An Elementary Handbook of Physics (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1871 Excerpt: ...a "Grove" and a "Bunsen" is the substitution of a carbon cylinder for the platinum plate. The general structure, action, and results are the same in both. The carbon is outside and the zinc inside, because it is an advantage in point of power to have the positive element within the negative, for the same reason that a wire conducts the better for being thick. If the currents proceed from each point of an outer circle to the centre they must get crowded together, interfere with, and partially destroy each other; while if they proceed from the centre outward, they have more and more room for their action. Therefore it is greatly preferable to have the positive element, from which the currents proceed, in the centre, and the negative one outside it. Fig. 105 shows a Bunsen's celL The rod or bar of zinc a is in the centre, surrounded by the cylinder of carbon 6. Fig. 104 shows the same cell from above. A Grove's cell is square, a Bunsen's is circular. But the same objection that exists against the platinum as an element--i.e., the expense--also exists against the use of carbon when made into hollow cylinders. Carbon itself is not expensive, but to make it into cylinders is difficult and costly, and it is found in practice that it is really cheaper to make two cells having a bar of carbon inside a cylinder of zinc, than one having a cylinder of zinc within a cylinder of carbon; in addition to which, the hollow cylinders of carbon are much more liable to be fractured than the solid bars. This has led to the modification of Bunsen's battery in common use in England, which consists of solid bars of compressed carbon as the negative element, and cylinders of amalgamated zinc as the positive. In all other respects the arrangements are exactly as t...