.PORTLAND CEMENT is usually specified for general construction work. It is so named because, after it has been liquefied, cast, and cured, it is said to resemble a kind of limestone from the Island of Portland off the English Coast. It is a type of cement, not a trade name. Several manufacturers make it, using the fixed standards of the U. S. Government and the American Society of Testing Materials. It is usually packed in paper bags weighing 94 pounds, each equalling 1 cubic foot, dry measure. Although it is obtainable also in barrels containing the equivalent of 4 sacks, these are seldom practical for the amateur's use. Cement must never be stored in damp places, on concrete floors, or on the ground. It may absorb moisture through the bag even in comparatively dry basements. Opened bags will allow the cement to take up moisture even more quickly, absorbing it from the air, which will make the cement lumpy or solidify it altogether, thus rendering it unfit for use. Even unopened bags will become lumpy or solidify if not used within a reasonable length of time, particularly in humid climates; so it is a good plan to figure carefully and not order more than can be conveniently used at one time, and thus avoid the perils of storing it. On the other hand it is downright disconcerting, to say the least, to run short of cement if you are a weekend craftsman. It is better to have an extra bag in case it may be needed on a Saturday afternoon or Sunday if you are working then, for those are days when it is usually impossible to find a place from which it can be bought. If it is not used, you can always put it to good use the next weekend or the following one. Elsewhere in this text you will find explained the method of making stepping stones and paving blocks (Chapter XVII), and it is recommended that any leftover concrete can be poured into the forms for these if they are kept in readiness.