140 Effects of Heat modified hj Compression. 



Tiace, in order todrj' it entirely, and afterwards polish it with 

 powdered pumice-stone and Tripoli. 



Manner of preparing the Ariide ivkich is to he varnished. 

 It is necessary to make use of walnut-tree, ash, or cherry- 

 tree wood, because these woods are porous, and when they 

 are perfectly dry they will turn better in the lathe; when 

 the article is shaped to your liking you must put it into a 

 stove to dry, atier which work it and polish it as if it was to 

 be completely finished, then apply the varnish in the manner 

 abpve described. 



If it is wanted to give the dibh a red colour, a little mi- 

 nium, or rather cinnabar, may be put into the varnish ; and 

 the same may be done with any other colour you wish to 

 give to the article varnished. 



XXIV. Account of a Series of Experiments, showing the 

 Effects of Compression in vwdifi/ing the Action of Heat. 

 By Sir James Hall, Bart. F.R.S. Edin.*- 



1. Anticnt Revolutions of the JSIincral Kingdom. — Vain Jt- 

 tempis to explain them. — Dependence of Geologij on Che- 

 mistry. — Importance of the Carbonate of Lime. — Dr. 

 Black's Discovery of Carlonic Acid subverted the former 

 Theories depending on Fire, hut gave Birth to that of Dr. 

 Button. — Progress of the Author's Ideas ivith regard to 

 that Theory. — Experiments with Heat and Compression^ 

 suggested to Dr. Hut ton in 1790. — Undertaken by the 

 Author in ] 798. — Speculations on which his Hopes of' Suc- 

 cess were founded. 



W HOEVER has attended to the structure of rocks and 

 mountains, must be convinced that our globe has not always 

 existed in its present state ; but that every part of its mass, 

 so far at least as our observations reach, has been agitated 

 and subverted by the most violent revolutions. 



* 'Esom.Tr -mactioiu of the Royal Sockfij of Edinburgh, vol. vii. 



Facts 



