DETEKMINATION OF INSOLUBLE SOLIDS. 13 



DETERMINATION OF INSOLUBLE SOLIDS. 



kremla's method.^ 



Fift}' grams of the sample are weighed, transferred to a mortar, 

 and thoroughly triturated. The mass in then transferred to a muslin 

 tilter and washed wnth warm water, care being taken at each addition 

 of water to stir the pulp thoroughl\\ Collect the filtrate in a 50U cc 

 flask, cool, and make up to v^olume. Usualh" this amount is sufficient 

 to completely remove all soluble material; in some cases, however, it 

 ma}^ be necessar}^ to increase the washings to 1,0U0 cc. The insoluble 

 residue is transferred to a tared dish, the excess of water is evaporated, 

 and the residue dried in a water oven at 100'^ C. for four hours before 

 weighing. The tiltrate may be slightly turbid, showing that some of 

 the insoluble matter has passed through the filter, but this amount will 

 be inappreciable. Kremla used cold water and coarse filter paper, and 

 the method has been modified in this work in these respects^ 



GERMAN OFFICAL METHOD.'' 



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

 add water, shake thoroughly, and make up to volume. "^ Allow this to 

 settle and either filter or decant off the supernatant liquid. Take an 

 aliquot portion for the determination of soluble solids. Total solids 

 less the soluble solids equals the insoluble solids. 



This method may be emplo3^ed to advantage with such fruits as 

 cherries and small fruits, with which even the filtration through nmslin 

 is made w4th difl^cult}^, but care must be taken that the fruit is thor- 

 oughly macerated to insure complete solution of the soluble matter. 



DETERMINATION OF ASH. 



Evaporate to dryness in a large platinum dish, 50 cc of a 2U \wv cent 

 solution of jelly (see p. 11, under Juices and jellies), 25 grams of juice 

 or fresh fruit, or 10 grams of jam, marmalade, preserve, or canned 

 fruit; then thoroughly char at as low a heat as possible, extract wnth 

 water, filter, and wash. Return the filter paper and insoluble material 

 to the dish and thoroughlv ignite; add the soluble portion and evap- 

 orate the whole to dryness after adding a few cubic centimeters of a 

 solution of ammonium carbonate; then heat for a moment to very low- 

 redness; cool in a desiccator and w^eigh. The weighing nuist be made 

 as quickly as possible, as the ash absorbs moisture very rapidly. 



"^Ztschr. Nahr. Hyg. Waar., 1892, 6, 483. 

 ^Ver. Nahr. u. Genussm. f. Deutsche Reich., 2, 105. 



■^McGill by letter recommends the use of a mechanical shaker tt) obtain complete 

 solution of the soluble materal. 



