in use in nearly every bank in Europe and the result of his work and

his recommendations should be carefully read and the system applied by

the banks and business houses of the United States, when occasion

requires.



The following article has been specially prepared for this work; and

if its recommendations are carefully carried out it will prove a sure

rule for the detection of forged and fraudulent handwriting:



"Although my experiments were not always carried on under the most

favorable circumstances, their results were eminently satisfactory and

will prove a boon to the banking and business world. A piece of paper

was handed to me for the purpose of determining if part of it had been

wet and if another part of it had been manipulated for the purpose of

erasing marks upon it; in other words, whether this part had been

rubbed. The sample I had to work upon had already gone through several

experiments. I had remarked that the tint of the paper exposed to the

vapor of iodine differs from that which this same paper assumes when

it has been wet first and dried afterwards. In addition to this I

realized that when sized and calendered paper, first partially wet and

then dried, is subjected to the action of iodine vapor, the parts

which have been wet take on a violet tint, while those which had not

been moistened became either discolored or brown. The intensity of the

coloration naturally varied according to the length of time for which

the paper was exposed to the iodine.



"There is a very striking difference also when the water is sprinkled

on the paper and the drops are left to dry off by themselves in order

not to alter the surface of the paper.



"Thorough wetting of the paper will cause the sprinkled spots to turn

a heavy violet-blue color when exposed to vapor while the parts which

are untouched by the water will become blue.



"If, after sprinkling upon a piece of paper and evaporating the drops

thereon, this piece of paper is thoroughly wet, then dried and

subjected to the action of iodine, the traces of the first drops will

remain distinguishable whether the paper is dry or not. In the latter

case the trace of the first sprinkling will hardly be distinguishable

so long as the moisture is not entirely got rid of; but as soon as

complete dryness is effected their outlines, although very faint, will

show plainly on the darker ground surrounding the spot covered by the

first drop.



"In this reaction, water plays virtually the part of a sympathetic

fluid, and tracing the characters with water on sized and calendered

paper, the writing will show perfectly plain when the paper is dried

and exposed to action of iodine vapor. The brownish violet shade on a

yellowish ground will evolve to a dark blue on a light blue ground

after wetting. These characters disappear immediately under the action

of sulphurous acid, but will reappear after the first discoloration

provided the paper has not been wet and the discoloration has been

effected by the use of sulphurous acid gas.



"The process, therefore, affords means for tracing characters which

become legible and can be caused to disappear, but at will to reappear

again, or which can be used for one time only and be canceled forever

afterwards.



"The usual method of verifying whether paper has been rubbed is to

examine it as to its transparency. If the erasure has been so great as

to remove a considerable portion of the paper, the erased surface is

of greater translucency; but if the erasure has been effected with

great care, examining same close to a light will disclose it; the

erased part being duller than the surrounding surface because of the

partial upheaval of the fibers.



"If an erasure is effected by means of bread crumbs instead of India

rubber, and care is taken to erase in one direction the change escapes

notice; and it is generally impossible to detect it, should the paper

thus handled be written upon again.



"Iodine vapors, however, show all traces of these manipulations very

plainly giving their location with perfect certainty. The erased

surfaces assume a yellow brown or brownish tint. If, after being

subjected to the action of the iodine, the paper on which an erasure

has been made is wet, it becomes of a blue color the intensity of

which is commensurate with the length of time to which it has been

under the action of the iodine, and when the paper is again dried the

erased portions are more or less darker than the remainder of the

sheet. On the other hand when the erasure has been so rough as to take

off an important part of the material exposure to iodine, wetting, and

drying result in less intensity to coloration on the parts erased,

because the erasing in its mechanical action of carrying off parts of

the paper removes also parts of the substance which in combination

with iodine give birth to the blue tint. Consequently the action of

the iodine differs according to the extent of the erasure.



"When paper is partially erased and wet, as when letters are copied,

the same result although not so striking follows upon exposing it to

the iodine vapor after letting it dry thoroughly.



"Iodine affords in certain cases the means of detecting the nature of

the substance used for erasing. Bread crumbs or India rubber turn

yellow or brownish yellow tints and these are distinguished by more

intense coloration; erasure by means of bread crumbs causing the paper

to take a violet shade of great uniformity. These peculiarities are

due to the upheaval of the fibers caused by rubbing. In fact this

upheaval creates a larger absorbing surface and consequently a larger

proportion of iodine can cover the rubbed parts than it would if there

had been no friction.



"When paper upon which writing has been traced with a glass rod, the

tip of which is perfectly round and smooth, is exposed to iodine

vapor, the characters appear brown on yellow ground which wetting

turns to blue. This change also occurs when the paper written upon has

been run through a super-calender. If the paper is not wet the

characters can be made to appear or be blotted by the successive

action of sulphurous and iodine vapor.



"Writing done by means of glass tips instead of pens will show very

little, especially when traced between the lines written in ink. The

reaction, however, is of such sensitiveness that where characters have

been traced on a piece of paper under others they appear very plainly,

although physical examination would fail to reveal their existence,

but a somewhat lengthy exposure to iodine vapors will suffice to show

them.



"If the wrong side of the paper is exposed to the iodine vapor the

characters are visible; but of course in their inverted position.



"If the erasure has been so great as to take off a part of the

substance of the paper the reconstruction of the writing, so as to

make it legible, may be regarded as impossible. But in this case

subjecting the reverse side of the paper to the influence of the

iodine will bring out the reverse outlines of the blotted-out

characters so plainly that they can be read, especially if the paper

is placed before a mirror. In some instances, when pencil writing has

been strong enough, its traces can be reproduced in a letter press by

wetting a sheet of sized and calendered paper in the usual way that

press copies are taken, placing it on paper saturated with iodine and

putting the two sheets in a letter book under the press, copies being

run off as is usual in copying letters. The operation, however, must

be very rapidly carried out to be successful. As a matter of fact the

certainty of these reactions depends entirely upon the class of paper

used. Paper slightly sized or poorly calendered will not show them.



"Another point consists in knowing how long paper will contain these

reactive properties. In my own experience the fact has been

demonstrated that irregular wetting and rubbing three months old can

be plainly shown after this lapse of time. Characters traced with

glass rod tips could be made conspicuous. I have noticed that

immersing the written paper in a water bath for three to six hours

will secure better reactions, but although these reactions are very

characteristic they are considerably weaker."