74 METHODS OF ANALYSIS. 



13. Malic Acid Value of Maple Products. Provisional. 



Weigh 6.7 grains of the sample into a 200 cc beaker and add water to make 

 a volume of 20 cc. Add 2 drops of ammonium hydroxid (specific gravity, 0.90), 

 1 cc of a 10 per cent solution of calcium chlorid, and 60 cc of 95 per cent alcohol. 

 Cover the beaker with a watch glass, heat for one-half hour on a water bath, 

 then turn off the flame and allow the beaker to stand overnight. Filter the 

 material in the beaker through good quality filter paper, wash the precipitate 

 with hot 75 per cent alcohol until the filtrate measures 100 cc, dry and ignite. 

 Add from 15 to 20 cc of tenth-normal hydrochloric acid to the ignited residue, 

 thoroughly dissolve the lime by heating carefully to just below boiling, cool 

 and titrate the excess of acid with tenth-normal sodium hydroxid, using methyl 

 orange as an indicator. One-tenth of the number of cubic centimeters of acid 

 neutralized by the ignited residue expresses the malic acid value. Run blank 

 determinations on reagents, using the same amounts, particularly of ammonium 

 hydroxid, as were used in the original determination, and make the necessary 

 correction. 



14. Detection of Coloring Matter. Provisional. 



Proceed as directed under " XXVIII, Coloring Matter," page 190. 



