CHAPTER X.
Inks.
Examination for determining whether a writing has been done at one time, or added to later, necessitates some acquaintance with the nature and qualities of ink. In the ordinary case the assistance of a chemist is necessary, but an enlarged photograph shows up minute differences with amazing accuracy.
In the majority of instances alterations are made some time after the original has been written, in which case a difference in the shade of the ink will be perceptible, even to the unassisted eye. This is particularly true when the now almost universal blue-black ink is used.
The period required for an addition to become as black as the older writing depends very much upon the character of the paper. If this be smooth and hard, and the writing has not been dried with blotting paper, but allowed to dry naturally and slowly, it will become black much quicker than if the paper be rough and of an absorbent nature.
A fairly reliable test is to touch a thick stroke of the suspected addition with a drop of diluted muriatic acid—as much as will cling to the point of a pin. Apply the drop to the suspected addition and to the older writing at the same moment, and carefully watch the result. The newer writing will become faint and watery, with a bluish tinge almost instantly, but the change will be slower in the case of the older writing, taking ten or even twenty seconds. The longer the period required for the change, the older the writing.
This same acid test is applied to prove whether a writing is in ordinary ink, or has been lithographed or photographed. If the two latter, the acid will have no effect.
On more than one occasion collectors have purchased as original autographs of celebrities which proved to have been lithographed or photographed, but the persons so deceived have generally been inexperienced amateurs.