No. 74. A zinc rod, about ⅜ in. in diameter, like those used in Leclanché cells.
No. 75. A sheet copper plate for the two-fluid cell (C, [Fig. 87]). This is 2 in. wide; it nearly surrounds the porous cup, and is supported upon the edge of the tumbler by a narrow strip, A, with which connections are made by spring connectors (No. 54).
No. 76. One strip of sheet iron, 4 in. by ½ in.
No. 77, 78. Two strips of sheet lead, 4 in. by ½ in.
No. 79. A resistance coil ([Fig. 94]). The coil is made of No. 24 insulated copper wire; it has a resistance of 2 ohms (nearly) and is fastened to a cardboard base. It is so arranged that either one or two ohms can be used at will.
No. 80. A Wheatstone's bridge ([Fig. 103]), including a scale (No. 100). The aluminum straps, 1, 2, 3, are fastened to a neat wooden base, 10 in. long by 2 in. wide. A No. 28 German-silver wire is used for the bridge.
No. 81. A piece of No. 30 uncovered German-silver wire, 2.1 meters long, used for resistance ([Fig. 96]).
No. 82. A piece of No. 28 uncovered German-silver wire, 2.1 meters long.
No. 83–85. Three plate binding-posts, consisting of bent straps of sheet aluminum (X, Y, Z, [Fig. 96]).