CHELONIA IMBRICATA. 43 



from the borders towards the centre, and can then be easily removed. These 

 plates vary in thickness and in transparency, and are consequently arranged in 

 classes of different value. Tortoise-shell is not considered of the best quality 

 unless the animal has reached a certain size, about one hundred and sixty pounds; 

 before that state, it is too thin. The quantity obtained varies much in weight in 

 different animals; fifteen pounds is the most obtained even from animals of the 

 largest size; yet this substance is so valuable that a Chelonia imbricata of the 

 same dimensions with a Green Turtle would sell for ten times as much. 



The lamina, when separated, are delicate and easily broken; yet, by certain 

 management, they can be made to take on any desired form; this is done by 

 immersing them for a time in hot water, and then placing them in moulds of iron 

 or wood; many portions may be joined together by cutting or scraping the edges 

 thin and placing them in accurate contact, in which position they must be retained, 

 and kept in boiling water till softened, then removed and suddenly cooled; and 

 thus can a continuous surface of great extent be produced, even sufficient to cover 

 pillars and doors, as practised by the ancients, with whom it was held in great 

 estimation. For information as to the procedure of arranging this substance for 

 diflferent purposes, as well as for the various uses to which it is applied, we may 

 refer to those works of art that treat on the subject. 



