422 Scientific Intelligence. 



A basalt from the Rhine consisting of labradorite about 54 p. c, 

 pyroxene 24, chrysolite 10, with titanic iron 10, and water, 2 p. c, 

 afforded him 



Unchanged Basalt. Basalt altered. 



A. B. 



Alumina, 



Silica, . 



Lime, . 



Magnesia, 



Oxyd of iron and manganese, 



Titanic acid, 



Potassa, .... 



Soda, . . . 



Water, . 



100 100 



283 228 



63 43 



39 29 



80 78 



6 6 



7-4 26 



22-2 7-4 



150 350 



615-6 5290 



Here two-thirds of the alkalies have disappeared, showing that the 

 decomposition of the feldspar was far advanced. The result of the 

 changes in both cases is to produce as the residue, a hydrated silicate 

 of alumina or a clay. The removal of the silica is shown by M. Ebel- 

 men to be independent of the alkalies present. The decomposition is 

 attributed by him to carbonic acid and oxygen present in waters, to 

 organic matters living or in course of decomposition, and the phenomena 

 of nitrification. 



7. Phosphate of Lime in Greensand and Marl, (from De la Beche's 

 Address to Geol. Soc, London, Proc. Geol. Soc, May, 1849, p. Ixxxii.) 



The agricultural importance of phosphate of lime has of late years 

 caused more search to be made for this substance than formerly, though 

 its occurrence as a component part of certain organic remains and of 

 some rocks has been long known. Mr. Paine, of Farnham, having 

 pointed out that certain beds contained phosphate of lime in sufficient 

 abundance to render them of much agricultural value, our colleague, 

 Mr. Austen, was induced to investigate the mode of occurrence of the 

 phosphate of lime in his own neighborhood, that of Guildford. He 

 found that the phosphate of lime nodules are abundant in the upper 

 greensand. They also occur in the gault, in two distinct beds, remark- 

 ably persistent in the district. In describing the position of these beds, 

 Mr. Austen takes occasion to point out the inaccuracy of the published 

 geological maps and sections of the district, calling attention to the 

 beds of very different parts of the cretaceous series which are brought 

 up along the escarpment of the North Down range. Having ascer- 

 tained the facts connected with the layers of phosphate of lime nodules 

 in the vicinity of Guildford, Mr. Austen examined the neighborhood ot 

 Farnham, and found the component, parts of the cretaceous series the 

 same as near Guildford, with the exception that sandstones, occasionally 

 cherty, represent near Farnham the firestone on the eastward and the 

 malm rock on the west, differing however from them in containing 

 scarcely any carbonate of lime. This Mr. Austen infers to have hap- 

 pened from a stream of water, having a course somewhat north ana 

 south, drifting rather coarse materials with little calcareous matter in 

 this locality. 



