Scientific Intelligence — Geology* 



Kne form of common feld-spar, with the angle M. T. = 120° 15. 



It fuses before the blowpipe with difficulty, and shews in the outer 

 flame an intense soda reaction. Composition, according to M. 

 Plattner, silica 63*50, alumina 20*29, oxide of iron 0*67, potash 

 3-03, soda 876, lime 3-22. water and fluoride of silicon 1-23. It 

 occurs with pyroxene, graphite, and calc-spar. 



11. Native Tin. {Jour of Prackt. Chem, xxxiii., 300). — Ac- 

 cording to Hermann, native tin occurs in the gold washings of the 

 Ural, in small grey metallic grains, containing also some lead. 



12. Aragonite and Calc-spar. {V Institute No. 664, July 

 15, 1846, p. 240). — ^MM. Silbermann and P. A. Favre have ar- 

 rived at the conclusion, that these two minerals are isomeric, and that 

 the dimorphism of carbonate of lime is due to this principle. The 

 arragonite is shewn to be the higher of the isomeric compounds. 



13. On lolite. — In an elaborate memoir on the mineral lolite, 

 including its several varieties, M. Haidinger shews that the so- 

 called mineral species, Finite, Fahlunite, Weissite, Bronsdorffite or 

 Hydrous lolite, Gigantolite, Chlorophyllite, Praseolite, Esmarkite, 

 and perhaps also Oosite, are only metaphors of lolite, arising from a 

 change of composition in crystals of this species.* (American 

 Journal of Science and Arts, Vol. ii., No. 6, 2d series, p. 513.) 

 Also (,Pogg. Annal, 1846, Ixvii., 441). 



GEOLOGY. 



14. Cocoa Trees in Stratified Sand. — It was one o'clock, p.m., 

 when we reached a little village called Pebla, which is situated on 

 the coast, about five leagues to the north of the mouth of the Rio 

 San Francisco. This was the termination of my sea voyage, as the 

 heavy surf which breaks over the shallow bar of that river will not 

 allow jangadas to enter it. The village is situated a little way in- 

 land, and is hidden from the sea by a high embankment of sand, 

 which at this place is very much drifted by the wind; it is, how- 

 ever, recognised at a considerable distance, from the number of tall 

 cocoa-nut trees which grow near the shore. I was here particularly 

 struck with a fact, which goes a great way to explain the phenome- 

 non of a stem of a fossil tree being found passing through several 

 strata of sandstone. Many of the cocoa-nut trees have their stems 

 embedded, to the depth of 50 feet and upwards, in the embankment 

 of sand which stretches along the shore, and in many places is several 

 hundred feet broad; some of them, indeed, are so deeply em- 

 bedded, that the nuts can be gathered without climbing the tree. 

 Now as this sand has accumulated at different periods, particularly 

 during the prevalence of the north-east trade-wind, it must present, 

 if ever it becomes hardened, a vast number of irregularly horizon- 



* Mr Haidinger cites the suggestion made by Mr Dana, in his Mineralogy 

 (2d Edit. p. 307), that several of the above enumerated minerals were derived 

 from the alteration of lolite. 



