The Students' Guide in Quantitative Analysis - Free Ebooks Library

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APPENDIX.
ALTERNATE METHOD,
Pulverize the ferlilizer 1200 or 300 grams) in a mortar ; take 10
prams, boil for ten minutes with 200 cc. water, and after cooling, and
without filtering, make up to i.ooo cc, and filter througii a dry paper.
In tills method, in cade the potash is contained in organic compounds,
like tobacco stems, cottonseed hulls, &c., the substance is to be
saturated with strong sulphuric acid and ignited in a muffle to destroy
organic matter, [f the sample have 10 to 15 per cent K,0
(kaiiiitc), take 50 cc. of tlic tiltrate ; if from 2 to 3 per cent K5O (ordi-
nary potash fertilizers), lake 100 cc. of the filtrate, In eacli case
maKc the volume up to 150 cc, heat to too', and add, drop by drop,
with constant stirring, slight e.Kcess of bariuni chloride; without
filtering, in the same manner, add barium hydrate in slight excess
Meat, filter, and wash until preci]iitate is free of chlorides. .Add 10
filtrate i cc. strong ammonium liydrate, and then a saturated soiu.ion
of ammonium carbonate until excess of barium is precipitated. Heat.
Add now, in line powder, o.J gram pure oxalic acitl or 0,75 gram
ammonium oxalate. Filter, wash free of chlorides, evaporate filtrate
to dryne-ss in a platinum dish, and, holding- di.sh witii crucibie longs,
ignite carefully over the free flame below red heat until all volatile
matter is driven off.
The residue is now digested with hot water, filtered through a.
small filter, and washed with successive small portions of water until
the filtrate amounts to 30 cc. or more. To this filtrate, after adding
two drops of strong hydrochloric acid, is added, in a porcelain dish. 5
to 10 cc. of a solution of to grams of platinic chloride in loo cc. of
water. The mixture is now evaporated on the water-bath to a thick
syrup, or further treated with strong alcohol washed by decantation.
collected in a Gooch crucible or other form offdter, washed with
strong alcohol, afterwards with 5 cc. ether, dried for thirty minutes
at 100' C, and weighed.
It IS desirable, if there is an appearance of white foreign matter in
the double sail, that it should be washed, according to the previous
method, with to cc. of the half-concentrated solution of NH.Cl, which
has been saturated by shaking with K.PtCU. as recommended by
Gladding.
The use of the factor 0.3056 lor converting K.PtCU to KCI and
0.19308 for converting to K,0 is continued.