DETERMINATION OF INSOLUBLE SOLIDS. 13 



DETERMINATION OF INSOLUBLE SOLIDS. 

 KREMLA'S METHOD.* 



Fifty grams of the sample are weighed, transferred to a mortar, 

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

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

 of water to stir the pulp thoroughly. Collect the filtrate in a 500 cc 

 flask, cool, and make up to volume. Usually this amount is sufficient 

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

 may be necessary to increase the washings to 1,000 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 filtrate 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, 



(1ERMAX OFFICAL METHOD. b 



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 employed to advantage with such fruits as 

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

 is made with difficulty, but care must be taken that the fruit is thor- 

 oughly macerated to insure complete solution of the soluble matter. 



DKTKI.'MINATION OF ASH. 



Kvaporate to dry ness in a large platinum dish, 50 cc of a ^0 per cent 

 solution of jelly (see p. 11, under Juices and jellies), ^5 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 with 

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

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

 orate the whole to dryncss 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 weigh. The weighing must be made 

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



"/tschr. Nahr. Hyg. Waar., 1892, 6,483. 

 b Ver. Xalir. u. (Jeimssm. f. Deutsche Reich., 2, 105. 



"McGill by letter recommends the use of a mechanical shaker to obtain complete 

 solution of the soluble materal. 



