528 



Manner of 

 making the 

 wooden cups. 



"Rti varniiht 



ACTION OF HEAT MODIFIED 



Mix lamp black wilh varnifli and a little lurpentine, with 

 a hair pencil, and lay one coat on the piece ; when this is 

 dry, lay on another, and repeat the procefs till four coats 

 have been laid on, taking care to let each dry before the ap- 

 plication of the next. When the laft is dry, put the piece 

 into a ftove or oven to complete the drying, aad then polill) 

 it with pumice and Tripoli powder. 



Method of preparing the Fiece intended to be vamijhed. 



Make the cups of hazel, alder, or cherry-tree, which are 

 preferable to other woods for this ufe, becaufe they are pofous 

 when perfedly dry, and do not warp. Form them according to 

 fancy, and dry them in an oven. The work muft be poliftied as 

 if it were complete; and afterwards lay on the varnifti as 

 already prefcribed. 



If it fhould be wiflied to give a red ground to the article, 

 mix a little minium, or rather cinabar, with the varnilh. Any 

 other colour may in like manner be mixed with it, as may bell; 

 pleafe the fancy of the operator. 



Vioient revo- 

 lutions of the 

 furface of the 

 Slobe. 



XII. 



Account of a Series of Experiments, ^(hewing the EffeSis of Coni' 

 jprejfton in modifj/ing the ABion of Heat*. By Sir James 

 Halx., Eurt. F.R.S. Edinburgh. 

 Section I. 



Ancient Revolutions of the Mineral Kingdom, — Vain Attempts 

 to explain them. — Dependance of Geology on Chemifiry. — Im- 

 portance of the Carbonate of Lime. — Dr Black's Difcovery 

 of Carbonic Acid fuhverted the former theoi'ies depending on 

 Firey but 'gave Birth to that of Dr. Hutton. — Progrefs of 

 the Author's Ideas xvith Regard to that Theory. — Experiments. 

 with Heat and Comprejffion, fuggejled to Dr. Hutton in 

 1790. — Undertaken by the Author in 1798. — Speculations on 

 ivhick his Hopes of Succejs were founded. 



W HOEVER has attended to the firufture of rocks and 

 mountains, muft be convinced, that our globe has not always 



exifled 



* The highly interefting experiments of Sir James Hail upon 



. the eftefts of hej^t modified by cgmpieflloii, were communicated ta 



the 



