532 NEW YOEK STATE MUSEUM 



In case manganese is present, the' filtrate fromi the silica is neu- 

 tralized as closely as possible, sodium acetate solution added, the 

 solution diluted largely, and boiled for about a minute and filtered 

 as rapidly as possible, the precipitajte washed with boiling water, 

 redissolved in dilute hydrochloric acid and reprecipitated in the 

 same way, washed, ignited and weighed as re^Og and AlgOg. 

 The combined filtrates from the iron and alumina are evaporated 

 to about 300 cc, bromin water added and the solution boiled, when 

 the manganese is precipitated as MnO . This is filtered out, dis- 

 solved in a little dilute hydrochloric acid, a solution of microcosmic 

 salt added, the solution heated toi boiling and then ammonia added 

 to exact neutrality, any excess of ammonia being removed by heat- 

 ing on the water bath. The precipitate of manganese ammonium 

 phosphate is filtered out, ignited and weighed as MuaPaO?- The 

 filtrate from the mauganese precipitation is acidified with hydro- 

 chloric acid, boiled for a short time, and then treated in the same 

 way as when manganese was absent, for the determination of lime 

 and magTiesia. 



For the determination of alkalis one grain of clay is mixed by 

 grinding in an agate mortar with one grain of granular ammonium 

 chlorid and eight grains of pure calcium carbonate, the mixture 

 transferred tO' a platinum crucible with a well fitting lid and slowly 

 heated to decompose the ammonium chlorid, then heated to' redness 

 and the bottom of the crucible kept at a bright red for about an 

 hour. The contents of the crucible are transferred tO' a porcelain 

 casserole with about 80cc of water and heated toi boiling; this is 

 then filtered and to the filtrate, after evaporation to small bulk, 

 about one and one half grams of pure ammonium carbonate is added 

 and the solution heated nearly to boiling and filtered into a platinum 

 dish, evaporated nearly to dryness, a little more ammonium carbonate 

 added and the evaporation finished on the water bath. If the last 

 addition of ammonium carbonate produced a precipitate, the residue 

 in the dish is dissolved in a little water and filtered into another 

 platinum dish, where it is evaporated into dryness and ammonia 



