COLEMAN
GALV-O-METER makes easy work of precise measurement The Coleman Galv-O-Meter is a precision measuring instrument built around a taut-suspension galvanometer and a slide-wire potentiometer. Already of proven value in routine flame photometry and trace fluorimetry, it now is emerging as an important research tool. Its characteristics make critical analytical conditions
easy to establish and just as easy to duplicate. They are: GALVANOMETER SENSITIVITY — 1 micro-ampere full scale. POTENTIOMETER ACCURACY — better than 0.5%. The instrument's versatility is limited only by its user's ingenuity. Here are but a few of its major laboratory applications: • • • • • • •
indicating galvanometer precision potentiometer indicator in bridge circuits millivolt meter linear voltmeter microammeter photometer readout
Capitalize on this versatility to m a k e your own work easier. Write for Bulletin AB-261 COLEMAN I N S T R U M E N T S , INC. MAYWOOD, ILLINOIS Circle No. 73 on Readers' Service Card 102 A
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ANALYTICAL CHEMISTRY
INSTRUMENTATION ture differences of several degrees in two different adiabatie calorimeters with a linear temperature resolution of 105 to 1. The treatment is essentially one of combining the resistance temperature characteristic of the thermistor with those of the adiabatie calorimeter and its power input. By rearrangement of the respective equations, an equation in the form of a straight line is obtained, the least squares solution of which permits a precise evaluation of the constants. In a second calorimeter, heat input to the calorimeter was furnished by a standard half-gram radium source, rather than electrically. The high precision attained in these studies as compared with ordinary methods for thermistor calibration arises from the elegant and precise means for measuring the power input to the adiabatie calorimeter. Beryllium Analysis
A standard procedure in nuclear physics has been reversed, so to speak, to provide a selective and very sensitive means for the analysis of beryllium. For some years it has been possible to obtain low-level as well as high-level neutron sources from Oak Ridge. These sources consist of a cylinder of antimony inserted in a beryllium capsule and sealed in an aluminum jacket. The neutron emission is produced by the gamma-neutron reaction produced in beryllium by the hard yravs emitted during the decay of Sb 124 . The half life of Sb 124 is 60 days and after it has decayed, arrangements can be made for its reactivation in a reactor. The Research Chemicals Division, Nuclear Corp. of America, Burbank, Calif., has brought out an instrument, the Model BEL 100B Berylometer. This consists of a 5-decade scaler, detector head, and a lead castle for shielding. The sample, metal, powdered rock ore, or beryllium-containing compound to be tested, is placed in a container and inserted into the sample slide. Gammarays from an antimony-124 source interact with the beryllium in the sample, giving off neutrons, which are detected by a scintillation counter. The count rates are compared with samples of known beryllium content. We have no definite information on the selectivity and sensitivity of this procedure, but they should be high. Presumably, new slugs of Sb 124 are available to replace those which have decayed beyond a certain useful level. The steady decay is of no importance in an actual determination, because an unknown is always compared with a standard sample.
1LLCO-WAY iomjJK&cnige DE-IONIZED PURE WATER (LESS THAN 0.5 PPM DISSOLVED SOLIDS)
NOW "ON TAP" THROW-AWAY CARTRIDGE ATTACHED TO FAUCET IS A MINIATURE MIXED-BED lONXCHANGER Ion-exchange is a convenient and lowcost method for purifying water by the removal of all ionizable dissolved solids. Industrial size equipment for this process consists of large tanks with associated valves and piping, and requires periodical regeneration with strong acid and alkali. The ILLCO-WAY Cartridge is simply a small and handy non-regenerable version designed for laboratory use. Tap water passed through the Cartridge (which is a clear plastic tube 2>£" diameter, 19" long) gives up to the "mixed-bed" resins in the tube t h e cation and anion radicals of common dissolved impurities such as various carbonates and sulfates, chlorides, C0 2 , and silica. The effluent is a water of high chemical purity, comparable to triple-distilled (except that ionXchange cannot remove bacteria, pyrogens, or suspended c o n t a m i n a n t s ) . T h e purple-colored resins in the tube change to a yellowish color as the resin becomes progressively exhausted from the top down. When t h i s clear designator of r e m a i n i n g capacity nears the bottom, the Cartridge is simply removed from its holder, thrown away, and replaced by a fresh one. Write for Bulletin CA giving details of construction and methods of use. RESEARCH MODEL UNIVERSAL MODEL CARTRIDGE ONLY CARTRIDGE ONLY Removes all ionizable Removes all ionizable solids including silica solids, except silica and and C(>2. Average in efC0 2 . Suitable fnriiuneriil fluent less than 0.5 ppm pure water needs. total solids. Capacity, 1000 sirains a.-; Capacity, 500 grains as CaCO,, CaCO;;. Flow Rate, 5 gph max. Flow Rate, 5 gph max. Price, 59.75 Price, $12.50 WALL BRACKET with s ip-on connection to water $7.50 MOUNTING FIXTURE, clamp-in type for lincpressure use $12.00 Order from your laboratory Supply House ILLINOIS WATER TREATMENT C O . 840 Cedar St. Rockford, Ml. NEW YORK OFFICE: 141 E. 44th SI., New York 17, N.Y. CANADIAN DIST.: Pumps & Softeners, Ltd., London, Can. Circle No. 36 on Readers' Service Card
ILLCO-WAY
Circle No. 163 on Readers' Service Card
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