182 Scientific Intelligence, 



iron, magnesia, and alumina. It is found in the volcanic feldspath-rocks, 

 in the neighbourhood of the Lake Laach Sea in Rhein-Prussia. The tau- 

 tolite seems to be related to the chrysolite, as the Ceylanite to the Spinelle. 



27. Mica from New Jersey. — It is tetarto-prismatic, and blackish-green. 

 The angles, in reference to Fig. 32 of Moh's Treatise on Mineralogy, are 

 the following. M on T = 73° 40', P on M = 110°, P on T — 118° 0'. 

 Cleavage parallel to P. — {Vide Kobell, in Kastner's Archiv.fur die gesammte 

 Naturlehre, Vol- x. p. 291. 



28. Dr Thomgon's analysis of Pure Chromate of Iron, — Hitherto the 

 specimens of chromate of iron were mixed with octaedral iron and other 

 extraneous matters. Dr Thomson however succeeded in finding octaedral 

 grains nearly pure. 



Green oxide of chrome 

 Peroxide of iron, - - . 



Alumina, ... 



Silex, .... 



Or when free of all mixture. 



Green oxide of chrome. 



Peroxide of iron, ... 



Alumina, - . . . . 



Ann. des. Mines, 1827, p. 280. 



GEOLOGY. 



29. On the Boulder-stones in the North of Germany. — Professor Haus- 

 mann, in a paper read before the Royal Society of Gottingen, at the meeting 

 of the 25th August 1827, has shown that the numerous fragments of rocks 

 and boulder-stones found in the sand-plains of Northern Germany, and in 

 Denmark, originate from the mountain-formations in Sweden and Norway. 



30. Baron Von Buck on Volcanoes. — Baron Leopold Von Buch had pre- 

 pared in 1 825 a physical description of the Canary Islands. This important 

 work is not yet published, but a notice of a most interesting part of it, a trea- 

 tise " on the nature of the volcanic phenomena in the Canary Islands, and 

 their connection with other volcanoes of the earth," is given, with many new 

 notices, in vol. x. of Poggendorff's Annalen der Physik und Chemie. " Baron 

 Von Buch, one of the most celebrated observers of volcanic phenomena, di- 

 vides all volcanoes into central ai.nA /«nmr(Reihen)volcanoes; the last appear 

 to follow great fissures in the earth, and these again take the direction of the 

 primitive rocks. Under the central volcanos this celebrated geologist ranks 

 those of the Lipari Islands, Etna, the Phlegraean fields, Iceland, the Azo- 

 res Islands, the Canary Islands, the Islands of Cape Verde, the Gallo- 

 pagos. Sandwich, Marquesas, Society, and Friendly Islands, the Island of 

 Bourbon, and many other volcanoes in the interior of several countries. 

 All others are linear volcanoes. 



31. Greenstom and Porphynf qfihe -ffar^*.— Careful observations iu the 



