Scientific Intelligence — Geologi/. 213 



5. Fossil-Tree at Granton, near Edinburgh. — A great fossil- 

 tree, similar to that at Craigleith, has been discovered in the 

 sandstone quarry at Granton. Its dimensions cannot yet be 

 ascertained, but the distance between the extreme points al- 

 ready uncovered is about forty-five feet, and its breadth, 

 where most exposed, is about three feet. 



6. Method of distinguishing Trap from Basalt. — Mons. A. 

 Braconnot finds, that these rocks may be distinguished by 

 subjecting them to distillation ; the trap always yields an 

 empyreumatic product, which restores the colour of litmus 

 paper reddened by an acid, whereas basalt produces no such 

 effect ; and he presumes that the organic matter which had 

 existed in the materials of the basalt, Avas destroyed by the 

 volcanic heat by which the rock was produced ; whereas, he 

 conceives trap to have been formed in water, under the in- 

 fluence of a moderate temperature, insufficient to destroy the 

 organic matter which was contained in the debris from which 

 it was formed. The trap was selected from various places, 

 and of an unquestionable nature ; and the basalt was that of 

 Clermont, in Auvergne. M. Braconnot has also found, that 

 various granites yield ammonia when heated, and the same 

 effect was produced by serpentine and porphyry ; but the 

 gneiss of Freiberg, in Saxony, yielded an acid which appeared 

 to be the hydrofluoric. Many other rocks, of various kinds, 

 were subsequently found to yield ammonia. — Ann. de Chim. 

 et de Phi/s., January 1838. 



7. Tornadoes on the West Coast of Africa. — There are 

 squalls within the limits of the trade winds which evidently 

 are not of the nature of rotatory storms. From explanations 

 received from naval offices, as well as from some log-books, I 

 should be convinced that the tornadoes on the west coast of 

 Africa, as well as the pamperos on the coast of South Ame- 

 rica, and also arched squalls, are phenomena altogether dif- 

 ferent from the whirlwind ; but this opinion still requires con- 

 firmation. — lieid on Lan of S'tor/ns. 



