tion of important documents by the use of strengthening bands, inelegant blots, or over elegant penmanship, characterized by a great display of flourishes, are tricks of the trade as of yore; and when they are associated with scientific accomplishments, they are the more deceptive. The chemical agents most usually employed in forgery are muriatic acid, citric acid, oxalic acid, common salt, and other substances containing chlorine, and the chemicals of photography.

In view of the foregoing circumstances, the examination of suspected forgeries may be facilitated by dividing the processes into two classes, namely, physical and chemical.

I. PHYSICAL EXAMINATION.-In the physical examination of written instruments, semi-transparent spots or lines, strengthening strips or entire new backs, blots, heavy or rough lines, interlineations attested with ink of a different shade of color from that used in the main composition, or flourishes of penmanship, are all suspicious conditions. The forger, in order to hide the semi-transparency of an erasure, usually wears the paper in the line of it, by forced creasing, and then applies a strengthening strip or new back. "Worn out lines," or those which have been inserted in the place of others removed, are often mended in the same way. Torn edges or rents, as the effect, or instead of erasures, are usually repaired by patches, strips, or new backs. Various shades in the color of the ink may be the result of time only in old papers, or they may indicate the reaction of chemical agents in efforts to remove it. Irregularity in the written lines and roughness may be consequent upon a bad quality of paper, or be caused by washing the sizing out of the paper in an effort to remove the ink. Washing, also, may cause an apparent irregularity in the thickness of the paper, leaving spots, from which the sizing has been removed, more or less transparent and rough, and thus simulate or obscure other spots which have been erased. All writing paper, in the process of its preparation, is sized; that is to say, it has incorporated with it substances which hinder the penetration of ink or other fluids. When, therefore, the ink strokes are large, or spread into the texture of the paper, they indicate the tamperings of forgery. Where resin has been used for smoothing over an erased surface, the contrary effect results; the ink is but sparingly absorbed by the resin, the lines are fine and superficial, and of glossy appearance. Blots, too, may be the result of original composition in consequence of poor paper, of accidental moisture, of age, smoke, or scorching; it is important, therefore, to determine these conditions. In general, blots which are the result of badly sized paper, or of washing, are of circular shape, and present a regular fa ling shade of color from center to circumference. Blots, of brownish color and glossy, are usually produced by bistre or liquid-brown, and are indelible. Humidity, or moisture, which is liable to occur in papers not well cared for, or by accident, is equally liable to occur in any or every part of the paper. The destructive effects of humidity are sometimes counterfeited by the application of acetic or other strong acids, which more effectually destroy the ink by a partial or total destruction of the paper in the places to which the application is made; whereas mere moisture scarcely or not at all affects the texture of the paper, otherwise than by removing the sizing. Besides, the acids are usually applied in particular places-the usual temptation being to partially and not wholly destroy the papers subjected to this means of counterfeiting.

For the restoration of ink traces which have been made to disappear through the influence of moisture, heat is an available and reliable agent. A good way of applying heat for this purpose consists in placing the sheet to be examined between two sheets of tissue paper and subjecting the whole to pressure between two smooth surfaces of moderately heated iron. A still more effectual method, but requiring more care, is first to wet the papers separately in alcohol, then carefully place them as above, and apply the heated plates. A simpler, but more hazardous, plan, is to scorch the defaced document before a hot fire. Any of these measures, carefully applied, will ordinarily restore legibility to written instruments which have suffered no other damage than mere moisture. But if acetic or other strong acids have been applied, it is almost needless to state, the writing will not be restored, since their use involved a destruction of the paper, as well as the ink, in the places to which they have been applied.

II. CHEMICAL EXAMINATION.-First on the list of the means applicable under this head, may be placed distilled water. By it we can easily discover whether erasures have been made and partially resized, or whether the paper has been rubbed with resin. For the performance of this experiment, the paper to be examined should be smoothly spread out on glass, the water added a little at a time, and carefully observed in its effects on the paper. If the sizing has been removed by erasure or washing, the spots will be indicated by the greater readiness with which they absorb the water; while if any places have been rubbed with resin these wholly fail to absorb water, and thus become equally manifest.

M. Chevalier (Dictionnaire des Alterations et Falsifications,) relates cases where not only forged words have been substituted, but the kind of pen indicated by the impression made in writing. In one such case the point of a metalic pen with a divided beak had been used, and pressed so hard as to scratch two lines in the formation of the letters; these lines were traceable by the ready absorption of the water, which was not the case in the genuine part of the instrument. And in another case a semi-transparent spot was discovered to have been written over with a stylet, as if for the purpose of avoiding the accident which led to the discovery made in the case related; and, in this latter case, the smooth single point of the stylet had the effect of so condensing the erased paper as to render the forgery manifest from a totally opposite effect, namely, the non-absorption of water in the line of writing, while the parts immediately contiguous absorbed moisture with great facility.

