FOR THE MICRO-CHEMIST ACCUSTOMED TO THE FINEST!
25
DKOS
BUNGE
TWO-PAN RIDERLESS MICRO BALANCE
Faster and more efficient. The conventional rider is replaced by automatic fractional weight loader (1 mg-10 mg) operated by dial on front panel. Auto matic swing-out device lifts pan from resting position to outside weighing compartment for loading. Housing design affords rapid temperature equaliza tion and easy accessibility to pan for positioning absorption tubes. Together with air damping, these features make the 25 DKOS as rapid as single pan competitive models. Capacity: 30 g Micro Scale: 0 m g - 1 m g Sensitivity: 0.001 m g Est. to: ± 0.002 m g Mechanical Weight Selection: 1 m g - 9 9 0 m g Knife Edges a n d Planes: A g a t e The Ultimate in Weighing Precision 0.0000001g (0.1 jug) with the
BUNGE 25 UM ULTRA-MICRO BALANCE CAPACITY: SENSITIVITY: 2 mg optical scale 0.1 Ag 9 mg automatic weight loader Estimations to ± 0.01 ng 2.5 g built-in tare weights 2.511 g Total O U T S | D E LOADING: By automatic pan extraction through front panel
IKA UNIVERSAL AUTOMAT MICRO COMBUSTION APPARATUS permits faster and more accurate determinations of C, H, N , Of S and Halogens with controlled temperature to 1200° C. Both heaters are hinged for easier insertion and removal of combustion tube and to provide faster cooling. All controls are on the front panel with separate tempera ture indicators for long and short heaters. The heater ele ments are completely imbedded in ceramic to prevent break age and oxidation. The Universal Automat may be used for semi-micro deter minations by merely interchanging heaters.
SPECIFICATIONS Long heater provides temperatures up to 1200° C within 20 minutes. Cooling time from 1200° to 180° C in 10 minutes. Short heater travel time variable
Short heater provides tempera tures up to 1200° C within 8 minutes. Cooling time from 1200° to 50°C in 10 minutes. from 5 to 30 mm per minute.
Pfaltz & Bauer, Inc. EMPIRE STATE BUILDING. NEW YORK
CHickering 4-6485
SCIENTIFIC INSTRUMENTS • CHEMICALS • BIOLOGICAL STAINS • ESSENTIALS OILS SOCIALISTS IN BECKMAN INSTRUMENT SALES AND SERVICE • MICROSCOPES, BALANCES AND ALLIED EQUIPMENT Circle No. 119 on Readers' Service Card 66 A
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ANALYTICAL CHEMISTRY
NEW BOOKS The Interpretation of NMR Spectra. K. B. Wiberg and B. J. Nist. vii + 593 pages. W. A. Benjamin, Inc., 346-5 Broadway, New York 25, Ν. Υ. 1962. $25. This book presents theoretically cal culated N M R spectra in a format t h a t can be used for comparison with ob served spectra making it possible to estimate coupling constants and chem ical shifts. T h e spectra were calcu lated with t h e aid of the IBM-709 computer, the plots have been pre pared by the computer and printed out b y associated equipment. The chemical shift between A and Β has been maintained at 6 s e e r ' , correspond ing 0.1 p.p.m. at 60 mc. T h e plots were m a d e b y replacing t h e spectra lines with Gaussian curves having a width of 0.3 sec.- 1 at half height, fol lowed b y summing t h e curves where they overlap. T h e data supplied with the spectra a r e : the spin coupling constants; a sorted list of frequencies and intensi ties; and the intensity of t h e highest peak in the plot.
Ionization Constants of Acids a n d Bases. Adrien Albert, E. P. Ser jeant, xii -f- 179 pages. John Wiley Park Ave.. South. New York 16, Ν. Υ. 1962. $3.75. This practical m a n u a l is written for those who, without previous experi ence, wish to determine an ionization constant. In addition, more advanced instruction is provided for those who wish to extend their range of tech niques. T h e first examples require only a few, very simple calculations; more complicated calculations are in troduced as gradually as possible with full explanatory detail. Help in the interpretation of ioniza tion constants is given ; it is shown how they are related to solubility and how they are used for deciphering an unknown. T h e last chapter deals with the determination of the stability con stants of metal complexes.
Physics a n d C h e m i s t r y of Electronic Technology. H. L. Van Velzer. xii + 372 pages. McGraw-Hill Book Co.. Inc., 330 West J,2nd St., New York 36, N. Y. 1962. $10. This book was originally prepared as a text for laboratory technicians to increase their understanding of vac u u m - t u b e fabrication. I t is written for the nonspecialist whose formal technical education is limited or non existent. Among the specific subjects
