Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . is used, the current acquires sohigh an intensity that its power of producing ignitionis diminished, as it becomes capable of traversing apretty fine wire without obstruction. 57. Either of the batteries of single pairs, whichhave been described, have sufficient power to ignitea fine wire of iron, or other metal, through which thecurrent is made to pass. This effect is most easilyproduced in those metals which offer the greatestresistance, not only to
Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . is used, the current acquires sohigh an intensity that its power of producing ignitionis diminished, as it becomes capable of traversing apretty fine wire without obstruction. 57. Either of the batteries of single pairs, whichhave been described, have sufficient power to ignitea fine wire of iron, or other metal, through which thecurrent is made to pass. This effect is most easilyproduced in those metals which offer the greatestresistance, not only to the passage of electricity, butalso to that of heat; hence a larger wire of platinummay be ignited than of perhaps any other metal, asit is a poor conductor both of electricity and ofheat. A steel wire, when intensely heated in thisway, burns with beautiful scintillations. The shorterand finer the wire, within certain limits, the greateris the effect produced. 58. Fig. 25 represents an instrument, by means CONDUCTION OF GALVANISM. 37 of which the current may be made to pass throughvarious lengths of wire. The sliding arms may be Fig. fixed in a variety ofpositions, so thattheir extremities,holding the wire,may be at differentdistances apart. Afine wire, if not toolong, thus interposedin the course of apowerful current, is4^ <^ immediately fused or deflagrated. This instrument has been used todetermine the conducting power of metals, by pas-sing the current of a constant battery through aninstrument capable of measuring its magnetizingpower, and then also opening a collateral circuit tothe same current through a certain length of finewire, first of one metal, then of another. The in-strument employed to measure the magnetizing pow-er was the Magnetometer^ which will be describedhereafter. In this instance, the current is divided:a portion of it, equivalent to the conducting powerof the metal under experiment, passes through thefine w4re; and the measuring instrument, th
Size: 1738px × 1437px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1850, booksubjectmagnetism, bookyear18
