Excerpt from Minutes of Proceedings of the Institution of Civil Engineers, Vol. 27: With Abstracts of the Discussions; Session 1867-68 Among the many substances that have been recommended as filtering materials, the most prominent, besides charcoal, are those termed magnetic carbide, and silicated carbon. Believing, there fore, that the subjection of these substances to a similar set of experiments to those on charcoal, already described in the Author's original Paper,2 would be a matter of some interest, both a magnetic carbide and a silicated carbon filter were procured from the agents appointed for their sale. Having first washed them with distilled water, 8 gallons of pump water were passed through the former, and 12 gallons through the latter, at the rate of 1 gallon in four hours,3 with the results given in Tables 7 and 8; which exhibit, moreover, the amount of hardness, before and after boiling, as obtained by Dr. Clark's process. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This 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.