SECTION THREE 



without. Ester wax, which is an opaque white or cream coloured 

 substance, is brittle when cut in thick slices, and it is recom- 

 mended, therefore, that only thin slices should be cut away 

 during the trimming of the block. The microtome knife bevel 

 angle should be between 20° and 30° (but not greater than 30°). 

 For further information the original paper should be consulted. 



ESTER WAX (i960) TROPICAL 



(H. F. Steedman, 19606) 



Recipe : 



Diethylene glycol distearate, neutral 300 gm. 

 Glyceryl monostearate . . . . 150 gm. 



Triethylene glycol monostearate . . 50 gm. 



This is prepared in the same way as the standard ester wax 

 (see page 504). 



Notes: 



The author (Steedman) states that once the wax is melted and 

 its temperature allowed to fall to 50° C, it will stay liquid at that 

 temperature for about four days. The liquid wax will become 

 cloudy if kept at that temperature, but it may be heated to 80° C. 

 and filtered. The filtrate will remain clear for at least another 

 four days, after which it should be heated and refiltered. Speci- 

 mens may be infiltrated at 50° C. if desired for four days or even 

 longer. 



Sections and ribbons may be cut at 3 to lo/x when the room 

 temperature is as high as 37-5° C, after the block has been at that 

 temperature for a week. Good sections and ribbons may be 

 obtained at this temperature provided the block and knife are 

 kept in a cool place (about 15° C). 



Steedman also calls attention to the diflterence between the 

 melting point and setting point of embedding waxes. This is 

 something which has not been generally realized; there is usually 

 a difference of several degrees between the two. It should be 

 mentioned here that in the case of paraffin waxes, the temperatures 

 given as the melting points are really the setting points. That is, 



505 



