Alkaline zincate cells have copper for the positive, and iron for the negative electrode. The electrolyte is composed of sodium, or potassium, zincate. Cells of this type are used to some extent for traction purposes.
In addition to the above there are some special forms of cell which do not belong to the four preceding types.
Ans. In the Plante type the lead is chemically attacked and finally converted into lead peroxide, probably after it has gone through several intermediate changes. The plates are all formed as positive plates first and then all that are intended for negative plates are reversed, the peroxide being changed into sponge lead.
[Illustration: FIGS. 1,055 and 1,056.—Willard plates; fig. 1,055, negative plates; fig. 1,056, positive plates. Both positive and negative plates are of the Planté type, made from one integral piece of rolled lead. These are grooved plates. The projections are tapered, that is, they are wider at the base than at the surface, for strength. The center web of each positive plate is tapered from the top of the plate downward to secure uniform distribution of the current all over the surface of the plate.]
[Illustration: FIG. 1,057.—Wood separator for spacing the plates, as used in the Willard storage cells.]
[Illustration: FIG. 1,058.—Positive plate.]
[Illustration: FIG. 1,059.—Perforated rubber separator.]
[Illustration: FIG. 1,060.—Wood separator.]
[Illustration: FIG. 1,061.—Negative plate.]
[Illustration: FIG. 1,062.—Hard rubber cover.]
[Illustration: FIG. 1,064.—Pillar connecting strap.]
[Illustration: FIG. 1,065.—Hard rubber jar.]
[Illustration: FIG. 1,066.—Complete element.]
[Illustration: =Figs. 1,058 to 1,066.—Parts of the Willard "Autex" automobile cells.=]
=Ques. What is done to make the Plante plate more efficient?=
Ans. The surfaces are finely subdivided, the following methods being those common: scoring, grooving, casting, laminating, pressing, and by the use of lead wool.
=Ques. Describe the Faure or pasted type.=
Ans. This form of plate is constructed by attaching the active material by some mechanical means to a grid proper. The active material first used for this purpose was red lead, which was reduced in a short time to lead peroxide when connected as the positive or anode, or to spongy metallic lead when connected as the cathode or negative, thus forming plates of the same chemical compound as in the Plante type.