PRESERVATION OF SPECIMENS IN PLASTICS 



Figure 12. — A transfer pipette of suitable size, with the sucking end cut off and the 

 bulb wrapped with cellophane to fit the flask's neck, provides a vented stopper 

 which condenses the vapor and prevents its escape. Because the flask might break, 

 it is safer to heat it under a fume hood, and to leave it there until contents are cool. 



inches and to tie the film at both top and bottom with string or heavy 

 thread. 



3. Attach a utility clamp (or its equivalent) to the neck of the flask 

 to serve as a supporting handle and then set it in a water bath on an 

 electric hot plate. A ring stand may be used in connection with the 

 clamp to hold the flask in position during the early stages of the heat- 

 ing, but as soon as the liquid begins to thicken it is better to hold the 

 flask by hand so that it can be more easily manipulated in case the 

 polymerization tends to speed up unduly. A water bath with concen- 



