4. The balmier test affords a simple means of determining the goodness of guano. We may either boil half an ounce of dried guano in 5 or 6 oz. of water, and filter the solution while hot, or we may place the guano on a filter, and continue to pour boiling water over it, until the drops that come through the filter cease to yield any residue when heated to dryness on a glass slip held over the spirit-lamp. As a general rule, the larger the quantity of guano that is dissolved in hot water, the more ammonia salts does it contain, and the better it is. In the best or Peruvian guano, the insoluble resi due ranges from 50 to 55 per cent, while in the inferior varieties it may amount to 80 or 90 per cent.
• 5. The acid test serves to deteCt the chalk which occurs id 'the 'riot:A.1a Mooria guano, • and is used as an adulteration for other varieties. Mix the powdered guano with a little water, and add a little hydrochloric acid or strong vinegar. If chalk is present, effervescence from the liberation of carbonic acid occurs.
6. The weight affords the easiest test for the purity of guano. According to prof. Anderson, a bushel of pure Peruvian guano should not weigh more than front 56 to 60 lbs.; but according to most authorities it should weigh almost exactly 70 lbs. If heavier than 73 lbs., it is adulterated with clay, marl, sand, or some other impurity.
If the value of a manure be calculated, as is done by Boussingault and other eh( m ists, according to the amount of nitrogen which it contains, one ton of good Peruvian guano is equal to 33i- tons of farmyaremanure, 20 tons of horse-dung, 381 tons of cow. dung, 221 tons of pig-dung, or 141 tons of human excrement.
When we consider what guano is—viz., that being the more or less decomposed excrement of fish-eating birds, it consists essentially of the ash constituents of the flesh of fish, together with anunonia salts—we need not wonder that its application to the laud as a manure should so largely increase its productiveness, "for guano," says Liebig, " contains not only the mineral elements which a soil must possess to produce corn, but also in the ammonia an indispensable element of food which serves to quicken their action, and to shorten tlte time required for their assimilation. On many fields, the ammonia in the guano may, if the weather prove propitious, possibly affect the assimilation of double the ordinary quantity of these mineral constituents, and thus render the amount of produce yielded in one year equal to what would have been oth erwise obtained in two years by these mineral matters alone." The introduction of guano into this country as a manure is comparatively recent. In 1840 only 20 casks of it were imported. In 1841 the earl of Derby—then lord Stanley—spoke strongly in its recommendation at the Liverpool meeting of the royal agricultural society of England; and from that time it has come rapidly into use, as may be seen by the following table'of imports: As the chemical composition of natural guano is known, an artificial guano may be read ily compounded by the admixture, in due proportions, of its constituents. The following mixture, recommended by the late prof. Johnston, forms one of the best imitations of guano. 132i His of it being equal in power to 1 cwt. of good Peruvian guano: Mix 781 lbs. of bone-dust, 25 lbs. of sulphate of ammonia, 11 lbs. of pearl-ash, 25 lbs. of common salt, and 21- lbs. of dry sulphate of soda. All these materials, excepting the bone-ash, may be procured from any druggist.
Guano was largely used for all the cultivated crops on the farm, and is yet, as far as it can be procured. Being a high-priced, but concentrated and powerful fertilizer, in ordinary farm-management it is applied with more economical results to some crops than to others. On grasses proper, it is sown broadcast in the early part of spring, when vegetation begins to start. At this time the roots take it up, and prevent it front being washed out of the soil. Clover, on the other hand, being a deep-rooted plant, is supposed by some to be best dressed with it in autumn, before vegetation is stopped for the season. The roots store up the active principles of the manure till spring, and the pla'nts are in is far more vigorous state for the summer growth. From two to three cwts. of guano per acre is the common allowance for grasses intended to be cut for hay, bat the Dalian variety of rvegrass will sometimes bear a large quantity with beneficial results. Guano is rather too soluble to be applied to early autumn sown wheat. It both stimulates the plant too much before winter, and is apt to lie partially washed out of the soil with the winter rains. In moist springs. when there are abundance of rains to wash it in, guano forms an admirable top-dressing for winter wheat. For spring sown wheat, and other cereals, no manure has a more powerful influence. The closer that it is put to seed, the better. The common dressing is from three to four cwts. to the acre for cereals. It should be kept in mind, in regulating the quantity, that the stronger the land is. the larger the quantity that can be applied with a prospect of yield ing a profit. The same principle should be observed in its use for the turnip crop. As much as from four to six cwts. may sometimes be beneficially applied to early sown turnips on deep and able soils, while two to three cwis.. when farmyard manure is given, will in general prove the most economical quantity. Guano is apt to produce too much hoot when it is apifiied in large quantities to late sown turnips. and to pre vent the formation of bullA Iu such circunistancoMphosphoric .manures will often yield better crops at less expense. When guano is applied to beans or potatoes, they should be also dressed with farmyard manure.' Guano does not possess the power of sustaining the healthy growth of these plants on most soils without something else in addition.
Mixed with rough bones, guano is valuable, applied above dung for turnips, and a great deal of it has been so used. Its value as a fertilizer was so highly appreciated, and its use so extensive, that farmers got not a little alarmed and disappointed at the diminutlon of the genuine Peruvian guano supplies. Agriculturists of necessity betook themselves of late to various artificial substitutes for Peruvian guano, but the results are not generally so satisfactory. Farmers learned, in the spring of 1874, with satis faction, of the discovery of new guano deposits on the coast of Peru. For the Peru vian government, Mr. M. H. Thierry explored the new deposits, and he estimated the total quantity at 7,500,000 tons. Of seven different places mentioned as containing that deposit., Pabellon de Pica, having 5,000,0o0 tons, is the principal. Careful analyses made of the new guano on behalf of the government proved it equal in quality to the guano of the Chincha islands.