Heath pH/Electrometer with New Recorder Features!
New features have been added to the Heath/Malmstadt-Enke EU-301 pH/ Electrometer, increasing the efficiency and reliability of the recorder: • New circuit board construction • New 3-terminal floating ground input • New drive geometry assures uniform pen response with low friction • New, more convenient operating controls plus . . . The EU-301 pH Recording electrometer can measure and record a span of 1 pH Unit on a full 10" scale. It performs also as an electrometer, accepting source impedance as high as 1000 Megohms. • Multi-pH ranges: full scale pH spans of 1, 2, 5, 10 and 14. Any 1 (or 2, 5 . . .) pH unit over entire region of interest can be switched for full scale on 10" scale or recorder chart • Multi-mV ranges: full scale mV spans of 50, 100, 200, 500, 1000 and 1400. 14 calibrated 50 mV increments of zero suppression can be switched in on all mV spans
Far more information on Heath pH/Electrometers and other teet instrumenta send for the Heath Scientific Instrumentation Catalog.
$315* $399*
HEATH COMPANY, Dept. 520-01 Benton Harbor, Michigan 49022 •
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Circle No. 122 on Readers' Service Card
114 A .
onally across from the conductance, t h e value of which a t balance gives t h e conductance directly. Of course, t h e scale is n o t linear, b u t t h a t is t h e n a t u r e of t h e beast. Under a p p r o p r i a t e conditions of measurement, t h e use of d.c. can furnish conductance measurements in no wise inferior to a.c. measurements. I t would be profitable to study brief pulses of d . c , possibly with periodic reversal of polarity, to minimize small polarization effects.
• Direct reading: pH is read directly from the 10" scale; expanded ranges are made direct reading by interchangeable scales (e.g. 6.000-8.000 pH) • Scale readability: 0.1% of full scale span, up to 0.001 pH and 50 uV on lowest spans • High Accuracy: better than 0.5% of any full 0.005 pH on span of 1 • Accepts glass and calomel electrodes: Beckman, Corning, Leeds and Northrup, Thomas . . . without adapters and accomodates electrodes of different diameters • Temperature compensated: manual adjust from 0 to 100° C or automatic control by accessory probe • Versatile Recording Speeds: Standard chart speed is 2"/min., other interchangeable chart drives ranging from l/2"/hr. to 12"/min. are available • Modular design: adapts to plug-ins or modules. Recorder may be separated for other applications. • Fully factory assembled, adjusted and calibrated. A unique design with unequalled versatility and excellent performance make this unit a highly valuable instrument in any laboratory.
EU-301A, w i t h Single-Speed Interchangeable Chart Drive Motor EU-301N, w i t h 21-Speed Chart Drive
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INSTRUMENTATION
ANALYTICAL CHEMISTRY
EK-272
See ACS Laboratory Guide for All Products/Sales Office
I t is conceivable t h a t direct automatic weighing of effluent droplets could be worked out. T h e y would certainly be of general applicability. T h e Calm Electrobalance could be used or a light cantilever beam with strain gauge or photoelectric readout. A t least we are aware of t h e pitfalls t o be encountered. F o r freely falling drops, t h e density as well as surface tension effects have to be considered. T h e latter are small for solutions of electrolytes b u t can b e high for m a n y organic systems. Most likely, it would be desirable to eject small, precisely defined volumes of effluent into a tiny, nonwettable weighing p a n . After a second or two for recording t h e weight, t h e contents of t h e p a n would be d u m p e d into a r e ceiver and become ready for t h e next sample. There is also t h e question of whether it would be practical to receive effluent droplets in a light liquid immiscible with t h e sample droplet a n d measure its rate of fall through the liquid photoelectrically. I n some systems, t h e sample could be recoverable, b u t there are obvious cases in which it would not. One m a y also ask if the famous Kelvin Electric Pail effect holds a n y promise. As he showed, droplets emerging from an orifice are electrostatically charged and by collecting them in a F a r a d a y cup relatively enormous potentials can be built u p . Presumably, such drops could be electrostatically deflected and preferentially so. M r . Conlon has done our readers a great service in outlining t h e reasons for renewed interest in liquid chrom a t o g r a p h y and in discussing t h e m a n y possible means, m a n y of t h e m already commercially available, for detecting t h e various fractions. O u r few observations a n d hunches m a y contribute little t o t h e main problem b u t we think it m u s t be realized t h a t in a sense we have run out of phenomena awaiting automation. W i t h present d a y instrumental techniques, some unusual and obscure effects m a y be worthy of study.
