which possesses, in perfection, the quality that was desired of sinking instantly into the paper, so as to make it far more difficult to discharge it without destroying the texture on which it is written, and of being perfectly secure against water by which Indian and other carbonic Inks are so easily effaced. It is not, however, equally secure against the effects of time; for vitriolic ink gradually, fades away, becomes paler by degrees, turns brown and yellow, and is scarcely legible; and sometimes, as the parchment grows yellow and brown with age, it disappears altogether. A compound kind of ink came next into use, which united the advantages and avoided the defects of the two simple sorts. Such a mixed ink was generally, used for several centuries; and with this, the manuscripts that are now most fresh and legible appear to have been written. It is evident that the ink with which the original marks contained in the Palimpsest manuscripts that have been deciphered were written, was at least in part vitriolic: for the letters which had been rubbed out were rendered legible by the application of the infusion of galls In order to remove the original writing, the parchments on which the mixed ink had been used were, probably, first masked to take off the carbon, and thus partially to efface
