With the introduction of adhesive labels for denoting the prepayment of postage, it was feared that means would be devised for removing the obliterations, and so enabling the stamps to be used on successive occasions. The One Penny labels, being printed in ordinary black printer’s ink, readily lent themselves in this respect to treatment of the most drastic character ; and, within a few weeks of their issue, communications were received from chemists and others in all parts of the kingdom, calling the attention of the authorities to the fact that the cancellation might be entirely removed from the same stamp for an almost infinite number of times without injury to the impression. The red obliterating ink thus proving worthless as a .security against the fraudulent use of the labels, it became necessary to provide another medium for cancellation, of such a character that no re-agent would act upon it without at the same time affecting the stamp itself.

With this object in view, Mr. Rowland Hill consulted the eminent chemist Faraday, who approved of his suggestion to print the stamps with an aqueous ink, and to obliterate them with an ink of a similar character.

It was decided (25th August, 1840) in the meantime to use ordinary black printing ink for obliterating, and it would appear that this was brought into use forthwith, though several months elapsed before the red cancellation was superseded. The earliest obliteration in black which we have seen is dated the 31st October, 1840.