104. SHELLS. Class VI. 



other countries. Moft of our coafts produce them 

 naturally, and in fuch places they are taken by 

 dredging, and are become an article of com- 

 merce, both raw and pickled. The very fhells, 

 calcined, become an ufeful medicine as an abfor- 

 bent. In common with other fhells, prove an ex- 

 cellent manure. 



Stews or layers of oyflers are formed in places, 

 which nature never allotted as habitations for them. 

 Thofe near Colchefter have been long famous ; at 

 prefent there are others, that at left rival the former, 

 near the mouth of the "Thames. The oyfters, or their 

 ipats, are brought to convenient places, where 

 they improve in tafte and fize. It is an error to 

 fuppoie, that the fine green obferved in oyfters 

 taken from artificial beds, is owing to copperas*, 

 it being notorious how deftructive the fubftance 

 or the iclution of in is to all fifli. I cannot give 

 a better account ot the caufe, or of the whols. 

 treatment of oyfters, than what is preferred in 

 the learned BHhop Sprat's Hiftory of the Royal 

 Society, from p. 307 to 309. 



c In the month of May the oyfters caft their 

 * fpaun, (which the dredgers call their fpats :) it 

 - is like to a drop of candle, and about the big- 

 w nefs of a halfpenny. 



4 The fpai cleaves to Hones, old oyfter-ihells, 

 c pieces of wood, and faeh-like things, at the bot- 

 '• torn of the lea. which they call cidich. 



■ 'Tis 