By distilled water we can also determine the nature of blots, or of blanks whether they have been caused by the use of acid or alkaline substances, for the diffusion or for the removal of the ink. For this object the water should be applied in drops to the suspected places, and allowed to remain ten or fifteen minutes, and then removed by means of a pipette, and subjected to the usual chemical tests for acids and alkalies. To render this test more certain, the genuine portion of the writing should also be wet with the distilled water, for the purpose of discovering the acid or alkaline nature of the ink used in the original composition. For, if an acid ink has been used upon a paper containing a carbonatesuch as the carbonate of lime or chalk, which is frequently used in the dressing of paper-the acid of the ink acts upon the carbonate and forms, with it and the iron contained in the ink, a ferruginous salt. This salt, becoming dissolved by the application of the distilled water, partially

destroys the sizing of the paper, and causes the ink lines to appear semitransparent. In the use of water for these purposes, it is necessary to repeat the experiment many times. After having moistened and examined the paper for one purpose, allow it to dry, and repeat the experiment for another.

Alcohol.-In some cases where water has failed to satisfy the mind of the scientific inquirer in regard to the suspected use of resin in combination with other substances, for the purpose of obliterating erasures, the use of alcohol has solved the problem by dissolving the resin, after which the experiments with water inay be repeated and verification rendered complete. Paper moistened with alcohol for this purpose may also be subjected to a pretty good test by being placed between the eye and the light. If semi-transparent spots appear in the written lines they are probably owing to erasures; and if, upon drying, the ink is found to be feebly impressed or blurred in these places, evidence of forgery may be considered complete. And it may here be remarked that those lawyers who use pounce, if there are any such, are liable thereby to destroy their own evidence of authenticity. It is somewhere recorded of Stephen Girard that a well recommended book-keeper once sought employment of him, and among other good qualities the applicant was specially commended for his extreme neatness in making erasures, and so filling them as to leave no indications of their existence. After proving his expertness in this particular, and confidently addressing himself to the great merchant, as if sure of the place he sought, he received for reply, If I know it, I never employ anybody who uses pounce."

Test Papers.-These are best prepared from litmus, a peculiar coloring matter obtained from Roccella tinctoria-Spanish orchilla-a small dry lichen, chiefly obtained from the west coast of Africa and neighboring islands. A strong solution of litmus, fit for dying test paper, may be made by triturating one part of litmus with six parts (by weight) of water, gradually added, and then boiling the mixture for half an hour. Unsized white paper, dipped in this solution, immediately acquires a deep purple color. And thus prepared, it should be carefully dried and kept in well closed vessels, secluded from light, ready for use. If moistened with an acid, this purple paper is immediately changed to red; if moistened with an alkali it is changed to blue. Some strips may be preserved in a reddened state by moistening the purple paper in a weak solution of acetic acid, and these, when applied to an alkaline solution, are immediately restored to their original purple color or changed to a blue-depending upon the strength of the alkali. In testing for acidity, it is useful to expose the purple paper for a few seconds to the vapor of ammonia just before applying it; this has the effect of intensifying the blueness, and rendering it more sensitive to the presence of an acid.

Ordinarily, test papers are preserved in narrow slips, but for the examination of written instruments or bank notes suspected of forgery, it is necessary to have whole sheets of test paper, or at least sheets as large as the papers to be examined; and the manner of using them is this:Take a sheet of the purple test paper of the same size as the suspected document, moisten it with distilled water, and carefully spread it out on a sheet of white tissue paper; then lay upon it the paper to be examined, the test paper being between the tissue paper and the suspected document. Thus arranged, put the whole together between plates of glass, and subject them to pressure for about an hour; by the end of this

time the test sheet on removal will be found to vary in shades of color according to the preponderance of acids or alkalies with which it has been in contact, and thus will be indicated whether the ink of the suspected instrument has been subjected to manipulations for the purpose of removal. The presence of acids or alkalies having been thus ascertained, the document may then be submitted to a further examination by dissolving out the agent used, in the manner before directed—by adding distilled water in drops, and subsequent removal by the pipette; and the identity of the substance established by chemical analysis. In the performance of this experiment, it frequently turns out that, in consequence of the presence of acids used in the manufacture of the paper, there is a uniform change of color in the test. This, however, being uniform, is no detriment to the value of the test, because of the increased potency of additional acids which may have been used, the test is correspondingly affected.

