. This fear is certainly well founded; but equally well founded is the statement, that chemistry offers a means by which the farmer may easily and confidently protect himself against disappointments or frauds of this description, if he will only take the trouble to institute a few simple tests, such as are specified at the conclusion of this chapter.

1. SOURCES AND CONSTITUENTS OF GUANO.

Guano is composed of the excrements of sea-birds, which have accumulated in the course of time, in layers of greater or less depth, upon uninhabited islands and rocks. Good guano comes to us from those zones of the earth in which it never, or at least extremely seldom, rains, and from such islands as are sufficiently elevated to prevent the overflowing of sea-water; for if either happened, the best and most effi cacious portions of the guano would be dissolved and washed away. If a dung-heap is suffered to lie without attention.

for only a few years, with the sun shining upon it, the air driving through it, and the rain washing it away, what will at last be left of it? Not much beyond a few earthy or mineral substances, which could not be dissolved or volatilized. Such washed-out and bad guano is very often found in commerce, and against it the farmer must be upon his guard. Amongst these are the cargoes which come to us from Chili and Patagonia, since these countries are inundated with heavy rains. In like manner, those kinds of guano now met with under the name of "African" must be enumerated here; whereas the guano brought some years since from Africa, which bore the name of "Ichaboe guano," might be admitted as of good medium quality.

The best guano comes from the rainless region of Peru, which lies beneath the 5th and 20th degree of south latitude. Here it covers the rocky surface of the cliffs and islands in layers of very various thickness, in a similar way to our own clay strata. The depth or thickness of these layers varies from one or a few yards to twenty and thirty, and sometimes even more. In the first year in which a layer of guano is deposited it has a white colour, and is called guano blanco; this is generally acknowledged to be the best, and is bought from the Peruvians, who esteem it highly, at double the price which is given for the brown. It possesses nearly the same constituents, and produces the same effects, as our pigeon-manure; but its action is still more energetic, be cause it is richer in nitrogenous substances. The reason of this difference consists in the difference of food. The marine birds, whose excrements furnish guano, live upon fishes, whilst our pigeons take only vegetable nourishment; an animal diet is always richer in nitrogen, and furnishes for this reason a manure that abounds more in this element than one furnished by a vegetable diet. The layers which succeed to the white have a light grayish-brown colour; still deeper down, they become darker, and at the lowest part rust-coloured; the lower layers, moreover, are inva riably more compact than the upper. It is evident that the inferior layers are the oldest; putrid decomposition has advanced farther in them, and hence feathers, egg-shells, and similar remains are no longer found, whilst in the upper layers they are of frequent occurrence.

But will not these layers of good guano be speedily exhausted by the increasing demand? This apprehension I have already heard from many farmers, but it is not, after all, very urgent or alarming. According to the survey recently instituted by the Peruvian government, the deposit of guano now existing in South and Middle Peru contains a store of more than 25,000,000 tons. This supply will hold out yet a considerable time*.

The very apprehension, however, that the guano may come to an end, should impel the farmer to exert himself, that he too may participate in the advantages which rational agriculture is able to derive from this substance before it is too late. For it is beyond dispute that those countries which are first in securing its possession will obtain the greatest advantage, inasmuch as they will attain far more quickly to an increased revenue from the soil than those which follow later, and inasmuch as they will first arrive at that state of cultivation in which they can do without its assistance. This high cultivation will be attained when, through the augmented produce of fodder and straw produced by means of auxiliary manures, as much natural manure is produced as is requisite plentifully to manure the entire area of the farm. Saxony numbers already, particularly in Upper Lusatia, many farms of this description.

The guano at present met with in commerce is brought to us either from America or Africa; the American, under the names of Peruvian, Bolivian, Chilian, Sea-Island, and Patagonian guano; the African, under the designation of Cape and Saldanha Bay guano. Of these varieties, only the Peruvian is to be regarded as good guano; all others are of little worth, and more or less washed out.

Until the last few years, as has been previously mentioned,

*It was apportioned thus (1850) :

Northern district.

Chinchas Islands.

Southern district..

854,000

18,250,000

7,621,000

26,725,000

Admiral Moresby states that English surveys reduce the store of the Chin chas Islands to 8,600,000 tons (1853).-See Journal of Royal Agric. Society, xiv. p. 383.-ED.