WE LIVE IN A BAT tery-operated world, yet only a minuscule portion of the power we use actually comes from batteries. That’s a good thing, because it would take about eight AA cells to boil a cup of water. But inefficient as they are, batteries have the key advantage of supplying power wherever and whenever we need it.

Electric batteries may have been in use two centuries before Christ. In 1938 the German archeologist Wilhelm K’f6nig found a small, oddly configured clay jar near Baghdad that he dated to 200 B.C. It had a coiled copper sheet inside and an iron rod extending through the top. When filled with an acid such as vinegar, it could have generated 1.5 to 2.0 volts. K’f6nig thought the mysterious jar must have been used to produce electricity, perhaps for medical treatment, though not everyone agrees with his interpretation.

In any event, the modern history of batteries begins with the Italian scientist Alessandro Volta. In the late 1790s he built the first apparatus for generating a continuous electric current. The voltaic pile (or cell), as it was called, consisted of a series of alternating silver and zinc disks, separated by pasteboard moistened with saltwater. The circuit was completed with a wire connecting the disks at the ends of the stack. In operation, the zinc disks released positively charged ions into the salt solution, while on the surface of the silver disks, hydrogen ions were reduced to hydrogen gas. As this happened, a weak current flowed, gradually declining as the silver disks became fouled with hydrogen.

Volta thought of his apparatus as an “artificial electric organ” that mimicked the anatomy of natural creatures: “The electric organ of the torpedo or electric eel, consists of several membranaceous columns, filled from one end to the other with a great number of plates or pellicles, in the form of very thin disks. …” Others carried the analogizing much further: The German scientist Johann Ritter saw batteries as (in the words of a later historian) “the electrical manifestation of the World Soul,” in which “the duality of the electrical poles governed the eternal oscillations between growth and decay.”

The term battery had been coined by Benjamin Franklin to refer to a collection of Leyden jars, which were essentially large capacitors. It was adopted by later scientists to describe a collection of voltaic cells. The practice of connecting cells in series to boost the voltage continues to this day, most familiarly in the 9-volt battery, which consists of six 1.5-volt cells, as can be revealed by pulling off the battery’s skin. Battery is also commonly used in reference to a single cell.

Telegraphy, developed in the 1840s, was the first major industrial application of battery technology. The earliest step toward our Walkman world came in 1866, when Georges Leclanché of France invented the zinccarbon cell, forerunner of today’s portable batteries.

Leclanché’s battery was a wet cell, requiring a liquid electrolyte (the medium that conducts the ions). It was fragile and had to be kept moist and level, so it was not portable. In 1887 Carl Gassner of Germany developed a dry zinc-carbon cell by using a paste electrolyte made with plaster of Paris and ammonium chloride. The reactants were sealed with pitch in a zinc container, which served as the anode (the part that emits electrons, which are absorbed at the cathode). In 1896 America’s first commercial dry cell, marketed by the National Carbon Company, went on sale.

At last Americans had a portable source of power, but for the first few years, they were not sure what to do with it. Inventors came up with portable fans, a novelty pocket light, and even an illuminated flowerpot. The last of these was invented by an entrepreneur named Joshua Lionel Cowen, who sold the company to his salesman Conrad Hubert and started a successful model-train business that he called by his own middle name.

Hubert, meanwhile, devised the dry cell’s killer application, an “electric hand torch,” or flashlight. He named his company American Ever Ready. Flashlights proved enormously popular, which was good news for dry-cell manufacturers, such as the National Carbon Company. NCC boughl American Ever Ready in 1914 and began selling bott flashlights and batteries under the Eveready brand.

Unlike most technologies, flashlight batteries changed little during the first half of the twentieth century. Lifespans remained limited, and leakage of corrosive fluids was a persistent problem. During this period the main progress in battery technology came in high-end applications, such as military devices.

The first major advance in flashlight batteries came in 1959, when Eveready introduced the alkaline battery. As developed by Lew Urry, it used a strong base as its electrolyte instead of the acid found in previous cells. Urry’s design lasted five to eight times as long as the zinc-carbon cells of the day. Today’s alkaline cells have a lifespan 40 times that of the earliest ones.

Urry’s first demonstration of his alkaline battery went very much like a television commercial. He took a pair of toy cars, put his prototype battery in one and a zinccarbon cell in the other, and invited an Eveready vice president to the company cafeteria to watch them in action. “Our car went several lengths of this long cafeteria,” Urry recalled a few years ago. “The other car barely moved. Everybody was coming out of their labs to watch.” Murky flashlights and fading transistor radios soon passed into history as new portable gadgets were invented: tape recorders, televisions, electric razors. With the advent of alkaline cells, batteries had finally achieved the ultimate technological success: becoming dependable enough to be taken for granted.

The century that just ended saw many new materials adapted for battery use, including mercury, silver oxide, nickel-cadmium, lithium, and metal hydrides. As with Freon and leaded gasoline, whose histories are detailed elsewhere in this issue, little thought was given at first to what would happen when millions of tons of these substances were discarded into the environment. Recently mercury has been eliminated from batteries because of its toxicity; cadmium may be next.

Many of today’s batteries are rechargeable, including the lithium-ion cells used in power-hungry applications like video cameras, laptop computers, and cell phones. (Rechargeable batteries have been around since Volta’s day, but until late in the nineteenth century there was nothing to charge them with except another battery.) Different types of cells exist for power requirements ranging from 25 microwatts (for a cardiac pacemaker) to 50 kilowatts (for certain military uses). Some even use air as an electrolyte. Amid all this high technology, the humble zinc-carbon battery is still with us. For devices used only occasionally, such as flashlights, they can be more cost-effective than other types. And these days they seldom leak.