2 LETTER VI. 



hardness and elasticity which we see it possesses. 

 Little also is necessary to be said on the subject of 

 lead, which is a compouiid of earth and sulphur, to- 

 gether with a small portion of mercury. It is found 

 in most countries, and is exceedingly plentiful in 

 England, particularly in Derbyshire. Tin is also a 

 metal which abounds so much in this country, that 

 the mines of Cornwall and Devonshire furnish the 

 greatest part of the tin consumed in Europe. Pewter 

 is a composition of which six parts arc brass, fifteen 

 Jead and one nimdred tin. Thin sheets of iron, coated 

 with tin, compose the manufacture called block- 

 tin, an article much in use. 



The bowels of the earth scarcely afford a material 

 f a more wonderful nature than mercury, or, as it is 

 often called, quicksilver. It is an imperfect metal, 

 neither ductile nor malleable, (i. e.) neither capable 

 of being drawn into length nor spread into breadth by 

 the hammer ; but consisting of a fluid substance, re- 

 sembling melted silver, and having a constant ten- 

 dency to form itself into globules. It is chiefly found 

 in Hungary, Spain, Italy and Peru, -The greatest 

 part of that consumed in England is brought from the 

 mines of Friuli, in Italy. It is of great use both in 

 manufactures and medicine. 



Mines of quicksilver are extremely unwholesome : 

 all mines indeed are so in a considerable degree ; but 

 those of tin are more unfavourable to health than those 

 of coal ; copper-mines more so than those of tin ; and 

 mines of quicksilver are so pernicious to the human 

 frame, that at the mines of Idra nothing can be more 

 shocking than to see the infirmities of those miserable 

 objects that cro\vd the hospital. Emaciated and crip- 

 pled, they have every limb contracted or convulsed ; 

 and some of them in a manner transpire quicksilver at 

 every pore. " There was one man," says Dr. Pope, 

 " who had not wrought in the mines above half a year, 

 and yet his body was so impregnated with this mi- 

 neral that a piece of brass put into his hand, or rub- 

 bed between his fingers, immediately became as 

 white as if had been washed over with silver." All 



