515 



without an expression of sorrow for the untimely death of that 

 amiable and distinguished philosopher. Mr. Whewell and Mr. 

 Murchison alluded in most feeling terms this morning at the Ge- 

 neral Meeting to this melancholy event, which is too recent and too 

 painful to myself and others to allow me now to dwell longer upon it. 



Before quitting the subject of vegetable petrifactions, I ought 

 to mention a memoir just published, by Mr. H. R. Goppert, 

 Professor of Botany at Breslau, " On the various Conditions in 

 which Fossil Plants are found, and on the Process of Lapidifica- 

 tion*." He has instituted a series of most curious experiments, 

 and his success in producing imitations of fossil petrifactions has 

 been very remarkable. I have only space to allude to one or two 

 examples. He placed recent ferns between soft layers of clay, 

 dried these in the shade, and then slowly and gradually heated 

 them, till they were red hot. The result was the production of so 

 perfect a counterpart of fossil plants as might have deceived an ex- 

 perienced geologist. According to the different degrees of heat 

 applied, the plants were obtained in a brown or perfectly carbon- 

 ized condition, and sometimes, but more rarely, they were in a black 

 shining state, adhering closely to the layer of clay. If the red heat 

 was sustained until all the organic matter was burnt up, only an im- 

 pression of the plant remained. 



The same chemist steeped plants in a moderately strong solution 

 of sulphate of iron, and left them immersed in it for several days 

 until they were thoroughly soaked in the liquid. They were then 

 dried and kept heated until they would no longer shrink in volume, 

 and until every trace of organic matter had disappeared. On cool- 

 ing them he found that the oxyd formed by this process had taken 

 the form of the plants. Professor Goppert then took fine vertical 

 slices of the Scotch fir, Pinus sylvestris, and treated them in the 

 same way ; and so well were they preserved, that, after heating, the 

 dotted vessels so peculiar to this family of plants were distinctly vi- 

 sible. A variety of other experiments were made by steeping 

 animal and vegetable substances in siliceous, calcareous, and me- 

 tallic solutions, and all tended to prove that the mineralization of 



* PoggendorfF, Annalen der Physik und Cliemie, vol. xxxviii. part 4. 

 Leipsic, 1836. 



