STUDIES IN MATERIALS The primary object of this paper is instruction; and there are in troduced here certain problems carried along lines which show the particular qualities of the material under consideration. Special at tention is called to the fact that these problems are not introduced merely to illustrate the qualities of the particular material, but to indicate lines of thought to be followed in considering every material.
There are a great many things taken for granted in connection with building material—many old beaten paths which lead one from tradition to nowhere. The sooner the specification writer accustoms himself to testing everything he handles, the sooner he will be master of the situation. If this work is ignored, and he follows only beaten tracks—and the information of "Material Men''—he will be in hot . water most of the time.
in specifying materials, one maxim should always govern: Never specify a quality which you cannot demonstrate exists, or forbid a quality or ingredient you cannot detect. For instance, if you are
not prepared to have a chemical analysis made of the Portland cement don't say anything about sulphur or magnesia; clauses of this kind may sound well, but they may cause you trouble if later you cannot tell anything about the composition of the m, terial. If you depend on the analyses as made by the manufacturers, y ou can depend on it that you will never find a cement with a harmful pei-entage of either.
The problems will be on the following subjects—Sand, Cement, Lumber, Roofs.
In addition to the work along the lines laid out, the powers of ob servation should be so cultivated that in the daily routine, wherever work is encountered, the eye will be ever ready to detect any phase of development in material.