. Practical physical chemistry . fordirecting the current through one or other of two circuitsor for reversing the current. When used for the formerpurpose, the poles of the battery are connected by means ofthe terminals 2 and 5 with the corresponding mercury cups,and the wires of the two circuits are connected respectivelywith the terminals i and 6, and 3 and 4. By means of arocking bridge consisting of two T-shaped pieces of copper rodconnected by an insulating bar of glass or ebonite, the currentcan be sent through one or other of the two circuits. When inthe position shown in Fig. 58, A, t
. Practical physical chemistry . fordirecting the current through one or other of two circuitsor for reversing the current. When used for the formerpurpose, the poles of the battery are connected by means ofthe terminals 2 and 5 with the corresponding mercury cups,and the wires of the two circuits are connected respectivelywith the terminals i and 6, and 3 and 4. By means of arocking bridge consisting of two T-shaped pieces of copper rodconnected by an insulating bar of glass or ebonite, the currentcan be sent through one or other of the two circuits. When inthe position shown in Fig. 58, A, the current, will be sentthrough the circuit connected with the terminals 3 and 4 ; and 172 PRACTICAL PHYSICAL CHEMISTRY when the bridge is thrown over so that the ends dip into themercury cups i and 6, the current will be sent through thecircuit connected with these. When the key is to be used for reversing the current,the mercury cups i and 4, and 3 and 6 must be connectedby two insulated copper wires (Fig. 58, B). The battery. % p % ® / K (D // \S // ®- tD B Fig. 58. is again connected with the terminals 2 and 5 as before, andthe circuit through which the current is to be sent, either withthe terminals i and 6, or 3 and 4. When the ends of thearched portions of the bridge are in the cups i and 6, thecurrent will pass in one direction, and when they are in thecups 3 and 4, it will pass in the opposite direction throughthe circuit. The ends of the rocking bridge should beamalgamated. CONDUCTIVITY OF ELECTROLYTES 173 On account of the absorbing power of platinum black, theremoval of the last traces of platinizing liquid and occludedchlorine sometimes causes difficulty. It can best be effectedeither by placing the electrodes in a solution of sodium acetateor dilute sulphuric acid and passing a current for about quarterof an hour, with reversal of the current every minute; or byconnecting the two electrodes together and making them thecathode in a solution of dilute sulphuric ac
Size: 2236px × 1118px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpublisherlondonnewyorklongm
