Ink applied to the surface of paper from which the sizing has been removed will show more or less tendency to spread, as upon blotting paper, and although this may be so slight as to escape the notice of the naked eye, it will be plainly visible under the microscope, and on a photographic enlargement the rough edges of the marks will be very pronounced. Every little fault or attempt at touching up will be brought into prominence, and in cases where writing has been removed by the use of chemical reagents the slight yellow stain which is frequently formed upon the paper--a stain so trifling that it would not ordinarily attract notice--will appear as a dark blotch upon a photographic reproduction. It has frequently been claimed that it is possible to distinguish between different kinds of ink by means of photography. Since inks contain provisional colouring matters which cause the dried pigment upon the paper while apparently black to be in reality red-black, blue-black, etc., it was asserted that such differences would be made manifest in photographs taken on an ordinary plate, and still more by the use of colour-sensitive plates. The present writer, however, has been unable to confirm these statements. It is true that differences in intensity appear upon the negative, but these are not any more pronounced than the differences obvious to the eye in the writing, and the use of special plates and screens does not give any more satisfactory results. The chief use of the photographic methods is to distinguish differences in form rather than in colour, and to record them for purposes of demonstration. One direction in which photography is particularly useful is in deciphering the words in faded ink upon old documents, for the yellow colour of the ancient vellum is due to the formation of iron oxide. Of recent years photography has supplied another valuable means of detecting alterations in documents, and it has been found particularly useful for demonstrating to a judge and jury the results of a microscopical examination. Photographic reproduction and enlargement has the advantage over chemical methods of not producing any alteration in the ink or paper, and in some instances is just as effective as the latter. In the examination of wills, for instance, it is necessary to obtain the express permission of the President of the Probate Court, before any chemical tests may be applied to the document, and except under special circumstances such permission would certainly be refused.