DETECTION OF ADULTERATION 61 
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 cc. of a 
saturated solution of sodium hydroxid are added 
and the dish heated until the residue dries and 
then to 210°-21s°, and maintained thus for half 
anhour. 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. 
50 c.c. of the milk are diluted with 250 c.c. of 
