. A treatise on electrolysis and its applications to therapeutical and surgical treatment in disease . ained by other observers ongalvanometers of any construction, but graduated in absolute units. Anidea of the peculiarities of the absolute galvanometer,1 contrasted withthe galvanoscope, will be obtained by a glance at the diagram. It 1 We object to the use of this term, absolute galvanometer, because the meas-urements obtained by the use of galvanometers of any description are simply com-parative and not absolute. - The galvanoscope is strictly speaking a galvanometer which does not. neces-s
. A treatise on electrolysis and its applications to therapeutical and surgical treatment in disease . ained by other observers ongalvanometers of any construction, but graduated in absolute units. Anidea of the peculiarities of the absolute galvanometer,1 contrasted withthe galvanoscope, will be obtained by a glance at the diagram. It 1 We object to the use of this term, absolute galvanometer, because the meas-urements obtained by the use of galvanometers of any description are simply com-parative and not absolute. - The galvanoscope is strictly speaking a galvanometer which does not. neces-sarily, show variations in the strength of the current, but simply its direction. 260 ELECTROLYSIS. (Fig. 49) represents the dial of an instrument divided in its upper halfinto degrees, in its lower half into milliamperes. The principle that theangle of deflection does not increase proportionally to the current strength,is ilhistrated by the fact that, whilst for instance a current of 30 milliam-peres deflects the needle to about 45°, a current of 150 milliamperes isrequired to deflect it to 70°.. Fig. 49. The simplest method of graduating a dial of a galvanoscope into sub-divisions of an ampere, is to place the instrument in the same circuit asa tangent galvanometer of which the reduction factor is known (or of agalvanoscope already so graduated) along with a constant cell and a boxof resistance coils. By means of the latter the current is modified so asto produce a deviation of 1, 2, 3, etc., to 20 or more milliamperes asmeasured on the standard galvanometer. The corresponding deviationsof the galvanoscope are indicated on the dial, and their value in milliam-peres written down. In the absence of a standard galvanometer, a large standard cell istaken of known electromotive force. The most convenient for this pur-pose is the Daniel, in which the sulphate of copper is replaced by nitrateof copper. The electromotive force of such a cell is as near as possibleone Placing
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