SLITTING AND POLISHING BENCH. 195 



use with the freezing microtome it will be unnecessary 

 to wet it. 



The top plate would be better made of steel, or even 

 of glass, unless razor-guards be used, as though it is 

 easy after some practice to prevent cutting into the brass, 

 yet this invariably happens to beginners. Do not forget 

 to well wash the microtome and knife before putting 

 them away, and to grease them with some heavy lubri- 

 cating oil. 



We now come to the preparation of sections of hard sub- 

 stances, such as bone, coal, rocks, and minerals generally. 

 Some operators start with a fragment chipped from a 

 large specimen ; but without doubt when several sections 

 have to be cut, the 

 best plan is to resort 

 to what is termed 

 slitting, being done 

 by the microscopist 

 himself or sent to the 

 lapidary, who will cut 

 slices for a very small 

 charge. 



If the operator 

 desires a bench of 

 his own, it would be 

 advisable to have the 

 slitter and laps inter- 

 changeable, so that 

 they may run on the 

 same centres. The 



Fir 



woodcut, Fig. 182, will 



show how such a bench may be constructed. 



The slitter is a thin wrought-iron disc about 1 1 inches in 

 diameter by about A of an inch in thickness, and when used 



O 2 



