Report of the Committee on Editing Tentative and Offical Methods of Analysis, the Association of Official Agricultural Chemists . approximately 10% solution of mercuric nitrate,and heat for 5-10 minutes on the water bath. In the presence of sucrol a violet bluecolor is formed, which is changed to a deep violet on the addition of lead peroxid. FORMIC ACID. Quantitative Method.^^ 38 REAGENTS. (a) Sodium acetate solution.—Dissolve 50 grams of dry sodium acetate in suffi-cient water to make 100 cc. and filter. (b) Mercuric chlorid reagent.—Dissolve 100 grams of mercuric chlorid and 150grams of sod
Report of the Committee on Editing Tentative and Offical Methods of Analysis, the Association of Official Agricultural Chemists . approximately 10% solution of mercuric nitrate,and heat for 5-10 minutes on the water bath. In the presence of sucrol a violet bluecolor is formed, which is changed to a deep violet on the addition of lead peroxid. FORMIC ACID. Quantitative Method.^^ 38 REAGENTS. (a) Sodium acetate solution.—Dissolve 50 grams of dry sodium acetate in suffi-cient water to make 100 cc. and filter. (b) Mercuric chlorid reagent.—Dissolve 100 grams of mercuric chlorid and 150grams of sodium chlorid in sufficient water to make 1 liter and filter. (C) Tartaric acid. (d) Barium carbonate. 39 APPARATUS. The apparatus required (Fig. 6) consists of a steam generator (S), a 300 cc. flask(A) in which the sample is placed, a 500 cc. flask (5), containing a suspension of bari-um carbonate, a spray trap (T), a condenser, and a 1 liter graduated flask (C).The tip of the tube (D), leading into (B), consists of a bulb containing a numberof small holes to break the vapor into small bubbles. X] FOOD PRESERVATIVES 153. FIG. 6. APPARATUS FOR DETECTION OF FORMIC ACID. 40 DETERMINATION. For thin liquids like fruit juices, use 50 cc. For heavy liquids and semi-solidslike sirups and jams, use 50 grams diluted with 50 cc. of water. Place the sam-ple in the flask (A), add 1 gram of tartaric acid, and connect as shown in Fig. 6,the flask (B) having been charged previously with a suspension of 2 grams of bariumcarbonate in 100 cc. of water. If much acetic acid is present, sufficient bariumcarbonate must be used so that at least 1 gram remains at the end of the the contents of flasks (A) and (B) to boiling and distil with steam from thegenerator (S), the vapor passing first through the sample in flask (A), then throughthe boiling suspension of barium carbonate in (B), after which it is condensed, andmeasured in the graduated flask (C). Continue the distillation until
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