352 PHILOSOPHICAL TRANSACTIONS. [aNNO 1787. 



black, and in others a purplish black, together with the restitution of that 

 colour, in those which had lost it, by the infusion of galls, sufficiently proved 

 that another of the ingredients was astringent matter, which from history ap- 

 pears to have been that of galls. No trace of a black pigment of any sort was 

 discovered, the drop of acid, which had completely extracted a letter, appearing 

 of a uniform pale ferruginous colour, without an atom of black powder, or other 

 extraneous matter, floating in it. 



As to the greater durability of the more ancient inks, it seemed, from what 

 occurred in these experiments, to depend very much on a better preparation of 

 the material on which the writing was made, namely, the parchment or vellum ; 

 the blackest letters being generally those which had sunk into it the deepest. 

 Some degree of effervescence was commonly to be perceived when the acids 

 came in contact with the surface of these old vellums. I was led however to 

 suspect that the ancient inks contained a rather less proportion of iron than the 

 more modern ; for in general the tinge of colour, produced by the phlogisticated 

 alkali in the acid laid on them, seemed less deep ; which however might depend 

 in part on the length of time they had been kept : and perhaps more gum was 

 used in them, or possibly they were washed over with some kind of varnish, 

 though not such as gave any gloss. 



One of the specimens sent by Mr. Astle proved very different from the rest. 

 It was said to be a ms. of the 15th century ; and the letters were those of a full 

 engrossing hand, angular, without any fine strokes, broad, and very black. On 

 this none of the above-mentioned re-agents produced any considerable effect ; 

 most of them rather seemed to make the letters blacker, probably by cleaning 

 the surface ; and the acids, after having been rubbed strongly on the letters, 

 did not strike any deeper tinge with the phlogisticated alkali. Nothing had a 

 sensible effect toward obliterating these letters but what took off part of the sur- 

 face of the vellum ; when small rolls, as of a dirty matter, were to be perceived. 

 It is therefore unquestionable, that no iron was used in this ink ; and from its 

 resistance to the chemical solvents, as well as a certain clotted appearance in the 

 letters when examined closely, and in some places a slight degree of gloss, I 

 have little doubt but they were formed with a composition of a black sooty or 

 carbonaceous powder and oil, probably something like our present printer's ink, 

 and am not without suspicion that they were actually printed.* 



While I was considering of the experiments to be made, in order to ascertain 

 the composition of ancient inks, it occurred, that perhaps one of the best me- 

 thods of restoring legibility to decayed writing might be, to join phlogisticated 

 alkali with the remaining calx of iron ; because, as the quantity of precipitate 



* A subsequent examination of a larger portion of this supposed ms. has shown that it is really 

 part of a very ancient printed book. — Orig. 



