. Discovery. Science. DISCOVERY 317 Ink Pigments in Writing By C. Ainsworth Mitchell, , Police reports abundantly prove that the crime of forgery frequently engages the attention of our magis- trates. This is not surprising if we remember that the means are in the hands of all who can write, and that bankers' cheques are a common medium of exchange. The evidence usually demanded by the prosecution is that of the handwriting expert, who bases his opinion on the form and peculiarity of the writing ; but there is evidence of another kind, less known to the public, namely the chemical e
. Discovery. Science. DISCOVERY 317 Ink Pigments in Writing By C. Ainsworth Mitchell, , Police reports abundantly prove that the crime of forgery frequently engages the attention of our magis- trates. This is not surprising if we remember that the means are in the hands of all who can write, and that bankers' cheques are a common medium of exchange. The evidence usually demanded by the prosecution is that of the handwriting expert, who bases his opinion on the form and peculiarity of the writing ; but there is evidence of another kind, less known to the public, namely the chemical examination of the ink or pencil marks on the documents, which is often not only more trustworthy but actually throws more light upon the mvstery. Suppose, for example, additional letters have been added to a cheque, it is comparatively easy by chemical means to ascertain whether or not the inter- polated characters have been written with the ink used for the body of the document. There are other methods, of course, which are useful in deciding on the genuineness of documents, photography for example, but in this article we shall confine ourselves to describing what is known about, and what can be learned from, the ink pigments which are used in writing, partly as matters of interest, and partly in their relation to the genuineness of documents. For this purpose some characteristics of ink must nrst be described. The principal kinds of inks employed at the present time are known as carbon ink, iron-gall ink. and aniline ink. There are others, but these are the principal three. The ink in common use in this coun- try, the famOiar " blue-black," is a mixture of iron-gall ink and a blue aniline ink ; it is best to discuss it, therefore, after its constituents have been described. Carbon ink is not generally used for writing purposes in this country. Such inks are used in Europe only in the form of Indian ink or " safety " inks, to which lampblack, which is the b
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