. Bulletin - Massachusetts Agricultural Experiment Station. Agriculture. IMPROVED METHODS FOR FAT ANALYSIS. 107 fication is complete, — about sixty mirxutes. The condenser is then re- moved and the flask placed in a water bath (immersed in the water) and the alcohol evaporated at a gradually increasing temperature, care being taken to prevent spattering. The last traces of alcohol, occluded in the soap, are expelled by breaking up the dry cake or by dissolving it in water and continuing the heating. Water to a volume of 100 cubic centimeters and 1 cubic centimeter of N/2 sulfui'ic acid in exce
. Bulletin - Massachusetts Agricultural Experiment Station. Agriculture. IMPROVED METHODS FOR FAT ANALYSIS. 107 fication is complete, — about sixty mirxutes. The condenser is then re- moved and the flask placed in a water bath (immersed in the water) and the alcohol evaporated at a gradually increasing temperature, care being taken to prevent spattering. The last traces of alcohol, occluded in the soap, are expelled by breaking up the dry cake or by dissolving it in water and continuing the heating. Water to a volume of 100 cubic centimeters and 1 cubic centimeter of N/2 sulfui'ic acid in excess of that required to neutralize the 50 cubic centimeters of alcoholic potash are added, and the flask, connected with a spiral condenser, heated on a water bath until the separated fatty acids and underlying liquid become clear. From this point the process is conducted the same as for insoluble acids, using a spiral condenser to prevent loss of volatile acids. The combined filtrate and washings are titrated with N/2 potassium hydroxide, using phenol- phthalein as indicator. The difference between the titration of the test and that of the excess N/2 acid (1 cubic centimeter) is the alkali equivalent of the soluble acids in the fat taken, which should be calculated to milli- grams of potassium hydroxide for 1 gram of fat. 1 cubic centimeter of N/2 alkali is equivalent to milUgrams of potassium hydroxide. The percentage of soluble fatty acids (S) is calculated from the number of milligrams of potassium hydroxide (k) required to neutralize the solu- ble acids in 1 gram of fat and the determined (or estimated) neutraliza- tion number (n) of the soluble acids by the formula — S = ^ Limit of error, per cent. Supplementary Notes. — The solubility of acids of the acetic series de- creases with the increase in number of carbon atoms in the molecule. The so-called "soluble" acids include capric and all acids of less carbon atoms. Acid. Soluble in lOO Parts of
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