Defcriptim of till Atigkfty Copper-Works, 369 



the difference of price, the latter is, upon the whole, preferable ; the prices of the two at 

 Liverpool being — coals 8s. 6d. per ton — flack 5s. per ditto. 



The fulphate of copper, however, is the richeftore that the mine yields, containing about 

 50 per cent, of pure metal. This is found in folution at the bottom of the mine, whence 

 it is pumped up into ciilerns, like tanners' pits, about two feet deep : of thefe pits there are 

 many ranges, each range communicating with a fhallow pool of confiderable extent. Into 

 thefe cifterns are put caft-iron plates, and other damaged iron veflels procured from Coal- 

 brook Dale j when the fulphuric acid enters into combination with the iron, letting fall the 

 copper in the form of a red fedinient very flightly oxided. The cifterns are cleared once 

 in a quarter of a year, when the fulphate of iron in folution is let off into the fhallow pool, 

 and the copper is taken to a kiln, well dried, and is then ready for exportation. The ful- 

 phate of iron remaining in the pool partly decompofes by fpontaneous evaporation, and lets 

 fall a yellow ochre, which is dried and fent to Liverpool and London. 



The fulphur produced in the roafting, after being melted and refined, is caft into rolls 

 and large cones, and fent to London. The cones are ufed chiefly for the manufa£lory of 

 gunpowder and fulphuric acid. 



Green vitriol and alum are alfo made in fmall quantities by a feparatc company j but to 

 thefe works ftrangers are not admitted. 



The number of men employed by the two companies is 1200 miners, and about 93 

 fmeltersj the miners are paid by the piece, and earn in general from a fliilling to twenty- 

 pence per day. 



The depth of the mine in the loweft part is 50 fathoms, and the ore continues as plen- 

 tiful as ever, and of a quality rather fuperior to that which lay nearer the furface. 



With regard to the annual quantity of ore raifed, little certain can be mentioned. The 

 Parys Mine has furnifhed from 5000 to 10,000 tons per quarter, exclufive of what is pro- 

 cured from the fulphate of copper in folution ; and as the two mines employ nearly equal 

 numbers of workmen, they probably afford about the fame quantity of ore. 



Adjoining to the fmelting-houfes is a rolling-mill, upon the fame conflruftion as malt- 

 mills, for grinding the materials for fire-bricks ; thefe confift of fragments of old fire-bricks, 

 with ciunch (a kind of magnefian clay found in coal-pits) procured from near Bangor-ferry, 



The port of Amlwch is chiefly artificial, being cut out of the rock with much labour and 

 expence, and is capable of containing 30 veffels of two hundred tons burthen ; it is greatly 

 expofed, and dangerous of accefs during high northerly winds, which drive a heavy fea up 

 the neck of the harbour. The two companies employ 15 brigs from loO to 150 tons 

 burthen, befidcs floops and other craft, all of which lie dry at low water. 



The various articles, the produce of the mines, which are exported, are the following : 

 L Coarfe regulus of copper from the fmelt'uig-houfes, 

 IL The richer copper ore roafied. 

 Til. The dried precipitate of copper from the vitriol pits. 

 IV. Refined fulphur. 

 V. Ochre. 

 VI. Alum. 

 VII. Green vitfiol. 



Vol. L— November 1797. 3B Tbe 



