Again, Mr. E. S. Fickes, of Steubenville, Ohio, has recently made[17] a large series of valuable tests of both paving and building bricks, in which he shews the connexion between the power of absorption and the strength of the materials experimented with. Mr. Fickes’ more important conclusions are:-- 1. The strength of the building brick, both transverse and crushing, varies in tolerably close inverse ratio with the quantity of water absorbed in twenty-four hours. The strongest bricks absorb the least water. 2. Good building bricks absorb from 6 to 12 per cent. in 24 hours, and with no greater absorption than 12 per cent. will ordinarily show from 7,000 to 10,000 or more pounds per square inch of ultimate crushing strength. 3. Poor building bricks will absorb one-seventh to one-fourth of their weight of water in 24 hours, and average a little more than one-half the transverse and crushing strength of good bricks. 4. An immersed brick is nearly saturated in the first hour of immersion, and in the remaining 23 hours the absorption is only five-tenths to eight-tenths of 1 per cent. of its weight, as a rule. These experiments are of much interest and are probably approximately correct; but we venture to think that if the absorption experiments had been carried out in a different manner, the results would have been still more valuable. Long before the publication of the results of the last mentioned series of experiments, the present writer had discovered the close connexion which subsists between the relative absorptive capacity of bricks and their strength; a slight correction must be applied for specific gravity. We are not prepared to enter into this subject at any length, but it may be observed that we should not have arrived at such close results had we experimented in the same way as the American authors just quoted (or others, for the matter of that). When you completely immerse a brick in water you prevent the escape of air to a very large extent from the pores in the interior of the brick. An old-fashioned way of overcoming this difficulty, was to place the brick in the receiver of an air-pump and exhaust the air, subsequently immersing the brick. This latter method certainly possessed the merit of enabling the experimenter to arrive at total absorption very rapidly, but it did not imitate natural processes any more than does the thorough immersion of the brick in water.