FRUITS AND FRUIT PRODUCTS. 79 



(2) SULPHATES AND CHLOBIDS. 



Wash the ash into a 50 cc flask and make up to the mark with water. Evapo- 

 rate 25 cc of this solution several times to dryness with concentrated hydro- 

 chloric acid and determine the sulphates by precipitation with barium chlorid. 

 Multiply the weight of barium sulphate by 0.7469 to obtain the weight of sul- 

 phates calculated as potassium sulphate. 



In the other portion of the solution determine the chlorln by the Volhard 

 method, as given under " III. Inorganic Plant Constituents," on page 23. The 

 nitric acid added before making the titration will, if it contain enough nitrous 

 ox id, completely destroy the red color of the methyl orange and leave a clear 

 solution for the titration. Calculate the chlorin as per cent of sodium chlorid. 

 Pure fruit jellies and jams give practically no chlorids or sulphates in this 

 amount of ash, but glucose goods may give appreciable amounts. If it is 

 desired to make a complete ash analysis of juices or fresh fruits, much larger 

 amounts must be ashed. 



6. Total Acidity. Provisional. 



Dilute 25 cc of the solution of jelly or diluted sirup (see (a), p. 77), or 10 

 grams of juice or fresh fruit, with recently boiled distilled water to about 250 

 cc, or less if the sample be not highly colored ; add phenolphthalein and titrate 

 the acid with tenth-normal alkali. In case of highly colored products litmus 

 paper may be used instead of phenolphthalein. Calculate the results as 

 sulphuric acid. 



7. Volatile Acids. Provisional. 



Dissolve 25 grams of substance, dilute to 50 cc, and distil in a current of 

 steam, as directed under "XIII. Wines," page 86, section 13. Each cubic centi- 

 meter of tenth-normal alkali is equivalent to 0.006 gram of acetic acid. 



8. Detection of Free Mineral Acids. Provisional. 

 Use Hehner's method, as given under " XVI. Vinegar," page 104. 



9. Nitrogen. Provisional. 



Use 5 grams of jelly or other fruit product, or 10 grams of juice or fresh fruit, 

 for the determination of nitrogen according to either the Gunning or the 

 Kjeldahl method. ("I. Fertilizers," p. 5.) Express results as protein (nitro- 

 gen multiplied by 6.25). 



10. Sucrose. Provisional, 

 (a) BY POLARIZATION. 



Determine by polarizing before and after inversion, as directed on page 40, 

 under " VI. General Methods." 



(b) BY REDUCTION. 

 Determine as directed on page 41, under " VI. General Methods." 



11. Reducing Sugars. Provisional. 

 Determine as directed on page 42, under " VI. General Methods." 



