Natural History. 169 



posited against the sides ; and it occurs in proceeding, until 

 replaced by a black earth, which, in certain places, forms the 

 entire bottom of the cavern, and preserves the form of the blocks 

 of lava, which appear to have fallen from the roof. 



The white earth has a slight tint of yellow, no consistence, 

 and is very light; it feels unctuous, and adheres to the tongue. 

 On analysis, it proved to be a subphosphate of alumina, mixed 

 with a small quantity of phosphate of ammonia. 



1.400 Alumina. 

 0.914 Phosphoric acid. 

 0.094 Ammonia. 

 Water. 



The black matter found in the cavern was almost entirely 

 animal; five parts gave only 0.35 of ashes when burnt, which 

 were phosphate and carbonate of lime, with a little iron. In 

 the same cavern were found heaps of bones, which, from a 

 specimen brought home, appeared very ancient. The specimen 

 was very fragile, and was covered with crystals, in brilliant 

 needles, which proved to be phosphate of lime. M. Vauquelin 

 suggests that this animal matter was the source of the phospho- 

 ric acid, found united with the alumina, 



8. Crystallized Stalactitic Quartz.— The stalactites which 

 covered the roof of this cavern, when examined by M. Vauquelin, 

 proved to be quartz. They were found in concentric layers, and 

 offered all the physical characters of calcareous stalactites, 

 except the hardness. The composition was, 



Silex 850 



Oxide iron . . .060 



Lime 031 



Water 150 



Loss 009 



1.100 

 Jnn. de Chim. xxi. 188. 



9. Ammonia mZav«.— Professor Gmel in, of Tubingen, is said 

 to have discovered, in clink-stone lava, ammonia, which is dis- 

 engaged by distillation. He alsp found it in columnar basalt. 



10. Muriate of Ammonia from Coal Strata.— There is a coal- 

 mine near Saint Etienne, which, having been fired, through in- 



