_Manipulation._—Twenty-five or fifty cubic centimeters of a solution of the phosphate which has been made up to a standard volume and containing about one-tenth gram of phosphorus pentoxid, are placed in a beaker together with 100 cubic centimeters of the molybdate solution and treated with as much ammonium nitrate solution as will be sufficient to give the liquid a content of fifteen per cent of ammonium nitrate. The contents of the beaker are well mixed and warmed for about twenty minutes at from 60° to 80°. After cooling, they are filtered and the precipitate washed on the filter with cold water until a drop of the filtrate saturated with ammonia does not become opaque on treatment with ammonium oxalate. The filtrate is then washed from the filter with two and one-half per cent ammonia solution and precipitated slowly and with constant stirring by the magnesia mixture. After standing for two hours the ammonium magnesium phosphate is separated by filtration, washed with two and one-half per cent ammonia until the filtrate contains no more chlorin, and ignited. _Conduct of the Citrate Method._—The principle of this method depends upon the fact that when a sufficient quantity of ammonium citrate is added to phosphate solutions, iron, alumina, and lime are retained in solution when, on the addition of the magnesia mixture in the presence of free ammonia, the phosphoric acid is completely precipitated as ammonium magnesium phosphate. _Manipulation._—From ten to fifty cubic centimeters of the solution of the phosphate to be determined are treated with fifteen cubic centimeters of the Joulie citrate solution avoiding warming. A few pieces of filter-paper, the ash content of which is known, are thrown in and, with stirring, fifteen cubic centimeters of magnesia mixture slowly added and if necessary also some free ammonia. By the small pieces of filter-paper the collection of the precipitate against the sides of the vessel and on the stirring rod is prevented and in this way the production of the precipitate hastened. After standing from one-half an hour to two hours the mixture is filtered, ignited, and weighed. If it be preferred to estimate the phosphoric acid by titration, the precipitate is dissolved in a little nitric acid, made slightly alkaline with ammonia, and then acid with acetic and then afterwards titrated with the standard uranium solution. _Conduct of the Uranium Method._—The principle upon which this method rests depends upon the fact that uranium nitrate or acetate precipitates uranium phosphate from solutions containing phosphoric acid and which contain no other free acid except acetic. In the presence of ammonium salts the precipitate is uranium ammonium phosphate having the formula PO₄NH₄UrO₂. The smallest excess of soluble uranium salt is at once detected by the ordinary treatment with potassium ferrocyanid.