the hands of different workers, as proved by the result of the referee and Todd. The referee's recommendation that further comparison of the Klein and United States Department of Agriculture methods for dextrose be made with a view to adopting one of them as official, should not be accepted by the association unless the alleged United States Department of Agriculture method is first made correct. REPORT ON GELATIN. By C. R. SMITH (Bureau of Chemistry, Washington, D. C.), Referee. The work on gelatin for 1918 and 1919 involved a study of its polariscopic constants and a method for the determination of sulphites. The usefulness of the polariscopic study of gelatin is indicated in the study of jelly strength and certain other applications'. The estimation of sulphite by the present association method is troublesome; the suggested method offers rapid results but needs to be tested for accuracy. Since the proportion of sulphites decreases with time, results should be obtained by the collaborator comparing the proposed diffusion method and the distillation method at the same time. In determining the optical rotation of gelatin in equilibrium at 15°C., it is very important to control the temperature carefully for accurate results. In all cases, improvised constant temperature baths were used. In view of this, the results were fairly satisfactory. POLARISCOPIC CONSTANTS OF GELATIN. Prepare concentrations of 2 and 3 grams per 100 cc. of both samples, lettered S. C. S. and T. D. T., by soaking in 40-50 cc. of cold water, heating to about 50°C. for 15 minutes and making to volume at 35°C. Polarize at 35°C. in 200 mm. tubes. Fill 100 mm. tubes of each concentration in duplicate to obtain the equilibrium rotation at 15°C. To avoid strains in the jellies, cool the solutions quickly to 10-15°C. and pour into cold dry tubes before jelly has been formed. Place the tubes in a constant temperature bath at 15°C. and leave overnight. Polarize the next day at 9 a. m., 12 m. and 4 p. m. Tabulate the results after doubling the rotations at 15°C. to place all readings on 200 mm. tube basis and using Ventszke degrees as in saccharimetry as shown in Table 1. In place of a constant temperature bath, place the tubes in a part of the ice chest registering between 12 and 16°C. overnight. Carefully control the temperature at 15°C. 0.4°C. the next day by immersion in a large volume of water maintained at 15°C. or carefully control in a dry container which is a poor conductor of heat an placed in a part of the ice chest which is near the correct temperature. 1 J. Ind. Eng. Chem., 1920, 12: 878. Assoc. Official Agr. Chemists, Methods, 1916, 150. SULPHUR DIOXID-DIFFUSION METHOD. Take 5 grams of powdered gelatin sample; add 100-150 cc. of ice water containing 3 cc. of 10% hydrochloric acid (1 to 3) and 10 grams of sodium chlorid. Gently mix and allow to stand in ice water for 2 minutes. Add starch paste of ood quality ard titrate with N/100 iodin until a blue color appears. Replace in the ice bath for 1 r.inute, remove, and titrate carefully until the color reappears. Repeat these operations until the color remains after standing for 1 minute with gentle agitation. Report the number of cc. consumed and calculate the sulphur dioxid as mg. per kilo. 1 cc. N/100 I 0.00032 gram of SO2. = If possible, check the diffusion method with the distillation method1, using a streami of inert gas and recovering the sulphur dioxid as barium sulphate. W. D. Richard--13.7 -20.2 -29.7-43.8 -29.5-44.9-29.1-44.7 2.148 2.127 son, Swift & Co., Chicago, Ill. - 43.4 -43.4 -43.6 T. R. Tennant, -13.55 -20.5-28.9-43.4 -29.0 -43.5-29.0 -43.4 2.14 2.12 United Chemi cal and Organic Products Co., Hammond, Ind. R. Hertwig, U. -15.2 -20.2-28.0 -40.4 -29.6 -44.8 -28.8-46.0 1.89 2.15 2 grams 3 grams 2 grams 3 grams 2 grams 3 grams 2 grams 3 grams 2-gram 3-gram ratio ratio W. D. Richard- -13.8 -21.1 -25.6 -39.2 -25.2 -38.7 -25.8 -39.5 1.847 1.856 -25.0 -40.0 -25.2 -38.6-26.6 -39.0 son T. R. Tennant.. -13.6-20.5 -25.8 -39.0 -26.0 -39.0 -26.0 -39.0 1.89 1.90 R. Hertwig.....-13.8-20.2 -26.0-38.8-26.1-39.3 -26.4-39.9 1.913 1.975 -26.3 -39.3 1.906 1.945 E. H. Berry.... -13.7 -20.2 -27.0-40.0 L. A. Salinger: -24.0 -36.0 1.71 October 4, 1919* -14.0 -20.65 -26.0 -41.3 -26.2 -39.7 -25.7 -37.4 1.83 1.79 1.93 * Average. TABLE 3. Determination of sulphur dioxid in Sample S. C. S. by the diffusion method. Comparison can not properly be made between the results of different collaborators made at different times. The result of Salinger was obtained last and shows that over half of the sulphur dioxid had disappeared. Richardson reported the sulphur dioxid on a good grade of glue as 4440, 4141, 4347 and 4231 mg. per kilo as compared with 3212, 3212, 3166 and 3102 mg. by the diffusion method. COMMENTS. Hertwig reports that the polariscope he used for the 35°C. readings did not read farther than -20°V. He estimated the 35°C. readings given for the 3-gram concentrations as probable values. Salinger reports that warm, humid weather made readings difficult. Richardson had no suitable cooler to maintain the required tempera ture. Berry reports irregularity in ice chest temperature during the night and difficulty in making readings at the lower temperature. REPORT ON EDIBLE FATS AND OILS. By R. H. KERR (Bureau of Animal Industry, Washington, D. C.), Referee. The work has consisted of the examination and criticism of the report of the Committee on Fats and Oils of the American Chemical Society1. This committee has recommended a set of uniform methods for the sampling and analysis of fats and oils to be used by members of the American Chemical Society. The report shows divergence in some respects from the methods adopted by this association but appears unlikely to lead to any actual inconvenience or confusion except in one respect. This is in the method proposed for the determination of the iodin number. The committee has adopted the Wijs method for the determination of the iodin number1 instead of the well-tried Hanus method2, now official in this association and in the American Society for Testing Materials. The committee appears to consider that the Wijs method has certain advantages which make its adoption advisable, even at the cost of causing the confusion which will inevitably result from the use of two methods which do not always give identical results by the different societies. In the opinion of your referee, the advantages of the Wijs method are not substantial and the adoption of the Hanus method by this association was justified in the light of present information as well as information available at the time of its adoption, and such advantages as are possessed by the Wijs method are more than overbalanced by the disadvantages of having two different official methods. Since, however, the Wijs method has been definitely adopted by the Fats and Oils Committee and will be official in the American Chemical Society, this condition of confusion must inevitably occur and can not be prevented by this association. The following recommendations are offered for the purpose of reducing this confusion as much as possible: RECOMMENDATIONS. It is recommended (1) That the Hübl method for the determination of the iodin number3 be dropped from the official methods. (2) That the use of the Wijs method, as adopted by the American Chemical Society, be made optional under the official methods. (3) That all reports of iodin numbers specify the method used and where no method is specified it shall be understood that the determination was made by the Hanus method. REPORT ON SPICES. By H. E. SINDALL1 2 (Austin, Nichols & Co., Inc., New York, N. Y.), Referee on Spices and Other Condiments. The work has been a continuation of the study of the referee's modification of the distillation method for water in whole spices and the tentative method for the determination of volatile oil in mustard seed3. MOISTURE IN PEPPER AND CLOVES. Samples of Zanzibar cloves and Lampong pepper were sent to six collaborators, with a copy of the method, a photograph of the apparatus used by the referee, and instructions to follow the method as written and to determine the moisture also by the official method. Reports were received from three collaborators: M. B. Porch, H. J. Heinz Co., Pittsburgh, Pa.; W. B. Smith, Armour & Co., Kansas City, Kans.; and F. M. Boyles, McCormick & Co., Inc., Baltimore, Md. The following method was sent: Place 50 grams of whole spice in a distillation flask with 150 cc. of kerosene; whirl the flask several times to bring the oil in contact with each particle of spice. Place the flask on an asbestos board, cut so that the bottom of the flask extends below the surface. Place a wire gauze with an asbestos center about inch below the bottom of the flask. The object is t keep the flame from direct contact with the flask. The asbestos board serves to keep the heat uniform. Connect the flask directly with the vertical condenser. Insert a thermometer through the stopper of the distillation flask extending into the cil. Adjust the flame so that about 20 minutes will be required to reach the temperature of 170°C., and collect the distillate in a graduated cylinder or burette. Extinguish the flame, after which the thermometer will show a slight gradual increase in temperature. As soon as the water stops dropping from the condenser tube, which usually requires 4-6 minutes, the operation is complete. Multiply the volume of the water layer by 2 to obtain the percentage of moisture. The results obtained are shown in Table 1. 1 Presented by L. C. Mitchell. 2 Present address, Francis H. Leggett & Company, New York, N. Y. J. Assoc. Official Agr. Chemists, 1920, 4: 149. Assoc. Official Agr. Chemists, Methods, 1916, 79. |