462 Geological Soctefy. 



stances, such as peat, suriurhraiid, Bovev coal, &c. in which 

 the traces of vegetable origin are not ohliteraied. 



Submerged wood from peal mosses gave a brown oil 

 smelling of wood-tar, and refusing lo dissolve in naphth?, 



A compact pitchy-lookinii peat gave a fetid oil resem- 

 bling in odour neither wood-tar nor bitumen, and very 

 slightly soluble in naphtha. 



Bi'vey brown coal trave an oil resembling in odour that 

 of wood tar, but nuich more soluble in naphtha: that por- 

 tion of the oil which wa- insoluble in this menstruum h.id 

 a strong odour of wood smoke. 



The oil ot jet was almist perftctlv soluble in naphtha, 

 and smelled strongly ut petroleum ; but it aflTorded also em- 

 pyreumatic acetic acid. 



Thus it appears that there exists a class of fossils of vn- 

 dtiibted vegetable origin, which exhibit the gradual pro- 

 gress from wood to biiiinien, and in which this change 

 has been brought about by the action not of lieal but of 

 water. 



The experiments, however, of Sir James H^M seem to 

 show that heat with compression is also capable of con- 

 verting wood into coal. — A critical examitiation of this tact 

 was the next object of Dr. M.; and he found on healing 

 wood m close gun-barrels that a black coaly-l okins sub- 

 stance was indeed produced, but that ii consisted whi^lly of 

 ciarcoal, empvreumatic acid, and wood-tar, and did not 

 coiitam the smallest portion of real bitumen. Hence the 

 experiments alluded to do by no means prove the possibj- 

 lit\ of convertins vegetable matter into real coal by mere 

 htat. It appears however to Dr. M , that the consohdat 

 tioi) of hitunimiz:d vegetables into coal is not unlikcK to 

 be ;he efTect of subterranean heat. 



The paper concludes by showing the idi ntirv of" the pjich 

 procured from the distillation of wood and the piguieht 

 called Biitre ; and points out methods of (.btaiiuna it in a 

 state belter filttU than common bisire h^r the purposes of 

 the artist: and also enumerates several other uses (o which 

 this substance ni.iv be oeconomic:fllv app'ied. 



Some notes on the mineralogy nf 'he neighbourhood of 

 St. David's, in Penihroke-liire, hv Dr Kidd, ( Prof. ch> in. 

 O.xford, and member of thi (leoioaical Socie»v,) were read. 



The couniry about St. David's when viewed from an 

 eminence presents the appearance of at^ extensive uneven' 

 pl.iin. interspersed w ilh mimeniis deiaehed bills or rocky 

 sunmiits of an irregular conical shape. The two highps- of 



these. 



