A text-book of physics, largely experimentalOn the Harvard college "Descriptive list of elementary physical experiments." . n packedin crushed carbon mixed with peroxide of cell polarizes rapidly when the circuit is closed, but isvery useful in furnishing occasional currents of short dura-tion, such as are needed for ringing door-bells and soundingalarms. Storage-cells usually have for the positive electrode,plates, or grids, of lead loaded with oxides of lead, andfor the negative electrode similar plates with less oxide oflead. These plates are placed in sulphuric acid of a cer
A text-book of physics, largely experimentalOn the Harvard college "Descriptive list of elementary physical experiments." . n packedin crushed carbon mixed with peroxide of cell polarizes rapidly when the circuit is closed, but isvery useful in furnishing occasional currents of short dura-tion, such as are needed for ringing door-bells and soundingalarms. Storage-cells usually have for the positive electrode,plates, or grids, of lead loaded with oxides of lead, andfor the negative electrode similar plates with less oxide oflead. These plates are placed in sulphuric acid of a certainstrength, contained usually in a glass or hard-rubber jar. In the charging of such a cell a current is sent infrom some dynamo (see Chap. XXXIII) by way of thepositive electrode and out by the negative electrode. Oxy-gen is thus sent to the positive plates, adding to the oxideswhich are already there, and meanwhile hydrogen, going tothe negative plates, unites with and takes away some or allof the oxygen there. The original difference between thepositive and the negative plates is thus increased. When 474 Fig. 254. the charging is nearly complete, bubbles of hydrogen nolonger absorbed by the oxygen at the negative plates, risein large quantities from those plates to the surface of theliquid. The method of arrangement of the plates in a storage-cellmakes them equivalent to two very large plates, one posi-tive and one negative, veryclose together (see Fig. 254,which shows the top view ofa cell). This makes the so-called resistance (see ) of the cell verysmall, and it is for thisreason, mainly, that a stor-age-cell, newly charged, cangive a much more powerful current than a PoggendorrTcell, for example. After a time of use, the storage-cell becomes reduced incharge, and the current from it speedily grows cell is said to be run down, and must be chargedagain. The positive plates of a storage-cell can usually be dis-tinguished from the negative by th
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishe, booksubjectphysics
