Page:The American Cyclopædia (1879) Volume VIII.djvu/296

 GUANO Ci iNSTI 11 1 A l>. Jtrvli ll.nl. CONSTITUENTS. Jar vli i.land. IHker'. i I u,.|. Water "ii-iiii 17-50 Water 7-60 l-:,n Oix- inutttTiiiul nuDon'l Mlta Phosplu Hulph. of lime. Alkallno salts.. is-oo 21-00 .VJ-iiO 4-00 4-00 10-00 4-00 Or-Mlli.' IMatt.T Soluble halts .. Sulph. of lime. Phot, of Una*.. Curbs. & silica 4-00 2-60 6-00 81-00 11 Mill h-oo 7C-80 I'M Total loo-no IIHI-IHI 100-00 Analyses and calculations like those given ought to ho made in entering upon all large purchases of guano, as well on account of the great natural diHercnces in the qualities of the various kinds, oven from the same locality, as of i lu- gross adulterations which are largely and most ingeniously practised; suhstances of no value as fertilizers being intermixed with the genuine article, so as to very materially reduce its value. Full half the guano sold in England is said to he thus deteriorated. The analyses, moreover, are of importance, as they Indicate the most advantageous methods of applying the guanos, and for what crops and what soils tin are best adapted. But for the knowledge of their composition thus acquired, tin- hot Peruvian guano, rich in ammonia, might be extravagantly employed upon soils that would he almost equally benefited by the cheaper qualities, of which the phosphates are tin- chi<-f fertilizing ingredients. Upon light soils especially, the ammoniacal guano may be used to waste, owing to the little obstruction they present to the escape of its volatile and very soluble portions ; the full benefit of these will bo secured only in the strongest soils, or in composts prepared with the view of their absorption and retention. In such mixtures guano is used most advantageously. Of itself alone it may furnish all the ingredients re- quired by the plants ; but its activity and eva- nescence need to be chocked, and on account of its caustic quality care should bo taken that it be not brought in direct contact with the seed. The quantity of best guano that should bo employed to the aero is generally rated at from ;{ to 5 cwt. ; and it should bo applied in wet weather, when the rains diffuse it equally through the soil. The Peruvians, it is s:iiii, irrigate immediately after applying it. They use it only for Indian corn and potatoes, bury- ing about half a handful near each root when the plants are perhaps half grown, ami add- ing some aicr "to fix the guano." In this country it is found to bo an excellent top dressing for grass and young corn, and is a most efficient manure for Ml the root crops. The search for new localities of guano led to the discovery in I s.V, ,,f animal deposits of the same original nature' upon the groups >f islands lying oil' the coast of (iuiana and Veiie/.uela. Immense lloeks of sea fowl fre- quent, these i>laiids for the purpose of laying their C-L'S. lint, bring in the region of the tropical rains the deposits of, -creinent and other organic matters are subject to chemical changes, from which result singular products, renr different from those of the earthy guano of the dry islands of t he Pacific. The principal S'OUps which furnish these products are l.os onges (Monks 1 island), Kl Roque, and Centi- nella. Some of the islands are low, and strewed with sand, which is made up of comminuted coral, madrepore, and shells, in which the birds lay their eggs. Others rise in peaks to the height of 800 ft., and upon these are strati- fied rocky layers of metamorphio guano, some- times covered with the deposits still in process of accumulation. Several qualities of guano are recognized, one of which is arenaceous, in grains as coarse as mustard seed, light yellow- ish brown or nearly white when dried, exha- ling an odor not ammoniacal, but like that of freshly dug earth. Its average composition is thus stated by Dr. A. A. Hayes: moisture, after drying, 4'40 ; organic matter, 0'4 ; hone phosphate of lime, 40-60; carbonate of lime, 39'80 ; phosphate of magnesia, 1 -20 ; sulphate of lime, 0-80; sand, 0-21; traces of chloride and sulphate of soda; total, 99-41. The am- monia or nitrogen in the organic matters does not exceed 2 per cent, of the whole. Another variety is in aggregated grains, the iirst step in the change of the material into rock. It, dinars in composition from the preceding principally by loss of carbonate of lime and increased proportion of bone phosphate. A third va- riety is a solid rock, which forms a crust some- times 2 ft. thick over the lower portions of the deposit, and is the product of the change that has taken place upon the surface of the mass. Its composition is somewhat variable at differ- ent localities; but it is every where distinguished by the disappearance of carbonate of lime and largo increase in the proportion of phosphate and sulphate of lime. The carbonate of lime has been decomposed by the acids generated in the fermentation induced by the moisture at the prevailing elevated temperature, and with other soluble matters has been removed by the rains. The passage of the gaseous ex- halations through the mass, gradually thicken- ing as its aqueous portion evaporates and the salts gather at the surface, renders its structure porous and cellular, and so much like that of some trachytic rocks that the substance' has been mistaken for one of igneous origin, or at least metamorphosed by heat. The granular structure has given place to a compact, close texture, and a mineral appearance and hard- ness closely approaching that of feldspar; and in some specimens are observed angular frag- ments and grains hardly to be distinguished by tin- eye from epidote. Tin- external surface has an uneven weathered appearance like that of trap rock, and is of a lighter color than the body of the rock within. Various analyses have bec'ii made of this substance by ditl'erent chemists, and it is found to consist principally of phosphoric acid and lime, the former gener- ally raniring from 87 to 40 per cent., and the latter from :;: to 1 1 per cent., of which a small
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