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CHAPTEE VI. 



GUANO. 



Composition compared with that of seeds ; small amoimt of potash in it ; 

 its action — Guano and bone-earth, similarity of their active ingredients 

 — Guano acts quicker than bone-earth, or a mixture of the latter and 

 ammoniacal salts ; reason of this — Oxalic acid in Peruvian guano ; the 

 phosphoric acid rendered soluble by its means — Peruvian guano, its effect 

 on the cultivation of corn — Moist guano loses ammonia — Moistening 

 guano with water acididated with sulphm-ic acid ; effect — Inactivity of 

 guano in diy and very wet weather — Rapidity of its action as a manure, 

 on what dependent — Comparison of the effect of farm-yard manure 

 and guano ; effect produced by mixing the two — Guano on a field rich 

 in ammonia — Increased produce by guano, what it presupposes — 

 Exhaustion of the soil by continuous use of guano — Mixture of guano 

 with gypsum and with sulphuric acid — The Saxon agricultural experi- 

 ments ; their results. 



PERUVIAN guano generally contains 33 to 34 per cent, 

 of incombustible, and 66 to 67 per cent, of volatile 

 and combustible ingredients (water and ammonia). The 

 latter consist principally of luric acid, oxalic acid, a brown 

 matter of uncertain composition, and guanine. The 

 uric <icid amounts occasionally to as much as 18 per 

 cent., the oxahc acid generally to 8 or 10 per cent, of 

 the weidit of the pjuano. The relation of uric acid to 

 vegetation is not known, but it is hardly likely that this 

 substance can have a perceptible share in the fertilising 

 action of guano. To account for this action, then, 

 we have only the ammonia and the incombustible con- 

 stituents left to consider. An analysis of two samples of 

 guano, made by Dr. Mayer and Dr. Zoeller, in my own 

 laboratory, showed 100 parts of guano ash to con tarn : — 



