Natural History — Mineralogij — Geology. 191 



presence of lime, and muriate of baryta of sulphuric acid. Hence it ap- 

 pears that the native peroxide of manganese usually contains a small ad- 

 mixture of the muriate and sulphate of lime. 



18. Analysis of the Meteoric Stone tuhich fell near Ferrara in 1824.. — 

 Mr Laugier found the stone to be thus composed : 



Peroxide of Iron, - - 43 



Silex, • - - 41.75 



Magnesia, - - 16. 



Oxide of Chrome, . - 1.50r 



Oxide of Nickel, - - 1.25 



Sulphur, - - 1. 



104.5 

 The quantity of sulphur and nickel is less in this than in other meteo- 

 rites. — Ann. de Chim. Feb. 1827, tom. xxxiv. p. 141. , 



III. NATURAL HISTOKY. 



MINERALOGY. 



19. Crystallized Fyrope. — In the Iser mountains in Bohemia, crystals of 

 this species have lately been discovered by a pupil of Professor Zippe of 

 Prague. In this new locality pyrope generally also is found in grains, but 

 many of them exhibit traces of a crystalline surface, and one individual in 

 particular showed the perfect form of a hexahedron, the length of its sides 

 being about a line, with faces slightly curved, as is often the case in dia- 

 monds. Professor Zippe described it in a particular memoir, which was 

 read before the Society of the National Museum of Prague. He esta- 

 blishes it there as a species of its own, belonging to the genus garnet of 

 IMohs, under the name of hexahedral garnet. 



20. Remarkable optical propei^ty of Dichroite. — Professor Marx of Bruns- 

 wick discovered that dichroite, cut parallel to the crystallographic axis of 

 the crystals, has the property of polarizing light exactly in the same man- 

 ner as tourmaline. This substance, therefore, promises to become highly 

 valuable to those who occupy themselves with the optical examination of 

 minerals, since it is not uncommonly found of a uniform texture and co- 

 lour, and considerable degrees of transparency. The mineral has the pro- 

 perty of polarizing light also when cut perpendicular to the axis, as might 

 have been anticipated from the circumstance of its having two axes of 

 double refraction. — rSchweigger's Journal, vol. xvii. p. 368.) 



GEOLOGY. 



21. Dr Hibbert's System of Geology. — Dr Hibbert is in considerable 

 forwardness with the system of Geology which he has many years been 

 preparing for publication. It is intended to contain a succinct view of 

 the History of the Earth, with a geological arrangement of the various 

 mineral substances which each description of rock contains, and a par- 

 ticular account of the organic remains which have beeti disoofvered in thfe 



