Répertoire des administrateurs & commissaires de société, des banques, banquiers et agents de change de France et de Belgique

The Elements of economic geology

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Monograph

Identifikator:: 1751319059

URN:: urn:nbn:de:zbw-retromon-129553

Document type:: Monograph

Title:: Répertoire des administrateurs & commissaires de société, des banques, banquiers et agents de change de France et de Belgique

Place of publication:: Paris [u.a.]

Year of publication:: [1926]

Scope:: 1316 S.

Digitisation:: 2021

Collection:: Economics Books

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Chapter

Document type:: Monograph

Structure type:: Chapter

Title:: Droit de timbre. - taxe de transmission - timbre de facture. - taxe de luxe. - taxe d'affichage. - droit d'enregistrement. - droit de succession

Collection:: Economics Books

BUILDING STONES AND ROAD METALS 179 and observing the rate at which coloured water rises into it and also by determining the amount absorbed by weighing a test piece before and after complete immersion. A stone with attractive qualities may be unsuitable owing to high porosity where rain is flung against the buildings by high winds. Microscopic Examination—Panama “ Breaks "—These tests should be supplemented by microscopic examination of thin sections which reveals qualities that cannot be inferred from chemical analysis or crushing strength. The method quickly determines the chemical composition of coarse- grained rock ; it shows whether the felspar is potash-felspar, which is generally more durable than the soda- and lime- felspars. A bulk chemical analysis shows the proportions of the constituents; the microscope shows how they occur. For example, the Reigate sandstone, which was used for parts of Westminster Abbey, perishes in a city atmosphere, although it contains 80 per cent. of silica, for its cement is its 10 to 15 per cent. of carbonate of lime; whereas the Chilmark Stone with 79 per cent. of carbonate of lime better resists weathering because its cement of silica protects the calcareous particles. The experience at the Panama Canal 1 shows the value of microscopic examination of stone, and that crushing strength is not always a reliable guide. The International Board of Consulting Engineers for the Panama Canal in 1906 expected, from crushing tests on bore samples, that the banks would stand at a slope of three vertical to two horizontal, and would be stable in a cutting 245 feet deep. Yet the bottom of that excavation began to upheave when the depth was only 65 feet. These upheavals, or “ breaks” continued in 1912 when the slope had been reduced to one vertical to 3% hori- zontal. The weight of the banks forced the underlying mudstone, after water gained access to it, to upflow into the excavation. The upheavals were sometimes fast; a heavy steam shovel was uplifted g feet during an afternoon, and some machinery raised 11 feet in 10 minutes; in some cases the uplift recurred seven times before all the mobile layer had been squeezed out. Y Reports of the Isthmian Canal Commission, 1899-1911 Vaughan Cornish, Edinb. Review, Jan. 1913, pp. 21-42, and Geog. Journ., xli, 1913, pp. 239-43.

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