100 



THE ART OF MAKING MICROSCOPE SLIDES 



Casting block 



Fig. 39. Folding a cardboard box. a. The two long edges of a rectangular card are folded to 



meet in the center. 



Fig. 40. Folding a cardboard box — {continued), h. Folds are flattened out and the short edges 



are folded not quite to the center. 



Fig. 41. Folding a cardboard box — {continued), c. Corners are folded over. 



crammed into the tube. When these are 

 completely molten, and most of the vola- 

 tile solvent has evaporated, the object is 

 removed with a pipet, or forceps, and 

 placed in a dish of pure wax for an hour 

 or two before being transferred to a second 

 dish of pure wax for the time necessar}^ to 

 secure complete impregnation. 



There is no method of forecasting how 

 long an object will take to l^ecome com- 

 pletely impregnated with wax. It is very 



easy to find out, when one has started to 

 cut sections, that the impregnation is not 

 complete; but there is no basis save ex- 

 perience on which to base the timing in 

 the different baths. If the object is to be 

 transferred directly from solvent to wax, 

 at least three baths should be employed, 

 for nothing is more destructive to a good 

 section than the presence of a small quan- 

 tity of the clearing agent in the embedding 

 medium. To an absolute beginner seeking 



