'VANILLIN 



13S 



Coumarin 



Vanillin 



Benzole Arid. 



$ 



(f/ V 



M 

 ^V 



-// 



Crystals at Ordmaru Temperature 



^ 



U" 



^ 



K 



Crystals at 



LJ 



Crustals at eo'tosz'C, 



FIG. 58. Examination of crystals by means of a thermo-stage. (1) Crystals at 

 ordinary temperature. (2) Slide heated to 54-56 C. when Cdumarin melts, 

 the crystals of vanillin and benzoic acid remain normal. (3) Crystals heated 

 from 80-82 C., at which temperature vanillin melts. 



