LIST OF REAGENTS. 465 



GLYCERIN JEILY. 



Preparation. — Soak gelatin in water till soft ; pour off excess 

 of water; melt, and while still fluid but cool add one- 

 eighth of its bulk of white of egg : mix thoroughly : boil : 

 strain through flannel : to strained fluid while still hot add 

 half its volume of a mixture of equal parts of glycerin 

 and camphor water. 



Use. — For mounting microscopical objects which are too 

 transparent when mounted in balsam (see Introduction, 

 p. xxxi). 



FAKEANT'S MEDIUM. 



Preparation. — Dissolve 400 grms. white gum arable in 400 c.c. 

 water without heat, stirring occasionally: add 200 c.c. 

 glycerin: strain through clean flannel if necessary. Keep 

 in a stoppered bottle with a piece of camphor. 



Use. — Same as glycerin -jelly, but it is used cold, and objects 

 may be transferred to it direct from water. It soon 

 hardens at the edges : ringing with varnish is therefore 

 unnecessary. 



CANADA BALSAM. 



Preparation. — May be used as bought from the chemist, or 

 diluted to a suitable consistency with benzol. Still better, 

 evaporate to dryness : powder and dissolve in chloroform, 

 ■ benzol, or xylol : benzol is best. 



Use. — The most useful of all media for mounting stained 

 objects. (For method of using, see Introduction, p. xxxi.) 



V. MICBOTOMIST'S MEDIA. 

 GUM-WATER. 



Preparation. — Dissolve gum-arabic in 3 times its weight oi 

 water without heat : allow to stand : strain if necessary. 



Use. — ^For impregnating objects to be out by the freezing 

 microtome. 



PARAFFIN. 



Melting-point about 56° C. 



Use. — For imbedding objects to be cut into sections. 



HH 



