To determine the age of writing by applying bleaching acids and watching results and counting the seconds is a dangerous method. Thick inks will respond to the acids slower than thin, and the time comparisons are misleading.
Safety inks, so-called, designed to resist the action of acids and alkalies have been repeatedly put upon the market, but no such ink has ever successfully challenged the world and proved its title of safety.
Many chemicals are recommended as restorations for faded writing, but these should be avoided as far as possible, as they are liable to stain, disfigure the paper, and in the end make matters materially worse. Familiarity with particular handwritings after some practice will enable the reader to make out otherwise unintelligible words without any other assistant than a powerful magnifying glass.
If the ink is very faint, the simplest and most harmless restorative is sulphate of ammonia, but its loathsome smell once encountered is not easily forgotten. The experiment in consequence is very seldom repeated for the result is scarcely good enough to risk a repetition of so horrible a smell.
The writing on old and faded documents may be restored, by chemical treatment, turning the iron salt still remaining into ferrous sulphate. A process which will restore the writing temporarily is as follows: A box four or five inches deep and long and broad enough to hold the document, with a glass, is needed. A net of fine white silk or cotton threads is stretched across the box at about one half the depth. Two saucers containing yellow ammonium hydrosulphide are placed in the bottom of the box. By means of a clean sponge or brush, moisten the paper with distilled water; then place it on the net with the writing side down. The action of the vapor of the ammonium hydrosulphide will cause the obliterated writing to slowly turn brown, then black. But within a short time after removal from the box the writing will again disappear.
Another method is to wash the document carefully in a solution of hydrochloric acid, one part, and distilled water, one hundred parts. Dry the moistened paper somewhat, leaving it just moist enough to hold a uniform layer of fine yellow prussiate of potash. A plate of glass with a light pressure should be placed on this. In a few hours dry the paper thoroughly, and carefully brush off the yellow prussiate of potash. The writing should come out a Prussian blue. This restored writing will be permanent unless exposed too much to the light.
The hydrochloric acid must be thoroughly removed; otherwise, it will destroy the paper. Crystallized soda, two parts, and distilled water, one hundred parts, in solution, will counteract the hydrochloric acid, if the document is allowed to float on it for twenty-four hours.
DETECTING FRAUD AND FORGERY IN PAPERS AND DOCUMENTS
Infallible Rules for the Detection of Same—New Methods of Research—Changing Wills and Books of Accounts—Judgment of the Naked Eye—Using a Microscope or Magnifying Glass—Changeable Effects of Ink—How to Detect the Use of Different Inks—Sized Papers Not Easily Altered—Inks That Produce Chemical Effects—Inks That Destroy Fiber of Paper—How to Test Tampered or Altered Documents—Treating Papers Suspected of Forgery—Using Water to Detect Fraud—Discovering Scratched Paper—Means Forgers Use to Mask Fraudulent Operations—How to Prepare and Handle Test Papers—Detecting Paper That Has Been Washed—Various Other Valuable Tests to Determine Forgery—A Simple Operation That Anyone Can Apply—Iodine Used On Papers and Documents—An Alcohol Test That is Certain—Bringing Out Telltale Spots—Double Advantage of Certain Tests—Reappearance of Former Letters or Figures—What Genuine Writing Reveals—When an Entire Paper or Document is Forged.