=Ques. Describe the behavior of the electrolyte during discharge.=
Ans. There is a definite change in the density of the electrolyte for a given amount of discharge.
The density of the electrolyte is, therefore, one of the best indications of the state of charge, provided, of course, no internal discharge due to local action takes place. If, when the cell is charged, it show a density of 1.200, and when discharged 1.130, the difference .07 represents the total charge. If at any time the density be 1.165, then just one half the amount of capacity has been taken from the cell.
It is necessary to stir the electrolyte well, in order for these observations to be reliable.
If the discharge has taken place at a high rate, the cell must stand for an hour or more before the electrolyte will completely diffuse so that the density readings are correct.
[Illustration: FIG. 1,127.—Electric Storage Battery Co., arc lead burning outfit. In assembling a storage battery element, a negative plate is laid down with a separator on it, then a positive plate, separator, negative plate, etc. The plates are so placed that all the lugs of the positive plates are on one side and all the lugs of the negative plates are on the other side. A strip, consisting of flat strips of lead or lead alloy, having rectangular openings in it of the same dimensions as the cross section of the lug of the plates, these openings being spaced to register with the lugs, is then placed over the plate lugs of the positive plates and a similar strap is placed over the lugs of the negative plates. The lugs are then burned into integral union with the straps.]
Ans. Boiling means the rapid evolution of gas when a cell is nearly charged.
Ans. The amount of sulphate to be converted into peroxide becomes less and less as the charge progresses and the plates therefore become virtually smaller, so that the current becomes too large for the work demanded of it. The result is, that part of the current not actually used in the formation of peroxide decomposes the electrolyte into its constituent elements.
=Ques. Why do the gases evolved produce a less milky appearance of the electrolyte when a battery has been in use for a considerable time?=