78 METHODS OF ANALYSIS. 



grams of freshly ignited asbestos to absorb it ; dry for from twenty to twenty- 

 four hours in a water-jacketed oven. In case of jellies that contain starch 

 or insoluble matter, solids may be determined as directed below under (b). 



(2) BY CALCULATION FEOM SPECIFIC GRAVITY. 



Determine the specific gravity of the solution of jelly or diluted sirup, or of 

 the juice as directed under " X. Saccharine Products," page 65. 



(b) IN FRESH AND DBIED FBUITS, JAMS, MARMALADES, PRESERVES, AND CANNED 



GOODS. 



Weigh about 20 grams of pulped fresh fruit, or such an amount of fruit 

 products as will give not more than 3 or 4 grams of dried material ; add a few 

 cubic centimeters of water, mix thoroughly, and dry as in (a) (1) above. 



4. Insoluble Solids. Provisional. 

 (a) KREMLA'S METHOD, MODIFIED. 



Transfer 50 grams of the sample, by the aid of warm water, to a mortar and 

 thoroughly macerate ; then transfer to a muslin filter and wash thoroughly with 

 warm water, care being taken at each addition of water to stir the pulp thor- 

 oughly. Collect the filtrate in a 500 cc flask, cool, and make up to volume. 

 Usually this amount is sufficient to remove all soluble material. In extreme 

 cases increase the washings to 1,000 cc; transfer the insoluble residue to an 

 evaporating dish, dry, and weigh. 



(b) GERMAN OFFICIAL METHOD. 



Transfer a weighed portion of the fruit product to a graduated flask, add 

 water, shake thoroughly, and make up to volume. Allow to settle and either 

 filter or decant off the supernatant liquid. Determine the soluble solids in an 

 aliquot. Total solids less soluble solids equals insoluble solids. The fruit must 

 be thoroughly macerated; the use of a mechanical, shaker is advisable. 



5. Ash. Provisional, 

 (a) DETEBMINA.TTAIV. 



Evaporate to dryness 50 cc of the solution of the jelly or diluted sirup (see 

 1 (a), p. 77), 25 grams of juice or of fresh or canned fruit, or 10 grams of 

 jam, marmalade, preserves, or dried fruit, and determine the ash as directed 

 under " VI. General Methods," page 38. 



(b) CONSTITUENTS OF THE ASH. 



(1) ALKALINITY. 



Into the platinum dish containing the ash run an excess of fifth-normal nitric 

 acid, heat to boiling, cool, and add a few drops of methyl orange. 



Carefully rub up the ash with a rubber-tipped stirring rod and titrate the 

 excess of acid with tenth-nornitil potassium or sodium hydroxid. Calculate 

 the alkalinity to per cent of potassium carbonate in the original substnnre. 

 One cubic centimeter of tenth-normal acid equals 0.006915 gram of potassiun, 1 

 carbonate. 



