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74 carried out, a sample known to be satisfactory being tried by the side of the suspected sample.

Fortunately papermakers do not often offend by sending supplies which are out of the square. It does, however, sometimes occur that one edge of the paper is not quite true; folding a sheet in half, with the short edges coincident, will show the extent of deviation from squareness. For ordinary purposes it may not be material if one edge of the paper is one-eighth of an inch out, but if the sheet has to be backed up, care must be taken to feed the longer side into the grippers and to place the side lay, when backing up, at the opposite side exactly at the same point as when first fed. This, of course, is the printer's rule, and in such cases it must be rigidly observed. When paper is fed to the narrow edge, as when two sheets of demy are laid on a double demy machine, the square edge must be the lay edge, or the register of the backing forme will be impossible. For colour work the only safe rule is to trim the two lay edges of all the paper, and, if necessary, to use a larger paper to allow for the trim.

Electricity in paper causes delay in feeding, the sheets sticking together, necessitating an undue use of the cylinder stop. As the paper is reeled at the end of the papermaking machine, electric sparks are frequently to be observed, owing to the electricity generated by friction of the dry paper. A large quantity of the electricity is extracted, but some thin papers with high surface will retain a fair amount, and sheets cling together. Paper which has been exposed for maturing will not give this trouble, and thick papers, even if electrified, do not usually call for special treatment. Elaborate methods have been suggested for discharging the electricity in the paper, but it is a difficult matter, and the most satisfactory plan is to set