DETECTION OF ADULTERATION 6 1 



salicylic acid in the usual manner with a ferric 

 compound. 



Saccharin. — A suitable amount of the sample 

 (50 or 100 c.c.) is acidified with dilute (25%) 

 sulfuric acid and extracted with a mixture of 

 equal parts of petroleum spirit (boiling below 60°) 

 and ether. The solvent is evaporated at a gentle 

 heat. The presence of saccharin in the residue 

 may be detected by the taste. 2 c.c. of a 

 saturated solution of sodium hydroxid are added 

 and the dish heated until the residue dries and 

 then to 2io°-2is°, and maintained thus for half 

 an hour. The saccharin is converted into salicylic 

 acid, which may be detected in the residue by 

 acidulating it with sulfuric acid and applying the 

 ferric chlorid test. If salicylic acid be present 

 originally in the sample, the residue from the 

 petroleum spirit and ether solution is dissolved 

 in 50 c.c. of dilute hydrochloric acid, bromin 

 water added in excess, the liquid shaken well, 

 and filtered. Salicylic acid is completely removed 

 as a brominated derivative. The filtrate is made 

 strongly alkaline with sodium hydroxid, evapo- 

 rated, and fused as described above. 



Sodium Carbonate and Sodium Acid Car- 

 bonate. — These substances are occasionally added 

 to milk to prevent acidity due to decomposition. 

 Barthel recommends a test devised by Hilger. 

 SO c.c. of the milk are diluted with 250 c.c. of 



