impurities never exceed 6 ppm in ^ I J A T I O N A L spectroscopic products! Our testing standards are the highest avail­able anywhere today!

This is proved daily with the Densitom­eter, Spectrograph and other modern test­ing equipment.

So exacting are National Carbon's test­ing procedures that small special preform orders often require double the pieces or­dered to ensure a statistically significant sample.

With the Densitometer the line density of each element is accurately measured. From these measurements we can calculate

the extent of any trace element in parts per million. For example, the amount of silicon present is calculated from the density of the silicon line-2881.578A.

This and other precise, dependable tests enable National Carbon to include with each order a "Statement of Purity"— guar­anteeing total impurities not to exceed 6 ppm in NATIONAL spectroscopic products.

Such consistently high purity levels as­sure the spectroscopist that his results will not be affected by elements present in un­known concentrations.

"National" and "Union Carbide" are registered trade-marks for products of

NATIONAL CARBON COMPANY Division of Union Carbide Corporation-270 Park Avenue, New York 17

In Canada: Union Carbide Canada Limited, Toronto Circle No. 90 on Readers' Service Card

UNION CARBIDE

1 0 6 A · ANALYTICAL CHEMISTRY Circie No. 113 on Readers' Service Card-

The DENSITOMETER

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