478 



(iitional upheave, — as the considerable dip of the old red sandstone 

 from that chain could not otherwise be very well accounted for. 

 The colour of the old red sandstones he attributed to the wearing 

 down of the greywacke and porphyritic rocks of a red colour. The 

 reason why the outburst of the porphyritic rocks took place before 

 the augitic traps, he supposed might be the smaller specific gravity of 

 the former. 



Mr Stevenson's paper was illustrated by a geological map, as 

 well as by numerous sections. 



3. Notice regarding The Indian Grass Oil, or Oil of Andropo- 

 gon Calamns-aromaticus. By Thomas G. Tilley, Phil. D. 

 Communicated by Dr Christison. 



The oil known as Indian Grass Oil, has been referred by Dr 

 Royle to the Andropogon Calamus-aromaticus, a plant which he con- 

 ceives to be identical with the KaXa/xoj agw^ar/xos of the Greeks. 

 It has been used in medicine as a stimulant embrocation in rheuma- 

 tism, &c. 



The oil, which was green, became yellow when heated. It ac- 

 quired a steady boiling point at 440°, between which temperature 

 and 442°, a transparent colourless oil distil over. This, after recti- 

 fication by chloride of calcium, was analysed, and found to have the 



following composition. 



Found. Atoms. Calculated. 



Carbon 88.10 10 88.46. 



Hydrogen 11.29 16 11.54. 



from which data, it appears that the oil of grass contains, and chiefly 



consists of a caibo-hydrogen, in which the proportion of the carbon 



is to the hydrogen, as 10 to 16, as in the case of oil of turpentine, 



and other volatile oils of the same class. 



The following Donations of Books to the Society's Library 

 were announced : — 



Memoires presentes par divers Savants a I'Academie Royale des 

 Sciences de I'lnstitut de France. Tome viii. — By the Royal 

 Academy. 



Memoires de la Societe de Physique et d'Histoire Naturelle de 

 Geneve. Tome x.. Part 1. — By the Society. 



Annales des Sciences Physiques et Naturelles d' Agriculture et 



