The superiority of the storage cell over any other form of battery is universally recognized. The dry cell has an E. M. F. of only 1.5 volts and deteriorates rapidly with age. The E. M. F. of a storage cell is 2 volts, or 33 1/3 per cent higher. Storage cells will operate almost any electrical device with increased power over any other form of battery. A wireless set will send farther, lamps will turn steadier and a motor will give more power. [Illustration: FIG. 38.—Showing how to charge a Simple Storage Cell composed of two Lead Plates immersed in Sulphuric Acid by connecting it to two Bichromate of Potash Cells.] If properly cared for, a storage cell will last indefinitely. It may be recharged an unlimited number of times and is exactly as good as new each time. A dry cell must be thrown away when discharged. Storage cells are rated by their output in *Ampere Hours.* An *Ampere Hour* is the amount of current represented by one ampere flowing for one hour. A 10 ampere hour cell will give 2 amperes for five hours, 1 ampere for 10 hours, 1/2 ampere for 20 hours, etc. The ampere hour capacity of a cell divided by the amount of current being used will determine how long that current can be drawn before recharging is necessary. Storage cells may be recharged from any source of *direct* current, that is, from the lighting circuit, in series with a lamp, from a small shunt wound dynamo, from dry cells or other primary batteries, or from alternating current by using a *Rectifier*. An Experimental Storage Cell. Storage cells consist of lead plates immersed in an electrolyte of dilute sulphuric acid. Cut two strips, one inch wide and five inches long, out of sheet lead about one-eighth of an inch thick. Attach a wire to each one of the plates and then immerse them in a jar full of *electrolyte* composed of: 1. Ten parts of water. 2. One part of sulphuric acid. Connect the wire leading from the plates to a voltmeter and you will notice that the pointer will not move away from zero. Disconnect the wires and mark one plate as the *positive*, by means of a little cross; mark the other plate *negative*, with a straight line. Connect two good bichromate cells in series and lead the positive terminal to the lead plate marked with a cross. Connect the negative pole of the battery to the other lead plate. Bubbles of gas will immediately begin to arise from the lead plates. Let the batteries remain connected for about five minutes and then remove them. If you then connect the two lead plates to the voltmeter again you will find that the needle now swings nearly to two volts. You will also find that your storage cell, for the two lead plates are now a storage cell, will also ring a bell or run a small motor for a few seconds. The two lead plates became *charged* when the current from the bichromate cells was passed through them. This little experiment illustrates the principle of the storage cell very well.