Boil twenty grams of the substance with water for half an hour, cool, make up to half a liter and filter. Boil fifty cubic centimeters of the filtrate, and add barium chlorid till no more precipitate forms. Mix with baryta water to strong alkaline reaction, cool, make up to 100 cubic centimeters and filter. Raise fifty cubic centimeters of the filtrate to the boiling temperature and add ammonium carbonate solution till no more precipitate forms: Cool, make up to 100 cubic centimeters and filter. Transfer fifty cubic centimeters of the filtrate to a platinum dish, evaporate and heat the residue, avoiding too high a temperature, till the ammonia salts are expelled. Dissolve the residue in water, filter, and treat the filtrate as described under A. =257. Swedish Methods.=—The Swedish chemists determine the potash in mineral salts by the platinum chlorid process, but with certain variations from the processes already given. The manipulation is conducted as follows:[206] Weigh one gram of the sample to be examined and pour about 300 cubic centimeters of hot water over it in a beaker and filter after complete solution; add one cubic centimeter of hydrochloric acid, heat nearly to boiling, add dilute barium chlorid solution from a pipette or burette in a very fine stream stirring, slowly and carefully, till all sulfuric acid is completely precipitated, and only a trace of the precipitant is in excess. If the precipitation be conducted in the way given the barium sulfate will come down in crystalline condition, and settle rapidly within a few minutes, and almost immediately after the precipitation is finished may be filtered clear. The filtrate and washings from the barium sulfate are brought into a liter flask; fill this to the mark, take out fifty cubic centimeters with a pipette, evaporate the greater portion on a water-bath in a porcelain dish, transfer the residue by means of ammonia-free water to a beaker of fifty cubic centimeters capacity, add ten cubic centimeters of platinic chlorid solution, stir well with a glass rod, evaporate on a water-bath to a sirupy condition, allow to cool, and if the residue be too dry, add a few drops of water to allow the sodium platinochlorid to take up crystal water with certainty, stir well, add alcohol after a few minutes, mix carefully, leave the mixture standing for a while in the beaker covered with a watch glass, stirring occasionally; finally decant the solution, which must be of a dark yellow color, through a very small filter, wash the precipitate in the beaker repeatedly with small quantities of alcohol and decant; then transfer the precipitate to the filter, wash with alcohol, dry the filter and the precipitate at a gentle heat till all alcohol has evaporated, carefully transfer the contents of the filter to a watch glass placed on white glazed paper; dissolve the potassium platinochlorid still remaining on the filter in small quantities of boiling water, evaporate the filtrate