6 



of water and evaporating over an asbestos plate, then heating at dull 

 redness. Cool in a desiccator and weigh the total ash. 

 Note the color and general appearance of the ash. 



(b) AND (c) SOLUBLE AND INSOLUBLE ASH. 



Add water to the ash in the platinum dish, heat nearly to boiling, 

 filter through ash-free filter paper, wash with hot water until the filtrate 

 and washings amount to about 60 cc. Return the filter paper and con- 

 tents to the platinum dish, carefulty ignite, and weigh. Compute per- 

 centages of water-insoluble ash and water-soluble ash. 



(d) ALKALINITY OF SOLUBLE ASH. 



Allow the filtrate from the above determinations to cool, then titrate 

 with tenth normal hydrochloric acid, using methyl orange as an indicator. 



(e) ALKALINITY OF INSOLUBLE ASH. 



Add excess of tenth normal hydrochloric acid (usually 10 to 15 cc) 

 to the ignited insoluble ash in the platinum dish, heat to the point of 

 boiling over an asbestos plate, allow to cool, and titrate excess of 

 hydrochloric acid with tenth normal sodium hydrate, using methyl 

 orange as an indicator. 



Express the alkalinity in each case as the number of cubic centime- 

 ters of tenth normal acid used on the ash of 1 gram of sample. 



(3) MANGANESE, CALCIUM, SULPHATES, AND POTASSIUM. 



Weigh 50 grams of the sample in a large platinum dish, heat over an 

 asbestos plate to the point of carbonization, carbonize at low heat, dis- 

 solve the soluble salts in hot water, filter, and wash. Return the filter 

 and residue to the dish, ignite until free from carbon, add the solution 

 of soluble salts, evaporate the whole to dryness, and gently ignite. 

 Remove the ash from the dish to a weighing bottle and keep in a desic- 

 cator. Weigh out about 0.25 gram of the dried ash, add dilute hydro- 

 chloric acid, heat gently for a few minutes, filter, wash, and make up 

 to 100 cc. 



MANGANESE (MllsOj . 



Take 50 cc of the solution, make slightly alkaline with ammonia, 

 evaporate on a water bath to remove excess of ammonia, filter, wash 

 with hot water until free from chlorids, concentrate the filtrate and 

 washings to about 50 cc, then follow the directions given in Bulletin 46, 



page 73. 



CALCIUM (CaO). 



Concentrate the filtrate from the manganese determination to about 

 50 cc, heat to 70 C., make alkaline with ammonia, add ammonium 

 oxalate in slight excess, and allow to stand over night. Filter, wash 

 thoroughly with hot water, thrust a glass rod through the apex of the 



