1040 IVORY NUT 



enco between the straight line and the curve of the tooth, on which account tho 

 blocks are rarely cut more than five or six inches long, unless for some specific object.' 

 Mr. P. L. Simnionds has given the following as tho weights of large elephants' 

 tusks : 



Ibs. 



Mr. Gordon Gumming had one weighing 173 



Mr. Cawood, of Graham's Town, had a pair weighing . . .330 

 From Camaroon, shipped to Liverpool . . . . 164 



A tusk imported at Bristol 147 



At the Great Exhibition of 1851, tusk 162 



IVORY BLACK (Noir d'ivoirc, Fr. ; Kohle wn Elfcnbein, Ger.) is prepared 

 from ivory-dust, by calcination, in the very same way as is described under BONH 

 BLACK. The calcined matter being ground and levigated on a porphyry slab affordo 

 a beautiful velvety black, much used in copperplate printing. 



IVORY, FICTILE, is plaster-of-Paris which has been made to absorb, after 

 drying, melted spermaceti, by capillary action ; or it may be prepared according to 

 Mr. Franchi's process as follows : Plaster and colouring matter are employed in tho 

 proportions of a pound of superfine plaster-of-Paris to half an ounce of Italian yellow 

 ochre. They are intimately mixed by passing them through a fine silk sieve, and a 

 plaster cast is made in the usual way. It is first allowed to dry in the open air, 

 and is then carefully heated in an oven ; the plaster cast, when thoroughly dry, is 

 soaked for a quarter of an hour in a bath containing equal parts of white wax, sperma- 

 ceti, and stearine, heated just a little beyond the melting-point. The cast on removal 

 is set on edge, that the superfluous composition may drain off; and before it cools, the 

 surface is brushed, -with a brush like that known by house-painters as a sash tool, to 

 remove any wax which may have settled in the crevices ; and finally when the plaster 

 is quite cold, its surface is polished by rubbing it with a tuft of cotton wool. 



IVORY WITT or Vegetable Ivory. This substance is the hardened albumen 

 of the seeds of a species of palm known as the Phytelephas macrocarpa. The palm 

 grows in the low valleys of the Peruvian Andes. The seeds are known in commerce 

 as Corosso nuts, and are enclosed in large capsular fruit, somewhat resembling a 

 negro's head, and hence locally termed Cabeza de Negro. The albumen has a structure 

 somewhat resembling that of ivory ; but it more nearly resembles white wax. The 

 ivory nut is occasionally used by the turner for small ornamental objects, but not for 

 any important work. 



KND OP THE SECOND VOLTIDO:. 

 4 



I/>XDON : riUNTKI) BY 



."."OTTISWOODK AM) CO., XF.W-STREFT SQUAttH 

 AND PAUMAMK.NT ; 



