This spark tells the strontium story

Yale University uses emission spectroscopy to study the geochemistry

of ancient and modern environments

The abundance of strontium in sediments and fossils helps today's geochemists paint a picture of ancient marine life. And strontium in contemporary materials such as human bones aids in evaluating the effects of radioactive fallout.

Emission spectroscopy is proving invaluable as a means of measuring the strontium concentrations in a variety of natural materials. Spectral values of sub­stances under test are compared with standards whose values have been obtained by stable isotope dilution analyses. The result: research findings with a high degree of accuracy, precision and sensitivity.

How NATIONAL Graphite helps measure strontium deposits

The substance of unknown strontium content is arced to completion at 16.5 amps in necked, deep cratered 3 /16" "Nat ional" electrodes. The resulting spectrum, recorded on film, tells the strontium story.

Be sure to specify "National" for your spectro­scopic work. This brand of graphite in electrode or powder form, is accompanied by a "statement of pur i ty" describing the trace-elements present. You are thus forewarned against errors arising from unex­pected spectral lines.

Ν Α Τ Ι Ο Ν A L TRADE-MARK

G R A P H I T E E L E C T R O D E S

U N I O N C A R B I D E

The terms "National" and "Union Carbide" are registered trade-marks of Union Carbide Corporation NATIONAL CARBON COMPANY · Division of Union Carbide Corporation · 30 East 42nd Street, New York 17, N.Y.

Sales Offices: Atlanta, Chicago, Dallas, Kansas City, Los Angeles, New York, Pittsburgh, San Francisco. In Canada: Union Carbide Canada Limited, Toronto. Fer further Information, circle number 54 A on Readers' Service Card, page 83 A

5 4 A · ANALYTICAL CHEMISTRY