Report on Foods and Feeding Stuffs. By G. L. Bidwell.. Densimetric and Polariscopic Standardization in Reference to the Associate Referee's Report 321 321 330 The Attitude of the New York Sugar Trade upon the New Bureau of Standards Value for 334 Comments on Recommendations Proposed by A. H. Bryan. By W. D. Horne. 335 A Suggested Modification of the Method for Crude Fiber. By L. D. Haigh. 336 Report on Stock Feed Adulteration. By B. H. Silberberg. 340 Report on Water in Foods and Feeding Stuffs. By J. O. Clarke. 344 The Determination of Water in Cereal and Meat Products. By F. C. Cook. 347 351 Methods for Estimating Limits of Chlorids in Chemicals. By L. F. Kebler and W. H. Heath.. 360 MONDAY AFTERNOON SESSION. Report on Nitrogen. By I. K. Phelps. 365 Report on Special Study of the Kjeldahl Method. By H. W. Daudt. 366 373 The Effect of Manure-sulphur Composts upon the Solubility of the Potassium of Greensand. 375 A Comparison of Results Obtained by the De Roode, Official Lindo-Gladding and Former Report on the Lime Absorption Coefficient of Soils. By W. H. MacIntire 389 391 Report on Insecticides and Fungicides. By O. B. Winter. 395 The Solubility of Calcium and Magnesium Arsenates in Carbon Dioxid and Its Relation to 404 The Determination of Water-soluble Arsenic Oxid in Calcium Arsenate. By J. J. T. Graham.. 406 The Turner Reaction for Gurjun Balsam. By J. B. Luther. 422 Recommendations by the Associate Referee on Enzyms. By F. J. Brewster. 425 The Pharmacopoeial Assay for Alcohols in Santal Oil Extended to Include the True Acetyl 425 TUESDAY-MORNING SESSION. Report on Maple Products. By J. F. Snell.. The Determination of Ash in Cane Sirups and Molasses. By F. W. Zerban. Report on Metals in Foods. By W. D. Collins. Physico-chemical Methods for Determining the Grade of Flour. By C. H. Bailey PUBLISHED QUARTERLY BY THE ASSOCIATION OF OFFICIAL AGRICULTURAL CHEMISTS WASHINGTON, D. C. 428 444 452 454 456 459 INFORMATION FOR SUBSCRIBERS AND CONTRIBUTORS. THE JOURNAL OF THE ASSOCIATION OF OFFICIAL AGRICULTURAL CHEMISTS is issued quarterly. Each volume will contain approximately 600 pages. Subscriptions are taken by the volume and not by the year. Reprints of articles will be furnished to contributors at cost when ordered in advance. A table showing cost, with an order slip, is sent with proof. Manuscripts should be typewritten and carefully revised before submission and should be sent to the Association of Official Agricultural Chemists, Box 744, Eleventh Street Station, Washington, D. C. Subscription Price: North America and U. S. possessions, $5.00 a volume net, postpaid; all other countries, $5.50 (27s) net, postpaid. Claims for copies lost in the mails will not be allowed unless received within thirty days (domestic) of the date of issue; sixty days (foreign). Claimants must state that the publication was not delivered at their recorded address. Notice of change of address must be forwarded at least one week in advance of issue; otherwise publishers will not be responsible for loss. Address all correspondence to the Association of Official Agricultural Chemists, Box 744, Eleventh Street Station, Washington, D. C. FIRST DAY. MONDAY-MORNING SESSION. The thirty-fifth annual convention of the Association of Official Agricultural Chemists was called to order by the President, P. F. Trowbridge, of Agricultural College, North Dakota, on the morning of November 17, 1919, at 10:00 at the New Willard, Washington, D. C. REPORT ON FOODS AND FEEDING STUFFS. By G. L. BIDWELL (Bureau of Chemistry, Washington, D. C.), Referee. The referee has very little to report. He has consulted with his associate referees on several occasions, written letters regarding the work of the association, and given advice to a small extent. The investigational work, however, has been conducted by the associate referees and their reports will speak for themselves. R. F. Jackson and C. L. Gillis (Bureau of Standards, Washington, D. C.) presented a paper on "The Double-Polarization Method for Estimation of Sucrose and the Evaluation of the Clerget Divisor"1. REPORT ON SUGAR. By A. H. BRYAN2 (Arbuckle Bros., New York, N. Y.), Associate Referee. DISCUSSION OF FORMER ASSOCIATE REFEREE'S RECOMMENDATIONS. During the past two years it has been impossible for the associate referee to carry on any extended work upon the recommendations left over from the 1916 meeting, although many of these are of the greatest importance to chemists called upon for sugar determinations. The recommendations of C. A. Browne (New York Sugar Trade Laboratory, 80 South Street, New York, N. Y.), former associate referee, called for further study along the following lines3: (1) Upon the modifications proposed in 1916 for determining sucrose by acid and invertase inversion. (2) Upon methods for the determination of small amounts of reducing sugars in the presence of sucrose. (3) Upon the methods of determining copper by reduction of the oxid in alcoholic vapors. (4) Upon the optical methods for estimating raffinose in beet products, using enzyms for the hydrolysis. It is suggested that the first, second, and fourth recommendations be referred to the Carbohydrate Laboratory of the Bureau of Chemistry for study, as there is need in these recommendations for the continuous work of one man. The third recommendation could be studied by any chemist doing reducing sugar determinations, as it is a rapid method of determining the copper in the cuprous oxid precipitate from reducing sugar determinations. In the case of pure sugars, the weighing of the cuprous oxid gives good results, but with impure sugar products this method does not give true results, because of the contamination of the cuprous oxid with organic matter, and also with mineral salts. The changing of the cuprous oxid to cupric oxid by heating, or of the cuprous oxid to copper by alcoholic vapors, removes the organic matter, but does not remove the contamination by mineral salts. The most accurate method is to determine the copper in the precipitate volumetrically. At the 1916 meeting, W. D. Horne (National Sugar Refining Company, Yonkers, N. Y.) asked for an investigation and report upon five points1. Upon some of these a little work has been conducted, but on others there seems to be no particular need for experimentation. The following suggestions on the points submitted by Horne are made: (1) That raw sugar samples be mixed in a mortar, instead of on a plate, to diminish moisture changes.-Under normal conditions there is little moisture change by mixing samples of raw sugar on a glass plate, and a more thorough mixing in a shorter time is accomplished on the glass plate than in the mortar. It was impossible for the associate referee to mix as many samples in a given length of time in a mortar as upon a glass plate. This, however, may have been due to awkwardness on his part, as he has always used the glass-plate method. Comparative experiments showed a greater tendency for wet sugars to cling to the mortar than to the glass plate, and more difficulty was noted in cleaning the mortar than the glass plate. With certain raw sugars, as Philippine mats and hard, lumpy, dry sugar, the mortar gave a sample more even in appearance than the same sample mixed upon a glass plate, using a rolling pin or spatula to mash the lumps. Polarization, however, revealed no decided difference in favor of the one or the other method of mixing. It 1 J. Assoc. Official Agr. Chemists, 1919, 3: 263. |