V O L U M E 22, N O . 4, A P R I L
1950
23 A
MODEL III POLAROGRAPH MANUAL Ε. Η. Sargent & Co., the manu f a c t u r e r of P o l a r o g r a p h s , offers three different Polaro graphs—the Model X X I Vis ible Chart Recording; the Model X I I Photographic Re cording, and the Model III Manual. T h e Model III Polarograph may be used in any phase of polarography, but it is partic ularly recommended for appli cations to which it is peculiarly suited and in which recording facilities are unnecessary.
The Model III is recommended: (1) In those routine analyses where only one substance is determined and where the step shape approximates a pure form, characteristic of reversible reactions in volving simple ions in fairly substantial concentrations. In such cases, step height may be measured as the differ ence between two points, one on the residual current plateau and one on the diffusion current plateau. For measurements of this type, a simple manual instrument such as the Model III is preferable to a recording Polarograph because of the speed and ease with which it may be operated even by relatively non-technical personnel. (2) In those laboratories where a recording instrument is now in use for several determinations, a Model III may be used for each determination, thus releasing the record ing Polarograph for research purposes and for establish ing the conditions of the routine analyses. (3) In the performance of amperometric titrations. (4) For instructional purposes in educational institutions where the 315 mm. long, readily visible scale and the sim plicity of design make the Model III Polarograph ideal for demonstrations and illustration of the basic circuit employed in Polarographs. Essentially the Model III provides facilities for the incremental application of voltage across the dropping mercury electrode cell and for indicating the resultant current passing through the cell. The cell current is measured by a highly sensitive gal vanometer from which a line light image is transmitted, through a mirror system, to a translucent scale located
SARGENT
above the instrument panel. The scale is 30 cm. long, with circular curvature, to eliminate tangent error. A continu ous selection of bridge voltage from 0 to 3 volts is pro vided, and the selection of output voltage is by rotation of a single dial, this dial reading direct in millivolts per span volt. Current is calculated simply by multiplying scale reading by multiplier reading by sensitivity coeffi cient of galvanometer. To adjust galvanometer sensitivity a ten position Ayrton galvanometer shunt is provided. Galvanometer sensitivity is approximately 0.005 micro amperes/mm. and galvanometer shunt ratios are from 1:1 to 1000:1. A ten turn helical potentiometer serves both for upscale and downscale compensation and for adjustment of the galvanometer zero position. Another potentiometer incorporating a power switch serves to select the desired voltage across the bridge. A panel mounted voltmeter accurate to 1.0% of full scale indicates the voltage established. The instrument is mounted on a cast aluminum base and enclosed in a sheet metal housing provided with a hinged top and finished in black enamel. All controls are mounted on a polished aluminum panel. S-29290 POLAROGRAPH—Manual, Indicating, Model III, Sargent. Complete with three No. S-30858 dry cells, one No. S-29304-A galvanometer lamp, one set No. P.N. 1995 cell lead wires, one No. P.N. 2067 calibrating resistor plug, 250,000 ohm, and cord and plug for con nection to standard outlets. For operation from 115 volt 50 or 60 cycle circuits $360.00
SCIENTIFIC LABORATORY INSTRUMENTS • APPARATUS • CHEMICALS E. H. SARGENT & COMPANY, 4647 W. FOSTER AVE., CHICAGO 30, ILLINOIS MICHIGAN
DIVISION,
SOUTHWESTERN
1959
EAST J E F F E R S O N
DIVISION,
5915
PEELER
STREET, D E T R O I T 7 , STREET,
DALLAS
MICHIGAN 9,
TEXAS
