228 Scientific Intelligence.— Geology. 



vatetl point of the Cordillera of Chili, is placed 1° 41' to the 

 east of Valparaiso, and that its latitude is 32° 38'. The angle 

 of height of this peak, measured by the theodolite, is 1° 55' 58" ; 

 from which Mr Pentland deduces 7300 metres as the absolute 

 height of Aconcagua above the level of the sea. The observa- 

 tions of Captains Beechey and Fitzroy, assigned a height of 

 sixty metres less than the result now given. These determina- 

 tious tend still farther to lower the rank formerly held by Chim- 

 berazo. The following is a comparative view of three other 

 heights with that of Aconcagua : — 



Himalayab . . 7S21 metres 



Nevado de Sorata (Upper Teru), . . . 7696 ... 



Aconcagua (Chili), 7300 ... 



Chimberazo (Peru), ..... 6530 ... 



MINEKALOGV. 



13. On Intermediate Chemical Combinations ivhich have not yet 

 been detected by chemists. — ]\I. Biot has very lately read a paper, 

 one of the objects of which is to prove, that, besides the definite 

 and limited combinations between bodies recognised by chemists, 

 there are other intermediate combinations which they cannot de- 

 tect, and whose existence is revealed by optical processes. It is 

 thus that the continual and successive changes which polarized 

 light suffers in passing through a solution of tartaric acid in 

 water indicate, at each addition of water, states of combination 

 at present unknown to chemistry ; and further, it is thus that 

 sulphuric acid and soda, of which only two degrees of combina- 

 tion are admitted, very probably produce a multitude of other 

 intermediate conibinations. 



14. Tantalatc of Iron and ()f Manganese. — M. Desplaces has 

 discovered at Charmasse, near Autun, some specimens of the 

 tantalate of iron and of manganese. This mineral occurs in the 

 quartz which contain beryls, garnet, &c. ; is found in small black 

 masses; has a mttalloidal aspect; and a fracture somewhat 

 lamellar. 



15. Artificial Rubies. — M. Gaudin, as stated in the Coraptes 

 Rendus, August 1837, has lately announced to the French Aca- 

 demy of Sciences, that he has been able, by the following pro- 

 cess, to make rubies, having the characters of the precious ruby. 

 In order to obtain these artificial rubies, M. Gaudin uses a pla- 



