Shake 12.25 grams of the sample in a 150 cc. bottle with 75 cc. of 95 per cent alcohol for ten minutes. Run a blank. Filter rapidly both sample and blank and wash rapidly with alcohol sufficient to make 100 cc. of filtrate. Titrate with N/20 sodium hydroxide in presence of phenolphthalein and subtract the result of titrating the blank from that of titrating the solution of the sample. The percentage of acidity, expressed as sulfuric acid (H_{2}SO_{4}), is equal to 0.02 times the number of cubic centimeters of sodium hydroxide used. SODA ASH. INSOLUBLE MATTER. Treat 5.305 grams of the sample with 200 cc. of freshly boiled and cooled distilled water. When solution is complete filter through an asbestos mat in a weighed Gooch crucible, dry, cool, and weigh. Report the weight of the residue, in percentage, as insoluble matter. AVAILABLE ALKALI. Dilute the filtrate from the determination of insoluble matter to 1,000 cc. and thoroughly mix. Titrate 25 cc. of this dilution with N/10 hydrochloric acid in presence of methyl orange indicator. The percentage of available alkali, expressed as sodium carbonate (Na_{2}CO_{3}), is equal to 4 times the number of cubic centimeters of hydrochloric acid used. CHEMICAL BIBLIOGRAPHY. The subjoined bibliography comprises the publications cited in the text of this report. The references are arranged alphabetically by authors’ names and under each author in order of dates of publication. When different pages of a single work are cited letters are used in connection with the number that refers to the work. Bibliography 1: ANDREWS, L. W. Sprengel’s method for colorimetric determination of nitrates: _J. Am. Chem. Soc._, Vol. 26, pp. 388–91, 1904. Bibliography 1a: _a._ ASSOC. OFF. AG. CHEMISTS. Determination of iodine and bromine: _J. A. O. A. C._, Vol. 1, No. 4, pt. 1, pp. 47–8, 1916. Bibliography 1b: _b._ BACHMANN, FRANK. A new seal for the prevention of aeration in deaerated liquids: _J. Ind. Eng. Chem._, Vol. 6, pp. 764–5, 1914. Bibliography 2: BARTOW, EDWARD, and RODGERS, J. S. Determination of nitrates by reduction with aluminium: _Am. J. Public Hygiene_, new ser., Vol. 5, pp. 536–44, 1909; also _Illinois Univ. Bull._, Vol. 7, No. 2 (Water Survey Ser. No. 7), pp. 14–27, 1909. Bibliography 2a: _a._ BLINN, WILLIAM. Determination of manganese as sulfate and by the sodium bismuthate method: _J. Am. Chem. Soc._, Vol. 34, pp. 1379–98, 1912. Bibliography 2b: _b._ BUSWELL, A. M. Modified apparatus for the putrescibility test: _J. Ind. Eng. Chem._, Vol. 6, p. 325, 1914. Bibliography 3: CALDWELL, G. C. A method in part for the sanitary examination of water and for the statement of results, offered for general adoption: _J. Anal. Chem._, Vol. 3, pp. 398–403, 1889. Bibliography 4: