Correspondence. 277 



deposit at Seedrapett, to which Mr. Cunliffe alludes in your last 

 number. 



The discoveries of Messrs. Kaye and Cunliffe have not been confined 

 to the search for fossils ; but they also discovered detached specimens 

 among the silicified trees of Trivicary, which shew a most perfect 

 exogenous structure, with perfectly distinct medullary rays, annular 

 rings, and detached longitudinal tubular vessels ; and in one, the number 

 of these vessels, and the colour of the whole, give the exact appearance 

 of a piece of cane, except that the medullary rays are distinctly visible. 

 Some have imagined these appearances to indicate a resemblance to the 

 structure of coniferous wood j but Lindley mentions, that coniferous wood 

 is distinguished by the absence of vessels in the woody fibre, and besides, 

 the shapes of the trunks 100 feet in length without a branch, marks 

 a wide difference from any existing species. The specimens in Mr. 

 Kaye's possession which I have been obligingly favoured with a sight of, 

 are of large size (one nearly four inches square) ; and deserve well to be 

 figured in Lindley and Hutton's Fossil Flora, and I have no doubt they 

 would be highly valued in Europe. The solution of silica, alluded to in 

 the paper on Petrifaction, is probably the common potash silicate, and 

 the petrifying agent is the fluosilicic acid of English chemists. This 

 gas has the property of depositing a portion of its silica on coming 

 into contact with water, and forms in consequence, long tubes on the 

 end of the beak of the retort, from which it is evolved when the end of 

 the retort is played into water ; and it is remarkable, that in the are- 

 naceous matrix of the Trivicary woodstone, fissures sometimes eighteen 

 inches long and an inch in diameter are found composed of water-worn 

 grains of sand, aggregated by a mineral of a bluish lead colour, much 

 resembling in fracture and appearance some of the varieties in the trap 

 dykes of Amboor. I have seen balls with a somewhat similar structure 

 from the same place, and the arenaceous matrix also presents an appear- 

 ance, which in my opinion plainly shews, that it is not an unaltered 

 sedimentary deposit, for although the quartzose sand is I think un- 

 doubtedly water-worn, yet it is mottled with spots of kaolin earth, of 

 a very pure white, which has been by some mistaken for lime, &c. &c 

 disseminated through the mass. 



Regarding your note at page 36, suggesting the use of the 

 term " porcelain clay," instead of kaolin, the terms of course mean the 

 same ; but I much doubt if any more definite idea would be afforded 

 to the generality of readers by the use of either one or the other : but 

 I used the term kaolin, because it is generally made use of as applied 

 more to an earth than a clay. Berthier classes kaolin as clays (ar- 



2 N 



