358 The Commercial Products of the Sea. 



free from grease (even such as might arise from being 

 touched by the fingers), softening them in hot water, press- 

 ing them together with hot flat tongs, and then plunging 

 the joint into cold water. 



If, however, the heat is too great, the colours are much 

 deepened, so as to become almost black, as in the case of 

 moulded snuff-boxes ; for tortoiseshell, being less fusible 

 than horn, cannot be made soft enough to be moulded 

 without some injury to the colour. Accordingly, the 

 manufacturers never attempt to produce tortoiseshell combs 

 with ornamental open work by means of dies, but in the 

 following manner : — A paper being pasted over the tortoise- 

 shell, the pattern is drawn on the paper, and is then cut 

 out by means of drills and fine saws ; the paper is re- 

 moved by steeping in water, and the surface of the pattern 

 is finished by the graver. 



In making small side-combs, it is found worth while, in 

 order to save a costly material, to employ a machine, con- 

 sisting of a cutter working straight up and down, and of a 

 bed (on which the shell is laid) to which is given a motion, 

 advancing, by alternate inclination, first to one side and 

 then to the other. By this means the teeth of two combs 

 are cut at the same time; those of the one occupying the 

 intervals of the other. Such combs are called parted, the 

 saw not being used upon them. They are often made of 

 fine stained horn instead of tortoiseshell, and it is difficult 

 for the inexperienced eye to detect the difference. 



The appearance of tortoiseshell may be given to horn 

 by brushing it over with a paste made of two parts of lime^ 

 'one part litharge, and a little soda-lye, which is allowed to 

 dry. This is the same as the Indian hair-dye, and acts by 

 forming sulphuret of lead with the sulphur contained in the 

 albumen of the horn, producing dark spots, which contrast 



