16 THE ANALYST. MONTHLY RECORD OF ANALYTICAL RESEARCHES INTO FOOD. A NEW TEST FOR PICRIC ACID AND BINITROCRESOL. K. FLECK. Repert. Anal. Chem., 1886, No. 48.-As many makers of farinaceous foods are in the habit of colouring them, it has been thought they may occasionally use picric acid. This suspicion is, perhaps, not well founded, as picric acid would communicate a bitter taste, and so render the products unsaleable. As it is, however, possible picric acid (Welter’s Bitter) may be unintentionally substituted for binitrocresol (Victoria yellow), which is largely used in the trade, it becomes important for an analyst to be able to positively distinguish these two colouring matters, which hitherto has only been possible by tasting the alcoholic extract. If a solution of picric acid is concentrated in a small porcelain dish, and mixed withTHE ANALYST. 17 a few C.C. of 10 per cent. hydrochloric acid, the colour is at once destroyed. Binitro- cresol is also decolourized after a few minutes. I f now a piece of zinc is introduced, and allowed to act for one or two hours, the picric acid turns a fine blue; but binitro- uresol turns blood red. To apply the reaction to foods, they must be powdered and extracted with alcohol. The residue obtained after evaporating off the spirit must be oarefully tasted for bitter, and then treated with hydrochloric acid and zinc as described. L. DE I<.