498 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 



To finish it, turn the dogs' ears round against the ends of the box, 

 turn down outside the projecting flaps that remain, and pinch them 

 down. A well-made post-card tray will last through several im- 



beddings, and will generally 

 work better after having 

 been used than when new. 

 (From Mr. Lee's ' Microto- 

 mist's Vade-mecum.') 



To imbed in such a tray, 

 or similar receptacle, some 

 melted paraffin (or other 

 ' mass ') is poured into it ; 

 at the moment when the 

 mass has cooled so far as to 

 have a consistency that will 

 not allow the object to sink 

 to the bottom, the object is 

 placed on its surface, and 

 more melted mass poured on 

 until the object is covered 

 by it. Or, the paper tray 

 being placed on cork, the 

 object may be fixed in posi- 

 tion in it whilst empty by 

 means of pins, and the tray 

 filled with melted mass at 

 h 1 one pour. (The pins can be 



removed from the mass 

 when cold.) 



In either case, when the 

 mass is cold the paper is removed from it before cutting. 



As soon as the tray is filled, and the object in position, cool it on 

 water, holding it above the surface with only the bottom immersed 

 until all the paraffin has solidified, as if you let it go to the bottom 

 at once you will probably get cavities filled with water formed in 

 your paraffin. Or you may put it to cool on a block of cold metal or 

 stone. 



A better plan is to 

 employ sets of two 

 pieces of type-metal, 

 cast in rectangular form 

 of various heights and 

 capable of being placed 

 together as in fig. 408 ; 

 in this way a suitable 

 box is formed, and, the 

 end of the shorter arm 

 being triangularly en- 



FIG. 407. 



FIG. 408. - Type-metal case for imbedding. 



larged outwards, it is closed sufficiently to retain the mass. Placed 

 in this way, with the short arms nearer to or farther from each 

 other as a less or greater imbedding mass is required, they are set 