There are other valuable tests depending upon the well known qualities of ink. Ordinarily, ink is a metallic preparation, having for a basis a compound formed by the action of nutgalls on the oxide of iron. This compound chemically consists of the tannate of the protoxide of iron, and this substance, after a time, attains its maximum degree of oxidation, and takes on the brilliant black color peculiar to well-made ink. To increase this brilliancy, mucillage, gum, or sugar is sometimes added; and for given shades of color, indigo, logwood, or sulphate of copper; but the tannate of the protoxide of iron is the essential quality of good ink. The counterfeiter, being aware of this, seeks to abrogate the ink by such means as are least liable to detection, and which will incur the least likelihood of notice to his subsequent manipulations. Foremost among these means are certain strengths of the strong acids-muriatic, acetic, and oxalic, and chlorine; a chief object being to use these substances in such a state of solution as will effectually remove ink without affecting the texture of the paper. The difficulty of accomplishing these purposes is made manifest by the certain tests of experimental chemistry. It should be premised, however, that notwithstanding the certain qualities of well-made ink, the acids of nutgalls, which enter into its composition, sometimes take on destructive modifications; this is particularly the case if the ink has been subjected to a freezing temperature. The oxide of iron is then set free, and assumes its natural yellow color. Ink thus spoiled should never be used for drawing up writings of importance, because it continues to fade, even after being committed to paper, and is ultimately destroyed by time alone. This alteration is more or less rapid according to the good or bad preparation of the ink in the first place, and also according to the nature of the modifying substances which have been added to it; it may also be influenced by the quality of the paper upon which it is used.

In the examination of instruments of writing suspected of forgery, we have arrived at the conclusion that the object is three-fold, namely, the detection of the forgery, the detection of the means used, and the restoration of the instrument. These purposes are made apparent by what has gone before. But it now remains to demonstrate the utility of divers substances useful for all the purposes herein comprehended. At the head of these stands iodine. The best way of using this is in the form of vapor, which is easily accomplished by putting a few grains of the metal into a wide-mouthed vial, and subjecting it to a moderate heat. Iodine soon

evaporates on exposure to heat, and the paper to be tested by it can be so held as to allow the vapor of the iodine to impinge upon its surface. After this the paper may be left for three or four minutes, and then carefully examined. If the surface of the paper has not been touched or operated upon by any other substance, the iodine imparts a uniform yellowish or yellow-brown color, on every part of the surface exposed to its influence. If any liquid-water, alcoliol, salt water, vinegar, saliva, tears, urine, acids, or alkalies-has been applied to the surface of the paper before its exposure to the vapor of iodine, the places to which such application has been made are indicated by the varying tints of color imparted by the iodine. Places which have been rubbed with pumice are indicated by a bistre-brown color, and those transparancies which have been repaired by the use of paste are of a bluish-violet tint; while all spots in the paper, from which the sizing has been removed in consequence of washing, wetting with alcohol, or the use of acids, show their places by the more or less varying shades, depending upon the nature of the substance used, and the effect it may have had on the texture of the paper. The place of forgery being thus indicated by the iodine, it may afterwards be treated with the appropriate chemical tests for ascertaining the exact nature of the substance used. Photographs subjected to iodine vapor, and subsequently treated by a solution of the cyanide of potassium, are completely destroyed.

Forgery, by means of chlorine and its preparations, may be detected by nitrate of silver. For this purpose, first dissolve out the substance used, and add to it a solution of nitrate of silver; if chlorine be present in any form, there will be a dense white precipitate of the chloride of

silver.

Gallic acid, or the recently prepared tincture of nutgalls, sulphuretted hydrogen, ammonia, and the alkaline sulphates, are all useful agents for restoring the traces of ink which have been deprived of their color by chlorine or other substances. For this purpose, the paper to be operated upon should be carefully spread out on a smooth surface, and gradually moistened by the reactive, and its changes watched for. When the surface has been well moistened with one test, it should be allowed to dry, and it may be of benefit to let several days, or even weeks, intervene, before another is used. If no traces of ink appear, another may be tried, and so on, the process being repeated many times. Traces of ink have sometimes appeared in paper so treated, at long intervals subsequent to the experiment-evidently traceable to the influence of these agents.

Next to the knowledge necessary for the detection of forgery, it is important to know by what means forgery may be rendered more difficult, and less liable to be attempted in the outset. As long ago as 1825, the Ministers of Justice in France consulted the Academy of Sciences upon the best means for the prevention of numerous disasters, both public and private, consequent upon forgery. The commission charged with the examination of the subject, proposed two methods-1st. The employment of indelible ink. 2d. Stamped paper.

1. Indelible Ink. This name is only appropriate to those inks which are known to be easily taken up by prepared paper, and unalterable under the influence of prolonged washings, chlorine, acids, and alkalies. A great variety of samples purporting to answer these qualities were