Electrical measurementsA laboratory manual . hen polishing thor-oughly with glass paper and washing in a rapid streamof water. They may then be rubbed with a cleancloth. On removing from the electrolytic cell, wash atonce thoroughly in water containing a few drops ofsulphuric acid, finally in distilled water, and dry on aclean blotting-pad. The plate may then be held beforea fire and carefully warmed. It must not be weighedtill it has cooled. For large currents a rectangular glass or earthenwarevessel may be used to contain the solution, and the plates 1 A. W. Meikle, The Electrolysis of Coppe
Electrical measurementsA laboratory manual . hen polishing thor-oughly with glass paper and washing in a rapid streamof water. They may then be rubbed with a cleancloth. On removing from the electrolytic cell, wash atonce thoroughly in water containing a few drops ofsulphuric acid, finally in distilled water, and dry on aclean blotting-pad. The plate may then be held beforea fire and carefully warmed. It must not be weighedtill it has cooled. For large currents a rectangular glass or earthenwarevessel may be used to contain the solution, and the plates 1 A. W. Meikle, The Electrolysis of Copper Sulphate, Physical Soc. of Glas-gow University. MEASUBEMENT OF CURBENT. 163 may be of the shape shown in Fig. 78in spring clips on oneside, the anode and cath-ode plates alternating,one set connected by theclips on one side and theother set on the plate may then belifted out and cleanedseparately. The follow-ing table is given by , connecting thearea, of the plate, the tem-perature, and the electro-chemical equivalent:. Sq. cms. of cathode 12° C. 23° C. 28° C. per ampere. 50 .0003288 .0003286 .0003286 100 .0003288 .0003283 .0003281 150 .0003287 .0003280 .0003278 200 .0003285 .0003277 .0003274 250 .0003283 .0003275 .0003268 300 .0003282 .0003272 .0003262 The process of obtaining the current from the weightof copper deposited in an observed time is the same asin the case of silver. The following solution for a copper voltameter is saidto give good results: ^ Copper sulphate 15 gms. Sulphuric acid 5 * Alcohol 5 Water 100 ^Electrician (London), May 19, 1893. 164 ELECTRICAL MEASUREMENTS. This can be used with a current density from amperes per square decimetre. 80. To find the Constant or Reduction Factor ofany Current Meter by Electrolysis. — If the currentsto be measured by the instrument in question do notmuch exceed one ampere, the silver voltameter is to bepreferred; but for currents in excess of one ampere thecopper voltameter ma}^ be used
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Keywords: ., bookcentury1800, bookdecade1890, bookpublisherbosto, bookyear1895
