Contributed Articles
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COMPUTER COMPATIBLE MEASURING ENGINES
Separation of Isotopic Methanes by Gas Chromatog raphy. Fabrizio Bruner, G. P. Cartoni, and Massimiliano Possanzini
1122
Assay for Heroin in illicit Preparations Using Parti tion Chromatography. G. R. Nakamura and H. J. Meuron
1124
Determination of Hydrocarbon-Type Composition of Petroleum Distillates Boiling up to 185 ° C Using Type X Molecular Sieves. J. V. Brunnock and L. A. Luke
1126
Liquid-Liquid Membrane Electrodes Based on Ion Association Extraction Systems. C. J. Coetzee and Henry Freiser
1128
Polarographic Studies of Chloroacetones. and Ε. Μ. Harris
1130
M. E. Hall
Foam Separation of Lead(ll) with Sodium Lauryl Sul fate. Λ. J. Rubin and W. L. Lapp
1133
Study of Various Inorganic Phosphate Salts Impreg nated in Silicone Rubber as Potential Indicating Elec trodes for Phosphate Ion. G. G. Guilbault and P. J. Brignac,Jr.
1136
Determination of Selenium(IV) in Presence of Selenium(VI) Using Sulfur Dioxide. L. R, Williams and P. R. Haskett
1138
Spectrophotometry Determination of Hafnium as Reduced Molybdosulfatohafnic Acid. C. C. C/owers, Jr., and J. C. Guyon
1140
Correction: Reaction Rate Method for Ammonia Blood Urea Nitrogen Utilizing Pentacyanonitrosyloferrate Catalyzed Berthelot Reaction. T. E. Weichselb a u m , J. C. Hagerty, a n d H. B. Mark, Jr.
1015
HIGHEST ACCURACY Precision lead-screw driven Less than 1 m i c r o n backlash Better than 1 micron measuring accuracy X-Y indexing t o VA micron EIGHT AVAILABLE TWO-COORDINATE FORMATS: 50 mm X 250 mm 50 mm X 350 mm
50 mm X 450 mm 100 mm X 250 mm
100 100 130 250
mm mm mm mm
X X X X
350 mm 450 mm 250 mm 250 mm
X-Y indexing to V* micron is possible for manual or automatic positioning by high and low-speed s c a n ning motors.
Correspondence
VERSATILE This equipment can be made available with complete instrumentation for installations such as the f o l l o w i n g : Spectra-wavelength measuring comparators Star-plate measuring c o m p a r a t o r s Fast-scan densitometers High-resolution m i c r o p h o t o m e t e r s Film readers with position and density readout Continuously self-calibrating iris photometers
OxctUt/Hcope pattern permits Herniate line setthina with hi Send for brochures and formal Write or phone.
specifications.
GRANT INSTRUMENTS 1805 Eastshore Hwy., Berkeley, California 94710 (415) 548-0101 Circle No. 23 on Readers' Service Card
4 A
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ANALYTICAL CHEMISTRY
Note on Polarographic Theory for £ C £ Mechanism. Bertel Kastening
1142
Some Observations on Phenylfluorone Method for Determination of Tantalum. C. D. Bingham, M. S. Maseda, and B. G. Johnson
1144
Aids for Analytical Chemists Infrared Analysis of Heavy Water-Water Mixtures of Intermediate ( 3 - 9 7 % ) Concentration. R. D. Kimbrough, Jr., and R. W. Askins
1147
Some Simple Techniques to Prepare Powder Samples for Spark Source Mass Spectrometric Analysis. P.-K. Hon
1148
Simultaneous Spectrophotometric Determination of Nitrosyl Bromide and Bromine. Chiya Eden, Hans Feilchenfeld, and Shalom Manor
1150
Apparatus for Pumping Liquid Bromine and other Difficult Liquids in Continuous-Flow Systems. C. F. Ra/ey
1152
