Mineral impurities in paper are not uncommon. Minute particles of iron worn off the machinery, or getting into the stock in the shape of wire stitching, can often be discovered by the use of a magnet test. In photographic papers this must positively be excluded, but in most papers, if the particles do not show as specks, and are not large enough to make trouble for the printer, they are not a serious menace. CHAPTER SIX PAPER-MAKING We have now reviewed the various steps preparatory to the process of beating, and this process is perhaps the most important of all. The output of a mill depends, first, upon the quality of stock which is furnished to the beaters, and secondly, on the way the stock is handled in the beaters. A formula, better known as a “furnish,” is prepared by the superintendent and given to the beater engineer. This tells him exactly how to blend his raw materials. Very few papers are made from one kind of material alone, most papers being a mixture of different fibers, with the addition of mineral filler, sizing and coloring. All the ingredients are put together into the beating engine with a large volume of water similar to a washer, minus the washing drums. BEATING. The process is called beating because it has displaced the original method of maceration by mallets and later by the machine described in Chapter I as a “stamper.” The ultimate characteristics of the paper are dependent upon the handling of the beater roll and the character of the knives. For example, a blotting-paper is made by a quick beating with sharp knives. This cuts the fibers clean and short and leaves them in a most absorptive condition. The very same fibers, treated with dull knives and slowly beaten, would have an entirely different character. Their ends would be teased out and ragged, and in the process of manufacture they would part very slowly from the water absorbed. The paper produced would have the characteristics of a writing-paper, hard and strong. This instance will afford some idea of the wide variation in results which may be brought about by varying the treatment in the beaters. So important is this step in manufacturing that it has been said with a good deal of truth that “the paper is made in the beaters.” After the process has been continued a sufficient length of time, the stuff is emptied into a chest called the “Jordan chest,” because it acts as a reservoir for another type of refining engine known as the “Jordan.” This engine is conical in shape and the inside is lined with knives. A cone-shaped plug, also shod with knives, fits into this shell, and by the turn of a screw may either be moved in or out, thus varying the space between the two sets of knives. By this adjustment the refining of the pulp which flows through the engine is regulated.