VOL. LXXVII.] PHILOSOPHICAL TRANSACTIONS. 351 



the plates, to form their external lamellae j dd, the part analogous to the gum j e, a fleshy sub- 

 stance, covering the jaw-bone, and on which the inner lamella of the plate is formed j f, the ter- 

 mination of the plate of whalebone in a kind of hair. 



Fig. 9j a perpendicular section of several plates of whalebone in their natural situation in the 

 gum } their inner edges, or shortest terminations, are removed, and the cut edges of the plates seen 

 from the inside of the mouth. The upper part shows the rough surface formed by the hairy termi- 

 nation of each plate of whalebone. The middle part shows the distance the plates of whalebone 

 are from each other. The lower part shows the white substance in which they grow, and also the 

 basis on which they stand. 



Fig. 1 0, an outline considerably magnified, to show the mode of growth of the plates, and of the 

 white intermediate substance, a, the middle layer of the plate, which is formed on a pulp or cone 

 that passes up in the centre of the plate. The termination of this layer forms the hair } b, one of 

 the outer layers, which grows, or is formed, from the intermediate white substance, cccc, the in- 

 termediate white substance, laminae of which are continued along the middle layer, and form the 

 substance of the plate of whalebone ; d, the outline of another plate of whalebone j e, the basis 

 on which the plates are formed, which adheres to the jaw-bone. 



XXXIX. Some Observations on Ancient Inks, with the Proposal of a New Me- 

 thod of Recovering the Legibility of Decayed Writings. By Charles Blag- 

 den, M. D., Sec. R. S. and F. A. S. p. 45 1 . 



In a conversation some time ago with Thomas Astle, Esq., relative to the 

 legibility of ancient mss. a question arose, whether the inks in use 8 or 10 cen- 

 turies ago, and which are often found to have preserved their colour remarkably 

 well, were made of different materials from those employed in later times, of 

 which many are already become so pale as scarcely to be read. With a view to 

 the decision of this question, Mr. Astle obligingly furnished several mss. on 

 parchment and vellum, from the 9th to the 15th centuries inclusively; some of 

 which were still very black, and others of different shades of colour, from a deep 

 yellowish brown to a very pale yellow, in some parts so faint as to be scarcely 

 visible. On all of these I made experiments with the chemical re-agents which 

 appeared best adapted to the purpose ; namely, alkalis both simple and phlogis- 

 ticated, the mineral acids, and infusion of galls. 



It would be tedious and superfluous to enter into a detail of the particular ex- 

 periments ; as all of them, one instance only excepted, agreed in the general 

 result, to show, that the ink employed anciently, as far as the above-mentioned 

 MSS. extended, was of the same nature as the present : for the letters turned of 

 a reddish or yellowish brown with alkalis, became pale, and were at length ob- 

 literated, with the dilute mineral acids, and the drop of acid liquor which had 

 extracted a letter, changed to a deep blue or green on the addition of a drop of 

 phlogisticated alkali ; the letters also acquired a deeper tinge with the infusion of 

 galls, in some cases more, in others less. Hence it is evident that one of the 

 ingredients was iron, which there is no reason to doubt was joined with the 

 vitriolic acid ; and the colour of the more perfect mss. which in some was a deep 



