The general dissatisfaction with the behaviour of the Bank authorities was intensified by the amount of public money that was spent in the prosecution of the forgers, and the view was freely expressed that the Bank had no right to assume the office of prosecutor. In the year 1818, for instance, there were 242 prosecutions, the cost of which was £34,357. So pronounced became public opinion upon the subject that the Bank was forced to allow the culprits to plead guilty to a minor charge, the penalty for which was transportation instead of death. This became almost a necessity, since there were frequently batches of twenty or thirty convicted forgers awaiting execution, though the death penalty was only exacted in a relatively small proportion of the cases. During the seven years ending 1825 there were 78,918 males and 14,800 females tried on the charge of forging these notes. Of these prisoners, 17,874 were acquitted, while out of the remaining 75,844 sentence of death was passed upon 7,770, though not more than 579 of these were executed. Even this small proportion gave the terrible yearly average of eighty-three executions. As it was at that time impossible to stop these wholesale forgeries the abolition of the issue of one pound notes, which took place in 1826, was obviously the only solution of the difficulty. CHAPTER VIII DISTINGUISHING INKS IN HANDRWRITING Elizabethan Ink--Milton's Bible--Age of Inks--Carbon Inks--Herculaneum MSS.--Forgery of Ancient Documents. In order to make clear the principles upon which are based the methods of distinguishing between different kinds of ink in handwriting it is necessary to give some account of the nature of ink. Ordinary writing ink is essentially a mixture of a decoction of galls (or other substances containing tannin) with a solution of copperas, or as it is now termed, ferrous sulphate. These substances combine with one another to form a tannate of iron, which gradually changes on exposure to the air into another iron tannate, which is insoluble and constitutes the black pigment of writing. Characters written with a pure freshly-prepared iron gall ink are very faint in colour when first applied to the paper, and it is only after the air has acted upon them that they gradually become dark blue and finally black. In the old type of iron-gall ink, that which was universally employed down to the early part of last century, inks were exposed to the air or were boiled in order that the insoluble black pigment might form within the liquid, and thus give some colour to the ink when it was first put upon paper. The objection to this is that ink thus prepared is liable to clog the pen and not to penetrate properly into the fibres of the paper.