Acidify the solution of soluble ash, obtained in 9, with dilute nitric acid and determine phosphoric acid (P_2_O_5). For percentages up to 5 use an aliquot corresponding to 0.4 gram of substance, for percentages between 5 and 20 use an aliquot corresponding to 0.2 gram of substance, and for percentages above 20 use an aliquot corresponding to 0.1 gram of substance. Dilute to 75-100 cc., heat in a water-bath to 60 deg.-65 deg. C., and for percentages below 5 add 20-25 cc. of freshly filtered molybdate solution. For percentages between 5 and 20 add 30-35 cc. of molybdate solution. For percentages greater than 20 add sufficient molybdate solution to insure complete precipitation. Stir, let stand in the bath for about 15 minutes, filter _at once_, wash once or twice with water by decantation, using 25-30 cc. each time, agitate the precipitate thoroughly and allow to settle; transfer to the filter and wash with cold water until the filtrate from two fillings of the filter yields a pink color upon the addition of phenolphthalein and one drop of the standard alkali. Transfer the precipitate and filter to the beaker, or precipitating vessel, dissolve the precipitate in a small excess of the standard alkali, add a few drops of phenolphthalein solution, and titrate with the standard acid. 12. _Insoluble Phosphoric Acid in the Ash--Official_ Determine phosphoric acid (P_2_O_5) in the Insoluble ash by the foregoing method. 13. _Chlorides--Official_ Moisten 5 grams of the substance in a platinum dish with 20 cc. of a 5-percent solution of sodium carbonate, evaporate to dryness and ignite as thoroughly as possible at a temperature not exceeding dull redness. Extract with hot water, filter and wash. Return the residue to the platinum dish and ignite to an ash; dissolve in nitric acid, and add this solution to the water extract. Add a known volume of N/10 silver nitrate in slight excess to the combined solutions. Stir well, filter and wash the silver chloride precipitate thoroughly. To the filtrate and washings add 5 cc. of a saturated solution of ferric alum and a few cc. of nitric acid. Titrate the excess silver with N/10 ammonium or potassium thiocyanate until a permanent light brown color appears. Calculate the amount of chlorin. 14. _Caffein--The Fendler and Stueber Method--Tentative_