It is probable that ink and pencil alterations and erasures are more frequently made with a sharp steel scraper and ink-erasing sand rubber than otherwise.  By these methods the evidence—­first, the removal of the luster or mill-finish from the surface of the paper; second, the disturbance of the fibre of the paper, manifest under a microscope; third, if written over, the ink will run or spread more or less in the paper, presenting a heavier appearance, and the edges of the lines will be less sharply defined; fourth, if erasure is made on ruled paper, the base line will be broken or destroyed over the scraped or rubbed surface; fifth, the paper, since it has been more or less reduced in thickness where the erasure has been made, when held to the light will show more or less transparency.  When erasures have been thus made the surface of the paper may be resized and polished, by applying white glue, and rubbing it over with a burnisher.  When thus treated it may be again written over without difficulty.  When erasures have been made with acids, there is a removal of the gloss, or mill-finish; and there is also more or less discoloration of the paper, which will vary according to the kind of paper, ink, and acid used, and the skill with which it has been applied.  If the acid-treated surface is again written over, the writing will present a more or less ragged and heavy appearance, if the paper has not been first skillfully resized and burnished.  It is very seldom that writing can be changed by erasure so as not to leave sufficient traces to lead to detection and demonstration through a skillful examination.

Upon hard uncalendered paper erasures by acid when skillfully made are not conspicuously manifest, nor when made upon any hard paper which has been “wet down” for printing, since the luster upon the paper would be thereby removed, and, so far as the surface of the paper is concerned, there would be no further change from the application of the acid.  This applies to a wide range of printed blank business and professional forms.

A forgery consists either in erasing from a document certain marks which existed upon it, or in adding others not there originally, or in both operations, of which the first mentioned is necessarily antecedent to the last; as where one character or series of characters is substituted for another.

The removal of characters from a paper is effected either by erasure (seldom by pasting some opaque objects over the characters, painting over them, or affixing a seal, wafer, etc., to the spot where they existed) or by the use of chemical agents with the object of dissolving the writing fluid and affecting the underlying paper or parchment as little as possible.

If the erasure be effected by scratching or rubbing, this removes also the surface of the paper, which consists of some sort of “size” or paste with resin soap, which is pressed into the upper pores to give the paper a smooth appearance, and to prevent the writing fluid from “running,” or entering the pores and blurring the edges of the lines.