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O P T I C A L SERVICE For Laboratory Layouts & Production Interferometer Optics Michelson • T w y m a n • Mach-Zehnder • Fabry-Perot • Etalon Plates " M a t c h e d " 1/200 Wave up to 8" Dia. w i t h Spacers • Spherical Etalons Natural & Synthetic Crystals Fused Quartz • Single Crystal Quartz • IR Materials • Calcite Optics • Polarizers • Retardation Plates • Acoustical Rods • Flats • Mirrors • Prisms Laser Optics—(POLISHED for lasers) Brewster Windows · Sphericals • Polarizers • Mirrors • B e a m s p l i t t e r s • Prisms Lenses—Systems • UV & IR Sphericals • A c h r o m a t s • Parabolics • Off Axis • Cylindrical Coatings—Soft a n d Hard Multilayer Dielectric Reflective » Anti-reflective Filters Interference • Neutral Density • Color Glass Filters "Micro-Fused Quartz".* Substrates (as t h i n as .002") Surface Finish for T h i n Film Deposition a n d Biological Microscope Slides Registered trade mark WRITE OR CALL FOR CATALOG
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THE INSIDE STORY OF VRC"LP" VACUUM VALVES T h e new idea in v a c u u m gate valves . . . t w o - p i e c e c o n s t r u c t i o n assuring simplified in-line servicing . . . Available in sizes 2 " (37«"), 4 " (57«"), 6 " (7Ve") and 10" (117»") . . . Exclusive LARGE PORT design permits the valve to be e n l a r g e d for future piping requirements . . . test stand proven over 50,000 vacuum cycles, guarantees equivalent of 50 maintenance-free years in normal v a c u u m service. Write for complete engineering information V a c u u m R e s e a r c h M a n u f a c t u r i n g Co. A Division of Cenco Instruments C o r p o r a t i o n 3100 C r o w C a n y o n R o a d , San
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ANALYTICAL CHEMISTRY
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Radiochemical Method for Determination of Arsenic, Bromine, M e r c u r y , Antimony, and Selenium in Neutron-Irradiated Biological Material. Knur Samsahl
1480
Modification of the Fluoride Activity Electrode f o r Microchemical Analysis. R. A. Durst and J. K.Taylor
1483
Determination of Aliphatic a n d Aromatic Acids b y Pyrolysis o f Their T e t r a m e t h y l a m m o n i u m Salts. J.J. Bailey
1485
D e m o u n t a b l e H o t H o l l o w C a t h o d e L a m p as Ex c i t a t i o n Source in A t o m i c Fluorescence Flame Spectrometry. J. I. Dinnin and A. W. Hell
1489
A t o m i c Fluorescence Flame S p e c t r o m e t r i c D e t e c t i o n o f P a l l a d i u m , T i t a n i u m , Zirconium, C h r o mium, a n d Aluminum Using a H o t H o l l o w C a t h o d e L a m p . j . I. Dinnin
1491
Determination of Trace Quantities of 2,6-Di-ferfB u t y l - 4 - M e t h y l Phenol in P o l y e t h y l e n e Using Electron C a p t u r e G a s C h r o m a t o g r a p h y . R. E. Long and G.C. Guvernator III
1493
A Statistical M e t h o d f o r E v a l u a t i o n o f Detectable Sample Concentrations. John, W.J. McCarthy, and J. D.Winefordner
1495
Limiting P. A. Si.
Ion-Exchange Paper C h r o m a t o g r a p h y of Certain M e t a l Ions w i t h A q u e o u s - O r g a n i c W a s h Liquids. Joseph Sherma
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Correction. Estimation o f P r e e x p o n e n t i a l Factor f r o m Thermal Decomposition Curve of an Un weighted S a m p l e . R. N. Rogers and L. C. Smith . . .
1405
Correction. A Mechanistic I n v e s t i g a t i o n o f M o l y b d e n u m Blue M e t h o d f o r D e t e r m i n a t i o n o f Phos phate. S.R. Crouch and H.V.Malmstadt
1405
Correspondence O n D e r i v a t i o n a n d A p p l i c a t i o n o f the L i n e a r l i z e d Current-Potential Characteristic. D. M. Mohilner, Norman Hackerman, and A. J. Bard . . .
1499
S o m e A p p r o x i m a t i o n s f o r the Electrochemical Rate E q u a t i o n a n d Their A p p l i c a t i o n s . D. K. Roe and R. L. Birke
1501
A i d s for A n a l y t i c a l Chemists Rapid Determination of Paraffins. J. C. Suatoni
Trace
Aromatics
in 1505
R a t i o R e c o r d i n g o f M a s s S p e c t r a in C o m b i n e d G a s Chromatography-Mass Spectrometry. B. H . Kenneft
1506
A S i m p l e G e l a t i o n P r o c e d u r e f o r L i q u i d Scintilla tion Counting. J. N. Bollinger, W. A. Mallow, J. W. Register, Jr., and D. E. Johnson . . . .
1508
Programmed Temperature Gas Chromatography w i t h D u a l Electron C a p t u r e Detectors for Pesticide Residue A n a l y s i s . τ . J. Kneip, T. R. Beasley, P. King, and W. K. Dean
1510
