An experimental storage battery, having qualities of interest, and at least remotely suggestive of commercial possibilities, may .be constructed at a cost of a few cents, as follows:

Provide four strips A, B, C, D, of thin cloth (calico will answer), the strip A being 20 feet long and 4 inches wide, the strip B 18 feet long and 3 inches wide, the strip C 10 feet long and 4 inches wide, and the one designated as D 9 feet long and 3 inches wide. Procure an ordinary battery jar, E, of cylindrical form, a pound of commercial flake graphite, a few gum bands, and two pieces of No. 30 bare copper wire, one (G) being 20, and the other (H) 10 feet in length. These parts and materials, together with a carbon rod F of the kind used for are lighting, comprise everything needed except water and enterprise.

Spread out the strips B and D, shower them liberally with water, and dust the graphite upon them. Then stroke them off with the hand. This will remove all excess of graphite, and leave them shining like strips of new tin plate. A single coating of the graphite upon one face of the cloth is sufficient.

Spread out the strip A, which remains uncoated, and lay tin-strip B centrally upon it, so as to leave exposed all margins of the strip A, its ends extending equally and in opposite directions beyond the ends of the strip B. Extend the wire G along the strip B from one of its corners to the opposite corner, the wire thus being slightly oblique relatively to the strip, and extending a couple of feet beyond one corner. Next place in position the strip C. which remains uncoated, centering it lengthwise in relation of the other strips, and bringing its longer edges flush with those of the strip A. Place the strip I) on the strip C, leaving all margins equally matched. Stretch the wire H along the strip D, from one corner to the corner opposite, the wire being slightly oblique to the strip, so as to cross the wire G and leaving a foot of the wire H projecting.

Wind the projecting end (2 feet long) of the wire G tightly around the carbon rod F, and lay the rod squarely across the adjacent end of the strip B, so as to make good contact with the graphite. This will leave a foot of the strip A extending from the rod F. Bend this extending portion back over the rod so as to cover it, and then, using the rod F as a spool, roll it along. pressing it down hard; and thus wind tightly upon it all of the strips and both of the wires, so as to form a hard roll having generally the appearance of a solid white cylinder. Stretch two or three rubber bands around the roll, so as to hold all of its parts rigidly in position. Find the projecting end of the wire H, and leave it exposed. Set the roll into the jar, so that the exposed portion of the wire H and also a portion of the carbon rod F extend upwardly. Now fill the jar with water, preferably submerging the roll to within half an inch of its top.

Fig. 213 - Storage battery without chemicals.

This completes the battery. In some instances it may be improved by making the strips A C of cloth thicker than above designated.

The battery may be charged from an ordinary dry cell, by connecting the zinc shell of the dry cell with the carbon rod of the storage battery, and the carbon of the dry cell with the protruding wire of the storage battery. After being thus charged for fifteen or twenty minutes, the storage battery may be disconnected, after which it will yield, for a few minutes at least, a current not differing greatly from that with which it was charged, and adequate to operate a telegraphic sounder or an electric bell. If the energy of the battery be conserved by leaving the circuit open, the charge may last for several days. Like other storage batteries, this one. after being partially exhausted, will recuperate to some extent if the circuit be left open, though of course the total energy it gives out can never exceed that with which it is charged.

This device is in every sense a true "gas" battery as well as a storage battery. While it is being charged, the current sent through it disintegrates a portion of the water into its two component gases. The hydrogen, being disengaged throughout the entire length and breadth of the graphite coating carried by the strip B, is simply absorbed or occluded within the pores of the cloth, and thus effectively held as a free gas in a state of captivity. The oxygen, being in part in its allotropic form of ozone, is similarly collected and held in the strip C. The strip A, holding the hydrogen, being twice as long as the strip C holding the oxygen, is adapted to hold twice as much gas, thus compensating for the difference in volume between the hydrogen and oxygen. Both gases, being freshly liberated, are in their nascent state and eager to recombine. After the charging is completed, therefore, and a conducting path is established from one of the coated strips to the other, the gases recombine, forming water, and in so doing they generate an electric current flowing in a direction opposite to that of the current previously used for breaking up the water and forming the gases.

It is a fact not generally known that if a quantity of hydrogen and a quantity of oxygen be subjected as nearly as practicable to the same physical conditions, they will present relatively to each other a difference of potential of about a volt and a half.