(3) _Potassium Sulfate, Kainit, Etc._—In the analysis of kainit, dissolve ten grams of the pulverized salt in 300 cubic centimeters of boiling water, add ammonia to slight excess, then a sufficient quantity of ammonium oxalate to throw down all lime present; cool and make up to half a liter, mix thoroughly, and filter on a dry filter; from twenty-five cubic centimeters, corresponding to a half gram, proceed to remove the ammonia, as in the analysis of superphosphates; dissolve the residue in hot water, plus a few drops of hydrochloric acid, and add fifteen cubic centimeters of platinum solution. In the analysis of high-grade sulfate and of double-manure salt (potassium sulfate, magnesium sulfate, containing about twenty-seven per cent of potassium oxid), make up the solution as above, but omit the precipitation, evaporation, etc.; to an aliquot part equal to a half gram add fifteen cubic centimeters of platinum solution. In all cases special care must be taken in the washing with alcohol to remove all the double platinum sodium chlorid which may be present. The washing should be continued some time after the filtrate is colorless. Twenty-five cubic centimeters of the ammonium chlorid solution are employed instead of ten cubic centimeters, and the twenty-five cubic centimeters poured through at least six times to remove all sulfates and chlorids. Wash finally with alcohol; dry and weigh as usual. =252. Alternate Method for Potash.=—Boil ten grams of the prepared sample for thirty minutes with 300 cubic centimeters of water, and, after cooling and without filtering, make up to one liter and filter through a dry filter. If the sample have ten per cent of potassium oxid, use fifty cubic centimeters of the filtrate; if less than ten per cent of potassium oxid (ordinary potash fertilizers), use 100 cubic centimeters of the filtrate. In each case make the volume up to 150 cubic centimeters, heat to 100°, and add, drop by drop with constant stirring, a slight excess of barium chlorid, and, without filtering, in the same manner add barium hydrate in slight excess. Filter while hot and wash until the precipitate is free of chlorids. Add to the filtrate one cubic centimeter of strong ammonium hydrate, and then a saturated solution of ammonium carbonate, until the excess of barium is precipitated. Heat and add, in fine powder, a half gram of pure oxalic acid or 0.75 gram of ammonium oxalate. Filter, wash free of chlorids, evaporate the filtrate to dryness in a platinum dish, and ignite carefully over the free flame, below red heat, until all volatile matter is driven off.