U. S. DEPARTMENT OF COMMERCE JESSE H. JONES, Secretary NATIONAL BUREAU OF STANDARDS CIRCULAR OF THE NATIONAL BUREAU OF STANDARDS C440 For sale by the Superintendent of Documents, Washington, D. C. Price $2.75 REPLACING M168801 TI 435 PREFACE This Circular supersedes National Bureau of Standards Circular No. 12, issued July 6, 1906, and Circular No. 44, issued January 15, 1914, and revised November 1, 1917. The main object of this treatise is to explain the application and manipulation of polarized light for industrial, analytical, and theoretical purposes. The principal application of polarized light is embodied in the many modifications of the polariscope. The increasing applications of polarized light to the arts and sciences has led to a proportionate increase in the requests made to the Bureau for information. In this Circular an attempt is made to answer as far as possible such inquiries as well as furnish information of a broader character and in greater detail than could be given by letter. In order to present the necessary explanations, simple physical conceptions and deductions have been used. Such explanations, however, are not to be construed or interpreted as an explanation of the physical theory of optical activity. In spite of the numerous mathematical treatments of this subject in recent years, and in spite of the important contributions to the subject of the structure of naturally optically active compounds from the chemical viewpoint, a satisfactory explanation of the phenomenon which comprehends existing experimental facts is still lacking. The general subjects of magneto and electro optics in relation to polarized light are not discussed, as they do not come within the province of this treatise. Van't Hoff and Le Bel discovered how to select from substances of known chemical structure those substances which produce an angular rotation of the plane of polarized light. There followed a widespread utilization of the polariscope in the chemical industries and in chemical research. However, despite the voluminous researches which resulted and the fact that physicists have probed deeply into the nature of light in general and polarized light in particular, as well as the nature of the ultimate particles of which all substances are built up, the mechanism of the interaction between polarized light and the structure of optically active substances is still in a state of controversy, as illustrated by the theories of Born, Kuhn, Boys, and others. No attempt therefore has been made to present a picture of the present controversial state of the physical theory of the nature of optical activity. As a justification for the special applications of the polariscope given in this Circular, it may be stated that carbohydrate chemistry, and carbohydrate industry dependent upon carbohydrate chemistry, could hardly have developed to the magnitude it has attained in recent years without the aid and guidance of the polariscope. Conversely, no better insight into the various applications of quantitative measurements with the polariscope can be given than the study of the specific investigations of carbohydrate chemistry. The application of the polariscope in other fields of chemistry, such as essential oils, hydrocarbons, alkaloids, and other optically active substances, will present no difficulties to the chemist familiar with its application in carbohydrate chemistry. Because of this fact, carbohydrate investigations have been given a prominent place in this Circular. The following members of the staff have collaborated in preparing the material for this publication: Frederick Bates, N. L. Bowman, D. H. Brauns, J. F. Brewster, C. S. Cragoe, Harriet L. Frush, P. E. Golden, L. D. Hammond, Mary L. Hubbell, H. S. Isbell, R. F. Jackson, Emma J. McDonald, F. P. Phelps, W. W. Pigman, M. J. Proffitt, J. B. Saunders, C. F. Snyder, and A. Q. Tool. LYMAN J. BRIGGS, Director. UNITED STATES DEPARTMENT OF COMMERCE. Sinclair Weeks, Secretary NATIONAL BUREAU OF STANDARDS. A. V. Astin, Director U.S.S.D. For sale by the Superintendent of Documents, U. S. Government Printing Office Temperatures: Tables of Recalculated Values J. F. Swindells, C. F. Snyder, R. C. Hardy, and P. E. Golden The tables of viscosities of sucrose solutions appearing in NBS Circular 440 were calculated, assuming the value of the viscosity of water at 20° C to be 1.0050 centipoises. Subsequently, a redetermination of the absolute viscosity of water at 20° C established the value 1.0020 centipoises. In addition, more precise values have been obtained for the calibration constants of the viscometers used in the original measurements of sucrose solutions upon which the tables were largely based. Incorporating these more precise values, the above tables have been recalculated. At the Eleventh Session of the International Commission for Uniform Methods of Sugar Analysis at Paris, 1954, the report on Subject 19 presented by the Referee, A. Van Hook [1],2 called attention to the determination of the viscosity of water at 20° C at the National Bureau of Standards [2]. This value 0.01002 poise has been adopted by the National Bureau of Standards, the American Society for Testing Materials, the National Physical Laboratory in England, and the Physikalische-Technische Bundesanstalt in Germany. The Referee's report also pointed out the desirability of a standard set of viscosity values of sucrose solutions. A discussion of the subject of viscosity of sucrose solutions is given in