8 CHELONIAD.E. 



jects be readily effected, but tlie substance can be rendered 

 ductile, compressible, capable of receiving any impression, 

 of being carved, moulded and polished, and even extended 

 by soldering pieces together by means of their own substance 

 reduced to powder. The whole of these processes are per- 

 formed by means of heat. 



The uneven curvature is first of all to be removed, and 

 the plate rendered perfectly flat. This is eflTected by im- 

 mersing it in hot water, and then allowing it to cool under 

 heavy pressure between smooth blocks of wood, or metallic 

 plates. The surface is then rendered smooth, and the thick- 

 ness equal, by scraping and filing away the rough and pro- 

 minent parts. In this way each plate receives an equal and 

 smooth surface. But it is in many cases desirable to em- 

 ploy larger pieces than can be obtained from single plates, 

 and two pieces are then united together in the following 

 manner : — The edges are bevelled off to the space of two or 

 three lines, and the margins when placed together overlap 

 each other to that extent. They are then pressed together 

 by a metallic press, and the whole is submitted to the action 

 of boiling water ; and by this means the two pieces are so 

 perfectly soldered together, as to leave no indication of the 

 line of union. By the application of heat, also, the tor- 

 toise-shell may be made to receive any impression by 

 being pressed between metallic moulds. 



No portion of this precious substance is lost or useless. 

 The filings and powder, which remain after these and the 

 other processes to which the shell is submitted, are placed 

 with any small fragments in metallic moulds, and by means of 

 pressure, exercised whilst they are exposed to the heat of 

 boiling water, they are formed into plates of any thickness 

 which may be required. 



Such is a very hasty and general sketch of the manner in 

 which this beautiful substance is rendered available to the 



