4A
ANALYTICAL
CHEMISTRY
C O N T E N T S , continued Precision of Simple Flame Photometer J . U. W h i t e
394
Interlaboratory Study on Determination of Acetyl in Cellulose Acetate
' 40O
MICROCHEMISTRY
TO DETERMINE
MELTING POINTS
Determination of Microgram Quantities of Sulfide Sulfur B. L. Dunicz and Terkel Rosenqvist
404
Spectrographic Determination of Beryllium in Urine and A i r R. G . Smith, A . J . Boyle, W . G . Fredrick, and Bennie Zak
406
Photometric Determination of Microquantities of Arsenic C. E. Bricker and P. B. Sweetser
409
NOTES O N
ANALYTICAL
PROCEDURES
Determination of Free Carbon in Atmospheric Dust Robert McCarthy and C. E. M o o r e
411
Separation of 2,4-Dinitrophenylhydrazones of Some Substituted Benzaldehydes by Chromatographic Adsorption A . A . Rosen, K. V . Ύ. Sundstrom, and W . F. V o g e l
REICHEPT SINCE 1875
KOFLER HOT BENCH Developed primarily to determine quick ly the melting points and eutectic tem peratures of organic substances, the Kofler Hot Bench also provides a rapid method to observe the presence and be havior of water crystal, the process of decomposition and to judge volatility. The metal body is IV2" wide χ 14'/2" long and is electrically heated at one end to provide an almost linear temper ature d r o p . The temperature ranges from 50° to 2 6 0 ° C . The scale has temperature lines marked at every 2° and is read by a runner with pointer and tab. Test sub stances with known melting points are provided to gauge or set the instrument. To determine a melting point, the sub stance is laid directly on the chromeplated surface. With pure substances, there is a sharp dividing line between the solid and fluid stage. The runner is moved until the pointer rests on the d i viding line and the temperature is read from the scale. The margin of error is usually not more than ± 1 °C. Available
for prompt
delivery
FOR DETAILED I N F O R M A T I O N WRITE FOR CATALOG A B
National Representatives:
W M . J. HACKER & CO., Inc. 82 Beaver St., New York 5, Ν. Υ.
412
Mass Spectrometric Determination of Oxygen in Water Samples Israel Dostrovsky and F. S. Klein
414
Rapid Determination of Organic Acids in Cured Tobacco F. G . Houston and J . L. Hamilton
41 5
Technique for Noting Combustion in Oxygen Bombs C. H . Hale
416
Rapid Volume and Concentration Calculations in Industrial A i r Analysis P. W . M u l l e n
417
Ascorbic A c i d in Analytical Chemistry
418
Laszlo Erdey and Endre Bodor Chicago Chemical Conference
423
Symposium on Modern Methods of Analytical Chemistry Corrections
425 393, 426
CRYSTALLOGRAPHY Ethylenedinitramine W . C. M c C r o n e
DATA 421
SCIENTIFIC C O M M U N I C A T I O N
422
BOOK
422
REVIEW
THE A N A L Y S T ' S C A L E N D A R A I D S FOR T H E A N A L Y S T Wave Spreader for Precision Determination of Half-Wave Potential with Sargent M o d e l XII Polarograph D. N . Hume and T. W . Gilbert Thermostated Η-Cell for Polarography J. C. Komyathy, Francis M a l l o y , and P. J . Elving Adapters for Introducing H o t Coils into Distillation Flasks for Constancy of Ebullition Julian Feldman and Peter Pantages
427
431 431
432
THE A N A L Y S T ' S C O L U M N
15 A
INSTRUMENTATION
21 A
R. H . M i i l l e r N E W PRODUCTS MANUFACTURERS'
29 A LITERATURE
32 A
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