40 



METHODS. 



No unvarying method can be used for the examination of confectionery, owing to 

 the wide range of material that enters into its composition, and much discretion 

 must be used in making analyses in view of this fact. Portions may be advan- 

 tageously isolated from each other mechanically, and after being roughly sepa- 

 rated they are subjected to a preliminary treatment by agitating with warm 

 water and allowed to stand for from 10 to 12 hours, when the water solution and 

 insoluble residue are examined separately. According to whether the material is 

 chiefly nitrogenous (as candied fruits, etc.) or of the carbohydrate class, a different 

 line of examination should be adopted. In general, the following outline may be 

 applied to the separated portions: 



Digest with warm 20 per cent alcohol and filter. 



Bujard and Baier recommend extracting with alcohol, adding water and pouring 

 10 per cent hydrochlic acid over the residue and observing the degree of yellow color 

 produced, an immediate yellow indicating picric acid and a yellow after a short 

 time indicating dinitrocresol. If treated with metallic zinc for from one to two hours, 

 picric acid gives a blue color and dinitrocresol a clear blood red. 





Hilfsbuch, p. 211. 



