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Monday, 20th Decemher 1852. 

 Dr CHRISTISON, Vice-President, in the Chair. 



The following Communication was read : — 



On the supposed occurrence of Works of Arts in the Older 

 Deposits. By James Smith, Esq. of Jordanhill. 



The author, after mentioning various cases of this nature, in all 

 of which th« evidence was very defective, exhibited a tool of wrought- 

 iron, said to have been found in the coal, but which was only proved 

 to have come out of a coal-pit. 



He then shewed an Indian arrow-head in a calcareous deposit in 

 situ from Canada, which, at first sight, might he supposed to be 

 coeval with the formation of the deposit ; but on examination, the 

 calcareous mass proved to be quite superficial, so that nothing could 

 be easier than for the arrow-head, which is of the usual Indian form, 

 to have fallen on the wet surface, and to have been thus apparently im- 

 bedded. The author concluded that no evidence had yet been adduced 

 to prove the occurrence of works of art in any of the older deposits. 



Tuesday, Ath January 1853. 

 Dr MACLAGAN in the Chair. 



The following Communications were read : — 



1. On the Optical Phenomena and Crystallization of Tour- 

 maline, Titanium, and Quartz, within Mica, Amethyst, 

 and Topaz. By Sir David Brewster, K.H., D.C.L., 

 F.R.S., and V.P.R.S. Edin. 



1 . The first part was on the distribution of Tourmaline in Mica. — 

 When liquids or gases have been confined in mica, they have often 

 easily escaped and spread between the plates. Crystals, both of 

 tourmaline and quartz, are found in mica, contemporaneous with it, 

 and of considerable size. Such crystals generally have the faces of 

 the hexagonal prism parallel to the laminae of the mica. 



But other crystals of tourmaline formed subsequently, and between 

 the laminge, are very different. They are hexagonal plates, with 

 faces perpendicular to the axis of the prism. Some of the fluid 

 which deposited them has penetrated between the laminae, and there 



