i26 Dr. Daubeny on the occurrence of 



same, when treated with sulphuric acid without having un- 

 dergone such a preparation. 



In proof of this I submit to the inspection of members 

 specimens No. 3 and No. 4 ; the one showing the glass cor- 

 roded by a Kirkdale bone deprived of its animal matter and 

 carbonic acid ; the latter, by one retaining both. Operating 

 in this manner, I have succeeded in engraving upon glass, 

 not only by means of fossil bones, from Stonesfield, from 

 Montmartre, from the cave of Kirkdale in Yorkshire, and 

 from that of Gailenreuth in Franconia, specimens of all 

 which were supplied me by Dr. Buckland ; but likewise with 

 the bone of some quadruped that had been lying for a long, 

 but unknown time, exposed to the weather in the soil of our 

 Botanic Garden ; with the vertebra of an ox recently killed ; 

 with the tibia of a human subject from an anatomical cabinet 

 at Oxford ; with the teeth of an ox just killed, and with human 

 teeth of recent date. The markings differ widely in the de- 

 gree of their distinctness, and are in some instances so faint 

 as hardly to be discerned except by daylight ; but I have 

 convinced myself that they cannot be attributed to the disen- 

 gagement of phosphoric acid, as the same glass was in no de- 

 gree affected by the fumes proceeding from the action of sul- 

 phuric acid upon pure phosphate of lime, where the acid had 

 been derived from the direct combustion of phosphorus, nor, 

 for a long time at least, by the vapour of free phosphoric acid 

 exposed to a heat sufficiently great to fuse and partially to 

 volatilize it. 



Nor was it dependent on any peculiarity in the nature of 

 the glass, for plate glass was corroded in the same manner as 

 the ci'own glass more usually employed. 



By the oldest and most fossilized specimens the glass seemed 

 undoubtedly to be most deeply etched ; yet even here there 

 occurred exceptions, for the marks caused by a bear's bone 

 taken from Gailenreuth are the faintest in the whole series, 

 and were produced only after a long exposure to the acid va- 

 pours, two previous trials having proved unsuccessful ; whilst, 

 on the other hand, the tibia of a human subject gave indica- 

 tions almost as distinct as any even of the fossil bones ope- 

 rated upon. 



It would doubtless have been more satisfactory if I could 

 have stated the proportion of fluorine in these samples of bones 

 and teeth, as well as the fact of its actual presence, and like- 

 wise if I had extended my examination over a larger number 

 of specimens; but I have been compelled to postpone the 

 former part of the inquiry until 1 could obtain an apparatus 

 suitable for the purpose, and doubted when my time would 



