Miscellaneous* ^ST 



four degrees, and often furnished with large cicatrices pf branches ; they 

 are consequently only fragments, scattered about in those localities 

 during the cultivation of the forests and fields, of stems which very 

 probably occur in the interior of the sandstone rock, from which they 

 only project singly. Smaller stems or branches, of less than one 

 foot in thickness, are wanting ; and it is remarkable that I have never 

 found any such in the carboniferous formation, whilst in the petrified 

 forests of the tertiary formation, for example, in Egypt and Java, these 

 are even more abundant than the larger ones. They all belong to 

 coniferous plants, similar to the Araucarice ; one of them decidedly 

 is a new species, Araucarites Schrollianus (named in honour of 

 M. B. Schroll), and the other is A. Brayidlingii^ which has been 

 found in the carboniferous strata of England*, Saarbriicken, Bohemia, 

 and Silesia. I obtained a specimen of the former species, six feet in 

 length and three feet in thickness, from M. Schroll ; it is now an 

 ornament of the Palseontological portion of the Botanic Garden at 

 Breslau. 



As regards the process of petrifaction itself, the previous experi- 

 ments and observations mentioned by the author in the years 1836 

 and 1837, at the meetings of German Naturahsts at Jena and Prague, 

 and in the * Fossil Flora of Silesia,' published in 1844, were, at the 

 reading of this paper before the Silesian Society, Nov. 27, 18.57, 

 brought together with his more recent ones, and illustrated by the 

 exhibition of specimens. The former started from woods discovered 

 in the existing world, petrified by carbonate of lime or oxide of iron, 

 to which native copper has very recently been added as a petrifying 

 medium, as this has filled up cells and vessels in a fragment of beech- 

 wood communicated to me by my honoured friend Haidinger. The 

 examination of fossil woods shows, that after they are filled up by 

 the various petrifactive media (carbonate of lime, silica, the various 

 forms of oxides of iron and copper, cinnabar, baryta, gypsum, lead- 

 glance and clay), in by far the greater number of cases, notwith- 

 standing the solid, perfectly mineralized appearance of the exterior, 

 a larger or smaller quantity of cells and vessels are still present, which, 

 probably in consequence of the long duration of the process, have 

 become changed into brown-coal, although retaining the cellulose 

 here and there ; hence the prevaihng brown colour of petrified woods, 

 which, however, are still frequently tinged in various ways by oxide 

 of iron. Other differences, which can only be hinted at here, may 

 be explained by the state in which they were at the time of fossili- 

 zation. We need only refer to the infi>iitely variable texture of the 

 woody plants of an existing forest. A complete displacement of the 

 organic parts very rarely takes place, as perhaps in the so-called 

 pyritized woods, and woods mineralized by brown iron-stone, as also 

 in the crystalline wood-opals of Hungary, Bohemia, the Rhine di- 

 stricts, &c., and there in consequence of a process of decomposition 

 of the organic matter. In the latter, cells still occupied by air- 

 bubbles are often found. 



In conclusion, the process of solution of the petrifactive minerals 



[* Dadoxylon Brandlingi of M.onWs ^ Catalogue of British Fossils.' — Ed.] 



