The Elements of economic geology

Bibliographic data

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

Usage license:: Get license information via the feedback formular.

Chapter

Document type:: Monograph

Structure type:: Chapter

Title:: Part III. Earthy minerals

Collection:: Economics Books

[76 ECONOMIC GEOLOGY is not protected from the rise of water by a damp-course. The solvent effect of rain-water is mainly due to acids de- rived from the atmosphere. The most important is carbonic acid (CO,) ; it converts the insoluble unicarbonate of lime (CaO, CO,) into the bicarbonate (HyCaCyO4, ie. CaO, 2C0,, H,0), which is removed in solution, causing the crumb- ling of rock with a calcareous cement. The silicates of lime and of the alkalis are also converted into carbonates and removed in solution. The air of industrial cities includes sulphuric acid, as coal generally contains in pyrites more than -5 per cent. of sulphur, and combustion of that amount produces 35 Ib. of sulphuric acid per ton of coal. Building stones are also attacked by sulphuric acid derived from sulphates in the mortar which are due-to pyrites in the fuel used to burn the lime. The insertion of new cement between old stones may ruin them, as carbonate of lime may be deposited in the pores and have a disruptive effect. The air receives nitric and hydrochloric acids from factories, nitric acid by the oxidation of nitrogen by lightning, and chlorides from the sea. Common salt, sodium chloride, is introduced into the air by the evaporation of sea spray and the minute winged crystals are blown far inland. The salt is dissolved and soaks into porous stone, which it weakens as its crystallization forces the grains apart, while it keeps the surface damp by absorption of moisture from the air. Building stones are also attacked by agencies which act mechanically. The wind often has a speed of 30 to 60 miles an hour and sometimes of over 100 miles (as in Glasgow, 28 January, 1927), and like a sand-blast it hurls against buildings sharp fragments of quartz from the road stones and jagged shreds of iron from cart wheels. Soft particles at a high speed have a cutting effect, for soft wheaten flour eats into quartz or topaz when flung against it bv a sand- blast. Sudden changes of temperature fracture rocks. When water freezes in the pores of a rock its expansion forces off “ frost-flakes.” The chilling of rock in a tropical desert after sunset throws off similar flakes, and sudden exposure to the sun produces insolation flakes. The freezing of water in a stone has been estimated as having a destructive effect

Access restriction

Copyright

fullscreen: The Elements of economic geology

Monograph

Chapter

Table of contents

Download

Monograph

Chapter

This page

Image fragment

Citation links

Citation recommendation