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the sun and open air, the writing changed to a yellowishbrown. The mixtures, in which the vitriol exceededthe galls, underwent greater and speedier changes ; moreand more so, according as the excess of the vitriol wasthe greater. Those in which the galls exceeded thevitriol were more durable: an infusion of two parts ofgalls and one of vitriol did not fade so much in twomonths exposure, as an infusion of equal parts of thetwo did in one month; and three parts of galls to one ofthe vitriol made an ink which held its colour still better.When the galls were increased, to five or six times theweight of the vitriol, the colour did not prove blackenough, though it seemed to be rather of more durabilitythan the others.

The writings which had changed to a brown or yel-low, I washed over with an infusion of galls. Where theink had been well loaded with the ingredients, the cha-racters became of a pretty good black; and those, whichhad been written with more dilute inks, became, thoughnot black, yet sensibly more coloured than before, iftsb-much that many, which had grown almost indistinguish-able, were now sufficiently legible. How far, this infusion-would serve for the recovery of decayed writings of greatage, I have not had an opportunity of trying; but thusmuch is clear, that a distilled water of galls, recommendedfor this purpose in Caneparius’s collection de atramentis,cannot answer the astringency, or the power of givingblackness to iron, residing in such; parts of the galls as donot rife in distillation.

It seems to follow from the above experiments, that thedecay of inks is owing chiefly to a deficiency of galls jthat the galls are the most perishable ingredient, thequantity, which gives the greatest blackness at first, beinginsufficient to maintain the colour; that for a durable

ink,