Engineering and Contracting, Vol. 28

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Excerpt from Engineering and Contracting, Vol. 28: A Weekly Journal for Civil Engineers and Contractors, July-December, 1907For recording the formation 'in detail, a sample of the ground passed through should be taken every 20 ft. Or at every change in the formation. This sample should be marked and put in bottles for future reference. After the ore is entered, most careful samples should be taken every 3 ft. In prospecting for gold, silver or copper these samples should -be put in an iron tub and the water evaporated over a slow fire, after which they should be quartered down and sent to the chemist for the determination of their value.In some cases 'it is even desirable to have a photograph of'the hole and the formation penetrated. An apparatus has been perfected that will' give a very good photograph of a hole, and show the ore in view if it is plain enough to make an impression. Photographs have even been taken with a moving film giving a con tinuous impression of the hole for over 100 ft. While care should be exercised in taking samples of zinc and lead it is not necessary to spend the same amount of time on them, it is seldom necessary to know their average value per ton. Only the extent of the ore body.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully, any imperfections that remain are intentionally left to preserve the state of such historical works.