ANALYTICAL CHEMISTRY
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information for those interested in studies of trace elements in the fields of medicine, toxicology, industrial hygiene, and, except for the flame methods, in studies of plant and soil problems. Although some very important studies on lead, antimony, and beryllium among others have been successfully carried out in the above fields by the use of emission spectrography, no mention is made of this work. Another oversight is the failure to refer to Feldman’s porous cup method of excitation. This significant American contribution to excitation sources should not have been omitted in any book supposedly nritten to record the more recent advances in emission spectrochemical analysis. JACOBCHOLAK
A.S.T.M. Standards 1949. Six Volumes. 1400, 1170, 1370, 1320, 1730, and 1410 pages. American Society for Testing Materials, 1916 Race St., Philadelphia 3, Pa., 1950. Volumes 1, 5, and 6, $10 each; 2, 3, and 4, $8 each; complete set $54. The 1949 revision of A.S.T.M. Standards has been issued in six parts and in its expansion from the previous five volumes of 1946, it reflects the increasing demand by industry for the society to investigate materials and establish specifications for them of properties, methods of sampling and test, which may be used as criteria for their manufacture and use. In the more than 8200 pages there are 1586 standard and tentative specifications. The standard specifications have the approval of the society as representing the conclusions of the membership. The tenta-
tive specifications have been accepted by the society for use and trial before adoption as standards and express the best current practices as submitted by experts in each field. One change, which seems commendable, is the grouping of the standards and tentatives together for each section rather than presenting the standards first and then the tentatives. Part 1, Ferrous Metals, covers mostly A, three B, and a feu E serial designations. The E serial designations in this part are general methods of test or recommended practices as the chemical methods for metals, for both Part 1 and Part 2, are published separately. Part 2, Non-Ferrous Metals, includes some A, but mostly B, and a few E serial designations (general methods), Part 3, Cement, Concrete, Ceramics, Thermal Insulation, Road Materials, Waterproofing, and Soils, is made up for the most part of C and D serial designations with a few E. Chemical methods of test are given in this part as well as the other physical and general methods of test. Specifications for thermometers are found under the E serial designations of this part. Part 4, Paint, Naval Storee, Adhesives, Paper, and Shipping Containers, deals with D for the most part and some E serial de sign a tio n s . Part 5, Electrical Insulating Materials, Plastics, Rubber, is mostly D with a few E serial designations. Part 6, Textile Materials, Soap, Fuel, Petroleum, Aromatic Hydrocarbons, and Water, is made up mostly of D with a few E serial designations. JANE HASTITG~
Optical Society of America The following abstracts of interest to analysts are taken from papers presented a t the annual meeting of the Optical Society of America held in Cleveland, Ohio, October 26 to 28, 1950. Infrared Absorption Spectra of Twelve Chlorinated Benzenes. EARLE K. PLYLER, rational Bureau of Standards. The infrared absorption spectra of chlorobenzene, three dichlorobenzenes, three trichlorobenzenes, three tetrachlorobenzenes, and penta- and hexachlorobenzenes have been measured from 2 to 38p. Many bands have been found in the spectra of these compounds. More bands are present in the spectra of the unsymmetrical substituted benzenes than in the symmetrical compounds. The spectrum of hexachlorobenxene is almost free of bands from 2 to 7p. The bending and stretching vibrations’of C-Cl have been assigned to certain frequencies of the different molecules. A study of the spectra has revealed some regularities among the absorption bands of the different molecules. The spectral regions m-here these regularities are most prominent are located a t 5 to 6p, 12 to 15p, and 18 to 25p; and an empirical identification of these compounds is possible by an examination of these three regions. I t is also possible to formulate empirical rules for the identification of the different isomeric chlorinated benzenes. New Recording Comparison Microphotometer. HUMEZ, Jarrell-Ash Co.
DAVIDE.
The microphotometer, a modification of the Jarrell-Ash Co. comparison microphotometer, achieves high sensitivity by the use of a 931 A. photomultiplier tube. Clear plate area of 5000 square microns produces full-scale deflection. Stability with respect to line-volta e changes is achieved by means of a power supply (selfcontained? which varies the sensitivity of the phototube inversely as the intensity of the light source. An unusual feature of the instrument is the plate-drive speed selector. Twelve plate-drive speeds, ranging from 0.05 to 25 mm. per minute, are selected by a single 12-position switch. Another switch is provided for forward, off, and reverse. A large panel-type galvanometer is mounted directly behind the viewing screen, making it possible to monitor the recording process while viewing the spectrum. The recorder, a modified Brown self-balancing recording potentiometer, is cable-connected to the microphotometer and may be
placed a t any distance from it. Measurements of which a record is not desired may be obtained by means of the monitoring meter. During these measurements a toggle switch is thrown which disconnects the chart-drive motor and the input signal but leaves the recorder amplifier connected, ready for instant use. The unit is compact, capable of high resolution, and relatively insensitive to vibration. Design of a Multiple Reflection Raman Tube. JOHSU. WHITE, White Development Corp., Stamford, Conn. A new Raman tube has been designed to increase the intensity
of light obtainable from small samples. With it a series of virtual images of the illuminated sample is projected into a line behind it, so that light from each image i.; seen through the preceding images, the light from the last image actually passing back and forth through the cell many times before emerging. Except for transmission losses, a proportionate increase in the illuminated length of sample is realized without loss of angular aperture. For a 5-cc. sample the calculated intensity is five times that obtainable in a single traversal. -4new lens whose last surface has its center of curvature in the focal plane is used to make the cell’s performance independent of the refractive index of the sample. The Influence of Noble Gases on Emission Spectra in the Direct Current k c . BERTL. VALLEE, CHARLES B. REIMER, AND Massachusetts Institute of Technology. JOHN R. LOOFBOUROW. The use of argon and helium as an environment for the direct current arc brings about changes in the signal, noise and signal to noise characteristics of spectra produced in the direct current arc An airtight arc stand w~tsused into which these two gases and their mixtures with carbon dioxide and oxygen were introduced. For many elements the replacement of air by these gases increases the signal to noise ratio of the lines. Helium and argon differ in their effects. Generally the addition of 2 or 3y0 of oxygen or carbon dioxide to argon or helium would not alter the signal to noise ratio from that obtained in pure argon and helium. Preliminary experiments with argon and helium show that markedly increased sensitivities due to line enhancement may be obt nined a t either high or low amperage when the concentration of elements in the matrix is greatly decreased. This method seems to
