JOURNAL OF RESEARCH of the National Bureau of Standards-A. Physics and Chemistry Vol. 64A, No. 1, January-February 1960 r >' Note on the Preparation of Sodium Amalgam in the Form of Pellets H. S. Isbell, H. L. Frush, and N. B. Holt (Augu t 26, 1959) ;:;I ~\. procedure is described for the preparation of sodium amalgam in the form of pellets. In connection with the development of m ethods in a hydrocarbon solvent, such as heptane or Loluene, for the synthesis of radioactive carbohydrates/ a quickly blotted dry, and dropped through the neck procedure and apparatus were previously described of the Hask into the mercUl'Y; the stopper is immedi­ ~ [1,2,3]2 for the I'cducLion of sClll.imicro qUUlltitics of ately replaced. The sodium reacts quicldy with the aldonic lactones to sugars. The method employs mercury and may be added fairly rapidly because of sodium amalgam together with a sligh tly soluble, the atomosphere of nitrogen. After the addition of acid salt (sodium binoxalate) as bufIer.3 The the sodium is completed , the Hask is heated with a ! amalgam is used in the form of pellets made by dropping the molten amalgam into a "sho t tower" of oil. Because other 'workers have had difficulty in ..l, making these pellets, the procedurc is now givcn in detail . The amalgam is preparrd in a 500-ml, rou nd­ bottomed, stainless-steel flask having a single neck, with a 24 /40 standard-taper joinL (o uLer),4 and a thermometer inlet. The joint is fiLted with a sLain­ - less-steel stopper , which has an inlet tube bent at .~ . right angles to the stopper and covered with asbestos for convenience in handling. The fl ask is held in a :;l sturdy, asbestos-covered clamp, which serves as a handle for th e vessel during th e heating step. An alundum (Soxhlet extraction) thimble 45 mm in diam, in the bottom of which six 1. 5-mm holes have ) been drilled, is held in a second asbestos-covered clamp. The oil bath is a thick-walled heat-resistant glass jar, 6 in. in cliam and 18 in. high, containing "' paraffin oil to within 3 in . of the top (see fig. 1). To prepare the amalgam, a weighed amount of mercury is placed in th e flask, into which a continu­ ous stream of dry nitrogen is passed by means of the inlet tube of the stapper. The required amount of sodium 5 is weighed under paraffin oil , and then cut into pieces just small enough to be readily slipped ~ through the neck of the flask . E ach piece is rinsed I A project sponsored by the Division of Research of the Atomic Energy Com· mission. 2 Figures in brackets indicate the litcrature references at the end of this paper. 3 The reduction procedure has also been modified for use with macro quantities of lactones [41. • Scientific Glass Company, Bloomfield, )1.J. • For the reduction of aldonic lactones under tbe conditions employed in this F LaURE 1. Apparatus used in the prepm'ation of sodium laboratory a 5-percent amalgam bas been found to be satisfactory. amalgam pellets. 135 Meeker burner until the amalgam is entirely molten. (The presence of remaining solid particles in the amalgam may b e detected by the sound of their impact on the walls of the flask when it is given a gentle, swirling motion.) While the amalgam is being pre­ pared, the alundum thimble is heated over another Meeker burner by a second operator. The hot thimble is then so clamped that its bottom is 1 to 2 in. above the surface of the oil, and the molten amalgam is poured into the thimble from the ther­ mometer inlet of the flask. The amalgam flows through the holes in the bottom of the thimble, drops through the oil, and collects at the bottom of the oil bath as small, rather flat pellets. Optimal conditions for the production of smooth pellets must be determined by trial. If the flask and thimble have not been sufficiently heated, the amalgam may solidify in the thimble. If the holes .A in the thimble are too large, the product may be , I somewhat " thready." However , once the optimal conditions have been established, the procedure may be repeated without difficulty. The entire operation must be performed in an efficient hood. The amalgam is stored under paraffin oil in a wide-mouthed, screw-capped bottle (see fig. 2) . Pellets are removed as needed, weighed under oil, and rinsed with an inert, volatile solvent im­ ;'--, m ediately before use. References FIGURE 2. Sodium amalgam pellets. [1] H . S. Isbell, J . V. Karabinos, H. L. Frush, N. B. Holt, A. Schwebel, a nd T . T . Galkowski, J . Research NBS 48, 163 (1952) RP2301. [2] H . S. Isbell, U .S. Patent No. 2,632,005, Mar. 17, 1953. [3] H . L. Frush a nd H . S. Isbell, J . Research N BS 50, 133 (1953) RP2400. [4] H . L. Frush and H . S. Isbell, J . Research NBS 54, 267 (1955) RP2588. W ASHING'rON, D.C. (Paper 64Al-35) 136 , L Publications of the National Bureau of Standards* Selected Abstracts components of the recording system-the reservoir of material or energy, the marking point or matrix positioned by the measuring element, and the chart surface which preserves Surface-wave resonance effect in a reactive t he record. cylindrical stI'ucture excited by an azial line source, A. L . Cullen, J. Research NBS 64D, No . 