T H E JOURNAL OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
Oct., 1921
Bailey and Baldsiefen’s values for the per cent of linseed oil corresponding to a certain determined hexabromide number, when using oil mixtures containing oils having different analytical constants than those used by them in their investigation. The maximum deviations from their results will occur when the maximum or minimum values of the pure oil constants, as established, are used in the computations. I n the computations, the results of which are stated in Table 1, the determined iodine and hexabromide numbers recorded in Table I11 by Bailey and Baldsiefen were corrected to eliminate experimental errors by the method previously described, using the following constants for their oils: Linseed oil Soy-bean oil
Iodine Number Hexabromide Number 179.0 43.3 135.5 6.0
The per cent of linseed oil corresponding to the corrected iodine or hexabromide numbers was then computed for mixtures of the two oils having the widest range of analytical constants, and the difference between the true per cent corresponding to that iodine number or hexabromide number compared with the per cent stated by Bailey and Baldsiefen to correspond to the same iodine or hexabromide number.
SUMMARY 1-The modified hexabromide method gives results differing by 7 to -3 per cent from theactual amount of linseed oil in mixtures of linseed and soy-bean oils containing oils having the widest range of analytical constants, when Bailey and Baldsiefen’s results for mixtures of oils with average constants are used as a criterion for the determination of the per cent of linseed oil present in the mixture. 2-The experimental error of the modified hexabromide method may produce results differing by *6 per cent from the actual amount of linseed oil in the mixture. 3-In examining mixtures of linseed and soy-bean oil containing oils, the constants of which are unknown, results 13 to -9 per cent from the actual per cent of differing by linseed oil in the mixture are possible under these conditions. 4-The iodine number determination gives results differing by 16 to - 17 per cent from the actual amount of linseed oil in mixtures of linseed and soy-bean oils having the widest range of analytical constants, when Bailey and Baldsiefen’s results for oils with average constants are used as a criterion for the determination of the per cent of linseed oil in the mixture. 5-The experimental error of the iodine number determination may produce results differing by * 1 per cent from the actual per cent of linseed oil in the mixture. 6-The total error involved when the iodine number of mixtures of linseed and soy-bean oil, the constants of which are unknown, is used to ascertain the per cent of linseed oil in the mixture, may lead to results differing by +17 to -18 per cent from the actual per cent of linseed oil in the mixture. 7-In all cases, for mixtures of the oils, the modified hexabromide method gives more nearly accurate results than the iodine number determination. 8-The per cent of linseed oil in mixtures of the two oils can be ascertained within =t9 per cent, using Bailey and Baldsiefen’s results as a criterion, when mixtures of linseed oil with a maximum iodine number and soy-bean oil with a maximum or minimum iodine number are examined. &When mixtures of linseed oil and soy-bean oil with minimum constants are examined, the per cent of linseed oil as determined, using Bailey and Baldsiefen’s results as a criterion, may vary from the actual amount present by 0 to 12 per cent.
+
+
+
+
943
Preparation of Alcoholic Potassium Hydroxide Volumetric Solution’ By S. T. McCallum RESEARCH LABORATORIES, MCKESSON& ROBBINS,91 FULTONST.,N e w YORK,N. Y.
A perusal of the prominent authorities on the testing of oils and fats discloses the fact that only one general method is given for the preparation of 0.5 N alcoholic potassium hydroxide volumetric solution. This consists in dissolving the required amount of potassium hydroxide in a small amount of water and adding a sufficient quantity of ethyl alcohol which has been especially purified by some more or less tedious method. Even when great care is used in its preparation, the solution has a tendency to darken with age and exposure to light and also to lose in strength. For several years the author has used the following simple method for the preparation of this volumetric solution. The correct amount of potassium hydroxide (allowing for water and carbonate) is crushed quickly in a mortar and transferred to a volumetric flask. Sufficient Columbian methanol or purified wood alcohol is added to fill the flask to the mark. The flask is then shaken occasionally till the solution is complete. The carbonate which separates out should be filtered off through glass wool. The solution is now ready for standardization. No special purification of the Columbian methanol is required, the ordinary grade being satisfactory. A solution prepared as described above is not perceptibly darkened by exposure to light. The author has often made normal potassium hydroxide solution by this method which was practically colorless. If for any reason a water-white solution is required, all that is necessary is to distil the Columbian spirit in glass before making up the solution. Numerous comparisons of the solution with one made by the U. S. P. method showed no perceptible variation in saponification numbers obtained on the same oil. Association of Official Agricultural Chemists The thirty-eighth annual convention of the Association of Official Agricultural Chemists is to be held a t the Washington Hotel, Washington, D. C., October 24 to 26, 1921. The meetings will be held a t the hotel headquarters. The program includes reports of referees and special papers closely associated with the work of the Association. A special order for 11 o’clock on Tuesday, October 25, includes addresses by the president of the Association, Dr. W. F. Hand, the honorary president, Dr. Harvey W. Wiley. and by Senator E. F. Ladd. The Secretary of Agriculture will deliver an address at a special meeting in the afternoon of the same day.
Technical Association of the P u l p and P a p e r I n d u s t r y The Technical Association of the Pulp and Paper Industry and the American Pulp and Paper Mill Superintendents’ Association are to hold their joint meeting October 18 to 21, 1921. The meeting will open in Washington, D. C., with headquarters at the New Willard Hotel. After a day devoted to the reading and discussion of papers and visits of inspection to various government bureaus, the party will leave for a trip of mill and plant inspections. Wednesday, the 19th, will be spent a t York, York Haven, and Spring Grove, Pa. ; Thursday, a t Philadelphia, where the banquet will be held at the Bellevue-Stratford, and on Friday the members will visit plants a t Wilrnington, Del. 1
Received M a y 28, 1921.
