【導讀】近年來，一些有關(guān)快速皂化和甘油測定委員會的活動證明了這一點。皂化，Ⅱ、，Ⅲ、卡芮士試管法，Ⅳ、催化法，蒸餾水的重約4克的樣本，還要把這種混合物回流85分鐘。加入熱水后，放入蒸。數(shù)值得那部分中加入重鉻酸鉀溶液和濃硫酸，加熱15分鐘后冷卻。動物油被列入易皂化行列而棉籽油和氫化棉籽。的，而它的成功原因在于機械的攪拌引起的充分混合。乳化劑和腐蝕劑無效?？鞠渲屑訜嵋灰梗弥劂t酸鉀氧化；過量的用硫代硫酸鈉滴定，有淀粉作指示劑。際上是建議實驗室在皂化時用乳化劑。達到令人滿意的效果所需條件和硬脂酸及50％的氫氧化鉀的量回有所不同。些穩(wěn)定的棉子油類被稱為A類油脂。的乳化劑，數(shù)據(jù)列在表Ⅳ中。在此基礎(chǔ)上和類似的試驗證明，把4㏄50％的氫氧化鉀溶液定為標準。觀察發(fā)現(xiàn)4％的量可以產(chǎn)生及好的較大量的乳化劑，所以這個量就被視為標準。從這些數(shù)據(jù)來看，20分鐘時限是完全皂化的最佳時間。最初這種加熱是在一個熱盤上進行的。

　　

【正文】 lation of the results obtained by the various methods is given in Table X. The results given under Committee Thiosulphate are those ob, tained by saponification according to the method proposed by the Committee and the glycerol determined by the thiosulphate method while those under Committee are determined by the entire method as proposed by the Committee. The results of the latter are in better agreement with the theoretical than the former. A survey of the results reveals that no one of these methods is greatly superior to the others with respect to accuracy, it being possible in most cases to ascribe the variation to the limits of error for the method. The results obtained by the Carius Method are slightly higher than those of the other methods, which may or may not be significant The method involving the use of catalysts, either stearic acid or bentonite is simple, rapid and apparently as reliable as the other methmittee ods discussed. Stearic acid gives a clear solution when the oils are sa ponified which is not true for bentonite. Bentonite has the advantage that the initial temperature of theoil need be no higher than 100 176。C.,so that instead of heating the flask containing the oil in an oil bath at 160 176。C., it may be heated in the same 105 176。C. oven where the saponification is pleted. If a 105 176。C. oven is not available, the heating preliminary to and during saponification may be done by partially immersing the flask containing the fat in boiling water. The advantage of the catalytic method of saponification is the fact that the time is greatly reduced. The time required for this method is only 20 minutes as pared with at least an hour and a half for the methmittee method and Overnight for the Carius method. Judging from the results given in Table X, the percentages of glycerol obtainable from fats may be determined to a fair degree of accuracy in the shortest time by the catalytic method of saponification and the potassium dichromate and sodium thiosulphate method of oxidation and titration. However, a higher degree of precision may possibly be attained with somewhat increased time by saponifying by the catalytic method, oxidizing with potassium dichromate and titrating with ferrous ammonium sulphate. Further work is being undertaken to apply the use of diphenylamine 8 as an indicator in ,the titration of the excess potassium dichromate with ferrous ammonium sulphate and to determine the applicability of eleetrometric titrations to this analysis. Both of these methods hold promise of success and may add to the accuracy of the method as well as a reduction of time for the analysis. Procedure for the Proposed Catalytic Method A sample of fat, 4 177。 grams,is accurately weighed in a 100 flask on an analytical balance. Roughly grams of stearic acid or to grams of bentonite are added ( grams for tallow and coconut oil, grams for hydrogenated cottonseed oil and grams for cottonseed oil). The stearic acid is conveniently added by dropping from a roughly calibrated dropper. The fat containing the stearic acid is heated to 140150 176。 C. for hydrogenated cottonseed oil and cottonseed oil and to 110120 176。 C. for tallow and coconut oil by immersing in an oil bath at 160165 176。 C. for 3 minutes. If bentonite is used, the fats are heated to 100 176。 C. in a water bath or 105 176。C. oven. The flask is rotated and shaken to distribute the catalyst uniformly in the fat. Then, 4 cc. of 50% aqueous potassium hydroxide is slowly added with shaking and the mixture vigorously agitated with rotary motion for 30 seconds. The flask is loosely stoppered and placed in the 105176。 C. oven. After 20 minutes it is removed, the soap is dissolved and the solution is cleared, oxidized and the excess oxidant titrated. SUMMARY Several methods of saponification of fats for the determination of available glycerol are considered. 1. The Direct Saponification Method? 2. A Method proposed by the . Committee on Glycerine Determination. 3. The Carius Method. 4. A Method for Rapid Saponification of fats and oils is proposed for laboratory use in determining glycerine yields in which stearin acid or bemonite is added as a catalyst. Upon the addition of potassium hydroxide and vigorous shaking, a fine emulsior~ is formed provided the proper conditions are regarded. The saponification takes place in a 105 o C. oven and is pleted in 20 minutes. The proposed method has the followingadvantages : saponification is pleted in 20 minutes. 2. No special apparatus is required. 3. Saponification takes place at the paratively low temperature of 100 to 105 176。C. 4. The method is simple and involves no unusual technique. 5. The results are in good agreement with both the theoretical and those obtained by other methods. REFERENCES 1. Street, The Analyst, 61, 687 (1936). 2. Schaal, Seifensieder Ztg.. 63 (1936). 3. Randa, Oil and Soap, 14, 7 (1937). 4. Silman, Soap 12, No. 3, 63 (1936). 5. Smith, American Perfumer, J u l y 70(1937).