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tensity and steadiness of the signals in flame photometry and atomic absorption spectroscopy. In both techniques, air-fuel ratio, flame position, and sample feed rate have important effects. Generally, said Robinson, flame photometry is most useful for determining group 1 and 2 elements and many transition elements. It is of little use for noble metals, the zinc sub-group, and non-metals. Atomic absorption spectroscopy works well for noble metals, the zinc sub-group, and transition elements, but not for the analysis of non-metals and metals such as aluminum and vanadium that form refractive oxides. Best operating conditions for the two methods vary widely. A low feed rate (0.06 ml. per min.) and use of the spectrum from the tip of the inner cone is best for flame photometry. On the other hand, atomic absorption spectroscopy works best with a feed rate limited to the rate of combustion of the solvent in the flame and with a signal from the flame's outer cone. Ion Exchange Separations. Several variations of ion exchange technique were described by Dr. James S. Fritz of Iowa State University. Complexing with EDTA (ethylenediamine tetraacetic acid) and close control of pH gives excellent quantitative separation of metal ions with short—five cm. —columns. On the basis of studies of individual ions, Dr. Fritz said that separation of mixtures may be predicted. Another use of ion exchange columns is separation of metal groups by
"Guessing games" are out-of-place in today's busy laboratories. So it's wise to bear these important facts in mind when you consider laboratory sinks: There is no question of which sink takes which corrosive (weak, mixed or concentrated) when you install "U. S." Chemical Porcelain Laboratory Sinks. One "U. S." sink handles 'em all, hot or cold ! Even hydrofluoric acid and hot caustics can be safely handled with normal routine rinsing. No "chemical resistance" tables required. No chance for error and costly damage. Sinks made of solid, non-porous chemical porcelain also have the other features you want. Attractive appearance. Time-tested durability. Superb heat-shock resistance. Smooth glazed surfaces, rounded corners for easy cleaning. Non-staining, non-absorbent, no maintenance problems. See the wide range of standard types and sizes at your Laboratory Furniture Dealer. Or write direct for new Bulletin L-8R.
CHEMICAL CERAMICS
DIVISION
U. S. STONEWARE AKRON 9. OHIO Circle No. 14G on Readers' Service Card 48 A
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ANALYTICAL CHEMISTRY
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U. S. and foreign speakers were on the LSU program. One of the foreign visitors. Dr. Robert Mitchell, Macaulay Institute for Soil Research, Aberdeen, Scotland (left) is shown with Dr. James W . Robinson, Esso Laboratories, Baton Rouge, La.
