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STORAGE-BATTERY

1833

STORM

Stor'age=Bat'tery, a form of voltaic bat- f tery in which the energy, when once used, may be replaced by a process known as charging.

Like almost every other form of voltaic cell, the storage-cell consists of two conductors of the first class and one of the second class. In this case the conductors of the first class are lead and lead-peroxide, while the conductor of the second class is a solution of sulphuric acid.

This form of voltaic cell was devised in 1860 by Plante, a Frenchman. He started with two lead plates in sulphuric acid. By passing an electric current from one of these plates through the acid to the other, he succeeded in oxidizing the anode, while the cathode remained metallic lead. By frequently changing the direction of the current passed through the cell the lead-plates were rendered porous and spongy and made to present a large surface. This process is known as forming the plates. Finally a current is passed through the cell in one direction until one plate is thoroughly oxidized, while the other remains spongy, metallic lead. This process is known as charging the cell.

The charging simply restores the oxygen to the positive plate and removes the oxygen from the negative plate. Voltaic cells are divided into two classes according as they require charging or not. Those which require charging are called secondary cells; while cells of the Daniell or Bunsen type, which are made up once for all and continue to work until one of the electrolytes or one of the electrodes is exhausted, are called primary.

In 1881 Faure devised a process of putting a paste of red lead (lead-peroxide) on the positive plate and shortening the process of forming. But in the very best cells of recent years there has been a partial return to the process of Plante. When a storage-cell is being used, the current in the cell flows from the spongy bed-plate to the plate which is covered with lead-peroxide (Pbo2). The result is that the former is oxidized and the latter reduced from lead-peroxide to lead-oxide. When all the peroxide is used, the cell must be charged again.

From the preceding it is evident that what is stored up in this cell is chemical energy, and not electricity, as is sometimes popularly supposed. The great merit of its storage-cell is its high electrical pressure, more than two volts, combined with a very low internal resistance. This low resistance permits the use of enormous currents without wasting much energy inside the cell.

Storage-cells are used for an endless variety of purposes; but their principal use may be reckoned as that of a "booster" in helping the dynamo during the busy hours at the electric-light station and the street-railway power-house. Many tons of storage-

cells are employed also in driving automobiles and small launches. Storage-cells are often called accumulators.

Stork,  a   large, heron-like bird with bill much longer than the head and very stout at

the base. The common migratory stork of Europe is the be s t-known mem-ber of the family. It is a friendly bird, nesting on housetops, old chimneys and steeples, as well as on tall trees, and is regarded as a bird of good omen. It breeds in Holland and Germany, but not in France, Italy or Russia. It is about three and one half feet long, white, except the wings which are partly black. In the autamn these birds gather in large flocks and migrate to Africa, where they spend the winter. They frequent marshy places and feed on frogs, fishes, snakes, slugs, younj* mammals and insects. There are about 20 species in tropical an$ temperate parts of the world. There is only one form that breeds in North America, the wood-ibis, which is about the length of the European stork. It is mainly white, with glossy black on the wings and tail. The head and upper part of the neck have no feathers and are of a dusky color. It breeds as far north as the southern limit of Illinois, and is an occasional summer-visitor farther north. See ADJUTANT-BIRD. Storm, a violent disturbance of the weather, especially as regards wind and rain. By simultaneous observations of the barometer it has been found that the atmosphere of the earth is made of regions of high and regions of low pressure or, as they are called by meteorologists, anticyclones and cyclones respectively. It is the cyclones or regions of low pressure, rotating in the northern hemisphere in a direction contrary to the hands of a watch, that constitute most of our storms. In the United States these cyclones originate mostly in the region west and northwest of the Mississippi — between the Rocky Mountains and the Mississippi River or in the region about the Gulf of Mexico. Many of the storms of the Atlantic originate about the Gulf of St. Lawrence; while the storms of Great Britain take their rise mostly in the mid-Atlantic. From knowing the general trend and rate of motion of these cyclones and studying

STORK