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Show Tenting Cement. - Rough testing of cement, so as to enable en-able a workman to get a crude and imperfect im-perfect idea of its value, is easy. Enough of the pure cement should be taken to make a ball an inch in diameter and mixed with just sufficient water to make it mold readily and be rolled into a ball. Then it should be exposed to the air and left for two hours. At the end of that time it should be set; then it should be put into water and left. It should grow gradually harder, and should show no signs of cracking and crumbling, even when left for ten days. Any cement that does not endure this test is not of sufficiently suffi-ciently good quality to make satisfactory structures; any cement that stands this properly will be generally satiefactory if properly used. In determining how to construct a building, a series of tests is often required that shall show tensile, breaking, twisting, twist-ing, and crushing strength, and also adhesion ad-hesion of the materials used for mortar. No one of these can be dispensed with, since material that will endure one satisfactorily satis-factorily will often fail utterly in another, and hence prove worthless for the use desired; de-sired; but for general purposes the test of cement which is the most valuable is that which determines its tensile strength. Comparative tests of this show the value of cements from different sources better than any othor one test. Professor La Roy F. Griffin, in The Popular Science Monthly. |