52 Dr. Beddoes’s Obfervations on the 
the expanfive and effervefcent force of heat * * * § from the fur- 
rounding plain, the lava intermixed with granite, as if both 
had concreted together, the columns of an uniform texture in 
the adjacent parts of thefe hills, and the reft of the phenomena, 
even then led the author to fufpeft, “ a ftrong analogy be- 
“ tween granites and many particular volcanic concretions.” 
From the mountain of Efterelles, in the South of France, 
on the road from Frejus to Antibes, I have before me granite, 
gneifs, and fpecimens, in which feldfpath and grains of trans- 
parent quartz are diffufed through a pafte of the fame brownifh 
red colour and texture as the bafaltic columns at Dunbar in 
Scotland. 
Nothing is indeed more common, or more varioufly modified, 
than foflilsof this intermediate chara&er 4~. We frequently find 
a ground of jafper, and no doubt alfo of different varieties of 
whinftone, as will hereafter appear, with feldfpath and (hoerl 
at the fame time imbedded in them J ; and again with grains of 
feldfpath and quartz in fuch a manner as to leave it extremely 
doubtful, whether the rock ought to be named granite or por- 
phyry §. The varieties of fuch rocks will conduct us, by eafy 
fteps, from uniform bafaltes through the porphyries to granite. 
A chemical examination of the bafis of a number of thefe por- 
phyries would be very interefting ; yet I would not reft the 
theory of their formation altogether on the refult of analyfis. 
* The fight of them impreifed Ferber alfo with the fame idea. 
f 11 n’y a point de naturalises qui ne connoiffent le genre de roches, place entre 
le granit, les gneifs, et les porphyres, qui tiennent un peu des trois efpeces. Ifles 
Ponces, p. 90, 
J Haidinger, Traft quoted below, p. 47. 
§ Charpentier (Mineralogical Geography of Saxony, 4to, 1778. in Ger- 
man), p. 50. and elfewhere, finds himfelf in this ftate of uncertainty. 
The 