chapter XXI of reference [3]. In the chapter, reference is made to the work of Bingham and Jackson [4] and to Landt's comprehensive review [5] of all data published up to 1936 and his comparison of this with the experimental values on solutions containing 60 to 84 percent of sucrose. The lack of agreement disclosed by this review [5], together with indirect evidence that some of the interpolated values given by Bingham and Jackson [4] were in error by several percent, led to a further investigation at NBS by J. F. Swindells, R. F. Jackson, and C. S. Cragoe [3, p. 357]. The values obtained in this study were used as the major basis for the calculation of tables 130, 131, and 132, pages 671 to 673 in Circular 440 [3]. Viscosity measurements were made over the range 0° to 35° C on solutions containing 30, 40, 50, 60, 65, 70, and 75 percent of sucrose by weight in vacuum. These solutions were initially prepared with a precision of better than 0.001 percent in the concentration, using sucrose of the highest purity. Changes in the initial concentration during the filling of the viscometers were minimized by special precautions described in chapter XXI [3]. Three instruments similar to the one described by Bingham and Jackson [4] were employed with capillaries of different diameters. The instrument with the smallest capillary was calibrated with water at 20° C, assuming the value 1.0050 centipoises. The calibrations of the other instruments were carried out with several liquids of higher viscosity in a step-by-step process. Drainage errors were eliminated by always flowing the liquids into a dry bulb. A separate sample was used for each viscosity determination. At least two measurements, usually agreeing to 0.1 percent or better, were made at each 1 Supersedes tables 130, 131, 132, and 133 of National Bureau of Standards Circular 440, Polarimetry, saccharimetry, and the sugars (1942). 2 Figures in brackets indicate the literature references on page 3. temperature, which was adjusted to the desired integral temperature (indicated by a platinum resistance thermometer) and usually maintained constant to less than 0.01° C. The very precise measurements by Jones and Stauffer [9] of the viscosity of 20-percent-sucrose solutions at 25° C were used as the primary basis for the fixation of the viscosity values for 20-percent solutions. The values above 35° C were based largely on the results of Bingham and Jackson [4], Landt [5], and Bennett and Nees [6]. In all of the above data, the value of the viscosity of water at 20° C (0.01005 poise) accepted at that time (1942) was used. The acceptance of this value was deemed feasible because at that time the value 0.01005 was generally employed. However, during the period 1938 to 1941, an investigation of the viscosity of water at 20° C and other temperatures was in progress at NBS by Coe and Godfrey, who reported the tentative value 0.010020 poise at 20° C in a letter to the editor of the Journal of Applied Physics [7]. It was recognized, however, that with the completion of so small a part of the contemplated series of measurements of water, the statement of this tentative value at that time was justified only by the necessity of indefinitely suspending the work. The work was resumed in 1947 by J. F. Swindells, who completed the experimental program and reduced all the data. The final result of the completed determination was found to be 0.010019 0.000003 poise. The magnitude of the uncertainty in this value is such that the simpler value of 0.010020 poise at 20° C has been adopted. During this latter period, 1947 to 1952, a critical study was in progress, which was related to the precise measurement of viscosity and included a detailed investigation of the constants of the identical viscometers used in the work of Swindells, Jackson, and Cragoe, which was the major basis for tables 130, 131, 132 of NBS Circ. 440 [8]. The recalculation of tables 130, 131, and 132 has been made by using the more precise values for viscometer constants and the new value for the viscosity of water at 20° C (i. e., 0.010020 poise). Data of other investigators, which were considered in arriving at the tabulated values in table 133, were adjusted to the new basis by application of the factor, 0.997015, which represents the ratio of the new to the old value for the viscosity of water at 20° C. It is recommended that the revised tables for the viscosities of sucrose solutions at various temperatures, presented in this Supplement, be substituted for the original tables in Circular 440. [1] A. Van Hook, Proc. International Commission for Uniform Methods of Sugar Analysis 11th Session, p. 88 (1954). [2] J. F. Swindells, J. R. Coe, Jr., and T. B. Godfrey, J. Research NBS 48, 1 (1952) RP2279. [3] Polarimetry, saccharimetry, and the sugars, NBS Circ. 440, p. 350 (1942). (Superintendent of Documents, U. S. Government Printing Office, Washington 25, D. C., price $4.25). [4] E. C. Bingham and R. F. Jackson, Bul. BS 14, 59 (1917) S298. [5] E. Landt, Z. Wirtscharftsgruppe Zuckerind. 85, 395 (1935); 86, 8 (1936); Zucker 6, 558 (1953); 7, 214 (1954). [6] A. N. Bennett and A. R. Ness, Ind. Eng. Chem. 22, 91 (1930). [7] J. R. Cce and T. B. Godfrey, J. Appl. Phys. 15, 625 (1944). [8] J. F. Swindells, R. C. Hardy, and R. L. Cottington, J. Research NBS 52, 105 (1954) RP2479 [9] G. Jones and R. E. Stauffer, J. Am. Chem. Soc. 59, 1630 (1937). ADDITIONAL REFERENCE H. Breitung, Z. Zuckerind., Berlin, 6, 185, 254 (1956). 463432-58 3 |