1, Energy dissipation by fast electl'ons, L. V. 13 (1960 ). pencer, NBS Monograph 1, 70 (1959) 45 cents. It is shown that a pLll'ely reactive cylinder excited by a Tabulations are given of the energy dissipated by fast elec­ neighboring line source can, under suitable conditions, give trons at different distances from nomoenergetic electron rise to a radiation pattern closely approximating the function sources, for plane perpendicular and point isotropic sources. cos nO. A summary of the theoretical methods and data utilized, and In a numerical example, a cylinder of three T.E.M. wave­ a table of spatial moments are also included. ') lengths circumference has a sLll'face reactance chosen to f emphasize the term cos 60 in the Fourier series of the result­ Calculated behavior of a fast neutron spec­ ant radiation pattern. It is shown that only 1.1 percent of the total power delivered to the line SOLll'ce is radiated in trometer based on the total absorption prin­ unwanted modes. ciple, J. E. Leiss, Tech. Note 10 (PB151369) $1.00. I t is also shown that the position of the line source does not Performance calculations for a total absorption fast neutron affect this result to first order provided that k(b-a)« l , spectrometer are presented. The spectrometer detecting where b-a is the distance of the line so urce from the cylin­ element is a boron-10-load ed liquid scintillator. By making drical surface. t he scintillator a thin disk, only those neutrons whose first collision is a large-energy-loss hydrogen collision have appre­ Basic experimental studies of the magnetic field ciable chance of remaining in the spectrometer long enough from electromagnetic sources immersed in a to be captured. The expected energy resolution and efficiency of this type of spectrometer are determined , and are com­ semi-infinite conducting medium, M. B. parable to other types of fast neutron spectrometers. Kraichman, J. Research NBS 64D, No.1 , 21 (1960 ). Using electromagnetic sources, consisting of various dipole, Penetration of gamma I'ays from isotropic and loops immersed ina concentrated sodium chloride solution, sources through aluminum and concrete, M . J. measurements were made verifying the magnetic fi eld propa­ Berger and L. V. Spencer, Tech. Note 11 (PBI51370) gation equations in air, derived previously by several authors. The receiver was farther away from the SOLll'ce than a wave­ 50 cents. length in the conducting medium, but much closer than a Semianalytical expressions, with numerically specified param­ wavelength in air. eters, are given which represent the gamma ray dose distribu­ An expression is derived giving the value of t he magnetic tion in infinite aluminum or concrete media for sources that fi eld in air due to a rectangulnr loop with a horizontal axis by are monoenergetic (with energies betwee n 10,22 Mev and assuming the loop to consist of two electric dipoles correspond­ 0.0341 Mev), iso tropic, and have the form of an infinite plane, ing to the horizontal members. Experimental data verifying point, disk, or spherical surface. this expression are presented. Also, using submerged electric dipoles, measurements were Precise time synchronization of widely sepa­ made of the magnetic fi eld in air which show that the fi eld is determined solely by the cLll'rent in the horizontal radiating I'ated clocks, A. H . Morgan, Tech. Note 22 wires of the dipoles. (PB151381) $1.50. This paper describes known prescise m ethods of setting a Determination of the amplitude-probability group of widely separated clocks to precisely the same time distribution of atmosphel'ic radio noise from and keeping them in close agreement indefinitely; most of the proposed methods are now available. An estimate of statistical moments, W. G. Crichlow, C. J . the accuracies of each m ethod are given, Some discussion Rouhique, A. D. Spaulding, and W . M . Beery, of high frequency radio propagation theory pertinent to two J . Research NBS 64:D, No.1, 49 (1960 ). of the methods and a few sets of measurements of the propaga­ tion delay time of high frequency signals from WWV to During the International Geophysical Year, the National WWVH are given, Several graphs and tables are included Bureau of Standards established a network of atmospheric to simplify some of the calculations.