The Spiral Coil Voltameter
Harris J. Ryan · Transactions of the American Institute of Electrical Engineers · 1889
During the present year at the Physical Laboratory of Cornell University, the copper voltameter has been used somewhat ex- tensively in laboratory practice by students for calibrating Thom- son graded galvanometers, tangent galvanometers, and other elec- trical mneasuring inistruments where a single determination suffices as a calibration.For practical instruction students are niade to check their results on a Thomson gravity balance, arid by means of the large galvanometer at the Magnetic Observatory.The plate form of copper voltameter has been thoroughly and admirably investigated by Mr. Thomas Gray,' of the Physical Laboratory of the University of Glasgow.We are indebted to Mr. A. W. Meikle and to Lieutenant Anderson' for clear descriptions, based upon the results of AMr.Gray, for the use of this form of voltameter, whereby determinations may be made so accordant, that one can scarcely think of more to be desired.With all this, however, it has been our experience that students are slow to obtain accordant results when making their first attempts to follow Mr. Gray's methods.It seemed desirable to make use of a form of voltameter that required the least con- sistent time and care to construct and prepare for operation.Again, there should be a wide allowable range of current density, through which deposits would be as firm and adherent as possible.It was with a view of realizing this that we finally adopted and made use of the spiral coil form herein described.A wire coil as a cathode seemed to present many advantages.Wire of high conductivity, good for this purpose, is generally 1 Phil.