BULLETIN No. 90a. 
13 
is precipitated. Heat, add now, in fine powder, 0.5 grams pure oxalic 
acid. Filter, wash free of chlorides; evaporate the filtrate to dry¬ 
ness in a platinum dish, ignite carefully over a free flame below red 
heat until all volatile matter is driven off. Digest the residue with 
hot water with a few drops of HC1, filter through a small filter, 
wash, evaporate filtrate to dryness in a tared platinum dish. Ignite 
gently at low red heat, and weigh as total alkalies. 
Potash .—The residue from the above is taken up with a few drops 
of HC1 and hot water; enough platinic chloride is added to precipi¬ 
tate the chlorides; evaporate until the solution erystalizes upon 
cooling, treat with 80 per cent, alcohol, wash by decantation, collect 
in a Gooch crucible, wash with strong alcohol, dry at 100° for thirty 
minutes, and weigh as K 2 Pt Clo. 
Soda .—Soda is determined by difference between potash and total 
alkalies. 
Lime .—Fifty cubic centimeters of the original solution are made 
alkaline with ammonia, then acetic acid is added in excess; filter 
and wash thoroughly. The filtrate is heated nearly to boiling, and 
ammonia oxalate added in slight excess; continue to heat until the 
supernated liquid is clear; filter, wash, dry, ignite intensely, and 
weigh as CaO. 
Magnesia .—The last filtrate is made alkaline with ammonia, sodium 
phosphate added, and allowed to stand for some time; filter, wash 
with weak ammonia, dry, ignite, and weigh as Mg 2 P 2 07 . 
Phosphoric acid .—Take 50 c. c. of the original solution, neutralize 
with ammonia, then make slightly acid with nitric acid, add 50 c. c. 
(more if necessary) molybdic solution, and keep for one hour at the 
temperature of 65° C. Filter, and wash with ammonium nitrate 
solution. This filtrate is used for the determination of iron and 
alumina, described in the next paragraph. The precipitate is dis¬ 
solved on the filter with dilute ammonia and hot water; the filtrate 
is nearly neutralized with HCl,and 10 c. c. magnesia mixture is added 
slowly, with constant stirring; after fifteen minutes add 25 c. c. strong 
ammonia, and let stand for 2 hours or more; filter, wash with dilute 
ammonia, ignite, and weigh as Mg 2 P 2 07 . 
Iron and alumina. —The filtrate from the precipitate of ammo¬ 
nium phospho-molybdate is cautiously neutralized with ammonia, 
care being taken that the temperature does not rise above 40° C., and 
that the ammonia is only in slight excess. Allow to stand in a 
warm place until the precipitate completely settles; filter the super¬ 
natant liquid, wash the precipitate by decantation, then transfer it to 
a filter and complete the washing. Kedissolve the precipitate in 
weak nitric acid, reprecipitate, filter, wash, dry, ignite, and weigh as 
ferric oxide and alumina. 
Ferric Oxide .—Dissolve the precipitate of ferric oxide and alumina, 
reduce with zinc, and determine the ferric oxide with a standard 
solution of potassium permanganate. 
