. Manures and fertilizers; a text-book for college students and a work of reference for all interested in the scientific aspects of modern farming . also entirely different from those of the of the phosphates studied in the laboratory areartificial products. They are in consequence not of thesame physical character as certain of the phosphateswith which the farmer has to deal. For these reasonsgreat care should be taken in attempting to apply all suchlaboratory findings to the conditions practically met within the field. With this precautionary introduction it may be well tocon
. Manures and fertilizers; a text-book for college students and a work of reference for all interested in the scientific aspects of modern farming . also entirely different from those of the of the phosphates studied in the laboratory areartificial products. They are in consequence not of thesame physical character as certain of the phosphateswith which the farmer has to deal. For these reasonsgreat care should be taken in attempting to apply all suchlaboratory findings to the conditions practically met within the field. With this precautionary introduction it may be well toconsider certain laboratory observations, which may havea direct, or, more frequently, indirect, bearing upon thepractical utilization of phosphates. 353. The action of water on monocalcium phosphate. —As concerns the action of water upon monocalciumphosphate there exist widely divergent differences are believed to be due to the fact thatsome of the monocalcium phosphate employed by thedifferent experimenters contained a little free phosphoricacid, which increased its solubility; furthermore, owing MANUFACTURED PHOSPHATES 209. 210 FERTILIZERS to the hygroscopic nature of the free acid, and to the watertherefore absorbed, the amount of actual monocalciumphosphate employed may sometimes have been less thanwas supposed. From recent investigations it also appears that uponthe addition of water to monocalcium phosphate a cer-tain amount of hydrated dicalcium phosphate (CAHPO4• 2 H20) is formed, and at still higher temperatures eventhe anhydrous salt (CaHP04), which, unlike the hydratedsalt, is insoluble in citric acid. At the same time theresulting solution contains a higher ratio of phosphoricacid to lime, than the monocalcium phosphate. Thisis indicated partially by the equation which follows: — CaH4(P04)2- H20 + H20 = GaHP04 + 2H20 + H3P04- The free phosphoric acid therefore carries with it into thesolution some dicalcium phosphate. The addition ofmore water r
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfertili, bookyear1913
