The Elements of economic geology

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Monograph

Identifikator:: 1773832379

URN:: urn:nbn:de:zbw-retromon-172798

Document type:: Monograph

Author:: Gregory, John W. http://d-nb.info/gnd/11683014X

Title:: The Elements of economic geology

Place of publication:: London

Publisher:: Methuen

Year of publication:: 1928

Scope:: XIV, 312 S.; graph. Darst.

Digitisation:: 2021

Collection:: Economics Books

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Document type:: Monograph

Structure type:: Chapter

Title:: Part III. Earthy minerals

Collection:: Economics Books

200 ECONOMIC GEOLOGY indispensable for high explosives most nations will probably manufacture them, so as to be independent of an imported supply. PuospuATES 1 VaLuE anD Use oF ProspaaTes—Phosphate of lime is a much scarcer mineral than carbonate of lime; it is of high importance as a fertilizer, being especially useful in the growth of grain, Burnt bones had long been used in China as manure, and their value is explained by Gahn's dis- covery in 1769 that bones contain phosphorous; but as bone phosphate is insoluble the fertilizing effect of bones was attributed to their gelatine, until in 1843 experiments by the Duke of Richmond showed that ground bones with and without their gelatine were equal in fertilizing value. Normal phosphate of lime (CayP,0q) is insoluble; but it was dis- covered by Lawes in England and by Liebig in Germany, that the action of sulphuric acid on bones and mineral phos- phate converts them into superphosphate or acid phosphate (CaH4(POy2, H,0) which is soluble and usable as plant food. The exhaustion of many wheat fields in North-western Europe about that date led to fears of famine. Beds of phosphatic nodules occur in the S.E. of England, and their conversion into superphosphate rendered them available for the refertilization of the European grain-fields. Emerson, the American philosopher, suggested that spendthrift agri- culture might be saved by agricultural chemistry * offering by a teaspoonful of artificial guano to turn a sandbank into corn; while Liebig, with generous enthusiasm, declared that England had in its mineral phosphates, a source of wealth equal to its coal-fields. The supply of English phos- phate was disappointingly small, and the industry became dependent upon imports from warm temperate and tropical cegions. The commercial phosphates are due to the concentration of phosphoric acid by various processes (Fig. 53). The primary source of the phosphorus is the apatite in igneous rocks. It is a tricalcic phosphate of lime (Ca,P,04), LA general account of the geology of phosphates has been given by che author, 77. G. Soc. Glasgow, xvi, 1917, pp. 116-63.

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