MOUNTING IN GLYCERINE JELLY. 37 



absorbed by blotting-paper. Either of the two plans may 

 now be followed with regard to the jelly it may be liquefied 

 by placing the bottle in hot water, and then dropping the 

 liquid jelly upon the slide, or a small piece may be cut 

 from the bottle and put upon the object and the slide 

 gently warmed, when the jelly will diffuse itself through 

 the object, and will be found exceptionally free from air- 

 bubbles ; but should there be air-bubbles or not, it is of 

 great value to boil the jelly and object upon the slide, but 

 care must be used or the mount may be ruined. Should 

 the boiling be decided upon, the clip should be used, and 

 the slide held over the flame of a lamp ; it will at first begin 

 to bubble from the centre outwards, and if the slide be 

 carefully watched, a very perceptible crack may be seen 

 and heard : at this moment, and without delay, the slide 

 must be withdrawn from the heat and placed upon a cold 

 surface (an iron slab for instance), when the jelly will 

 rapidly set and air-bubbles be excluded. 



The mounts are easily cleaned from superfluous jelly, by 

 brushing with a soft tooth-brush under a running water tap, 

 the surface of the slide being allowed to dry spontaneously. 

 It will be found that the slide is free from glycerine smears, 

 which interfere much with the after-process of finishing. 



FIG. 252. 



The slides may then be finished by ringing with white 

 zinc varnish and the various coloured circles. 



Such is the method employed for mounting in glycerine 



X 2 



