23B SCIENTIFIC NEWS. 



Woodchan^rrt Thus it appears, that there exists a class of fossils of 



to bitumen by undoubted vegetable origin, which exhibit the gradual 

 water. ^ , . ,. . , , . , 



progress from wood to bitumen, and in which tins change 



has been brought about by the action, not of heat, but of 



water. 



Experiments The experiments however of Sir James Hall seem to 



nt Sir James s p jOW that heat with compression is also capable of con- 

 Hail, . r .... 



verting wood into coal. A critical examination of thi* fact 



was the next object of Dr. M., and he found on heating 

 wood in close gunharrels, that a black coaly looking sub- 

 substance was indeed produced, but that it consisted wholly 

 of charcoal, empyreumatic acid, and wood tar; and did not 

 contain the smallest portion of real bitumen : hence the 

 experiments alluded to do by no means prove the possibility 

 of converting vegetable matter into real coal by mere heat. 

 It appears, however, to Dr. M., that the consolidation of 

 bituminized vegetables into coal is not unlikely to be the 

 effects of subterranean heat. 

 Bistre the pitch. This paper concludes by showing the identity of the 

 «j wood. pitch procured from the distillation of wood and the pig- 



lmnrovement roent called bistre ; points out methods of obtaining it in a 

 and uses of it. state better fitted than common bistre for the purposes 

 of the artist; and also enumerates several other uses, to 

 which this substance may be economically applied. 

 MTnerakspy of Some notrs on the mineralogy of the neighbourhood uf 

 St » St. David's in Pembrokeshire, by Dr. Kidd, Prof. Chem. 

 at Oxford, and Hon. M. G. S., were read. The Country 

 about St. Davids, when viewed from an eminence, presents 

 the appearance of an extensive uneven plain, interspersed 

 with numerous detached hills or rocky summits of an 

 irregular conical shape. The two highest of, these hills 

 are Penberry and Carn-Llidy, the western portion of the 

 latter of which forms the promontory of St. David's head. 

 These hills present no appearance of stratification, and are 

 composed of felspar and hornbiend in various proportions 

 and states of aggregation.* They are each surrounded by 

 mantle shaped strata of slate, elevated at a high angle, and 

 presenting the characters of grauwacke slate: this latter is 

 traversed by veins of quarts, tffcn which very hue speci- 

 mens of rock crystal are procur^^ No carbonate of lime 



appears 



