If the reverse be the case, the opposite conclusion may be drawn.  Blots are sometimes used by ignorant persons to conceal the improper manipulation of the paper, but they are not adapted to aid this kind of fraud, and least of all to conceal erasures.

The decision as to whether they have been made legitimately and before a paper was executed, or subsequently to its execution, and with fraudulent intent, must be arrived at by a comparison of the handwriting in which the words appear, the ink with which they were written, and the local features of each special case which usually are not wanting.

To determine whether or not papers contain erasures the suspected document should be examined by reflected and transmitted light.  Examine the surface for rough spots.  Forgers after erasures frequently endeavor to hide the scratched and roughened surface by applying a sizing of alum, sandarach powder, etc., rubbing it to restore the finish to the paper.

Distilled water applied to the suspected document at the particular points under examination will dissolve the sizing applied by the forger.  If held to the light the thinning will show.  The water may be applied with a small brush or a medicine dropper.  Water slightly warmed may be used with good results at times.

Alcohol, if applied as described for water, will act more promptly and show the scratched places.  It may be well to use water first and then alcohol.

To discover whether or not acids were used to erase, if moistened litmus-paper be applied to the writing, the litmus-paper will become slightly red if there is any acid remaining on the suspected document.  If the suspected spots be treated with distilled water, or alcohol, as already described, the doctored place will show, when examined in strong light.

Which of two inklines crossing each other was made first, is not always easy of demonstration.  To the inexperienced observer the blackest line will always appear to be on top, and unless the examiner has given much intelligent observation to the phenomenon and the proper methods of observing it mistakes are very liable to be made.  Owing to the well-known fact that an inked surface presents a stronger chemical affinity for ink than does a paper surface, when one ink-line crosses another, the ink will flow out from the crossing line upon the surface of the line crossed, slightly beyond where it flows upon the paper surface on each side, thus causing the crossing line to appear broadened upon the line crossed.  Also an excess of ink will remain in the pen furrows of the crossing line, intensifying them and causing them to appear stronger and blacker than the furrows of the line crossed.