Ques. What causes boiling?
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?
Ans. The plates are better formed; consequently a larger charging current can be used without producing "boiling".
Fig. 1,128.—Hydrogen gas generator for lead burning. A complete lead burning outfit consists of the following parts: 1, hydrogen gas generator; 2, trap for cleaning the gas and for preventing the flame getting back in the generator; 3, air pump; 4, air tank; 5, blow pipe; 6, lead burner's mixing tee; 7, length of 150 feet 5/16 inch soft rubber tubing. When the generator is to be used for lead burning, connect up the different parts of the apparatus as shown. Fill the trap 2/3 full with water and be sure to connect the gas generator to the nipple on the bottle marked B. The stop cocks N and C must be closed. See that the rubber plug at D is secured in place. Put the required amount of zinc in the opening at H. (No. 1 generator requires: 15 lbs. zinc, 9 gals, water, 3 gal. vitriol. No. 2 generator requires: 20 lbs. zinc, 15 gals. water, 5 gals. vitriol). After putting in the zinc, add the water and then the sulphuric acid, and note that the water must always be put in before the acid. When making the connection be sure that there are no low points in the hose between E and N, as water is liable to accumulate at these low places, which will make the gas damp which is detrimental to the burning. If water get into the line, kink the hose between F and B, detach the hose at E and blow out the water with air by opening the cocks, N, C and V. The length of the hose between T and X must not be longer than five feet as the cocks N and C must always be within the reach of the man who is using the flame. When ready to use the flame, open N which allows the hydrogen gas to escape. Light the same with a match and adjust the air cock C until the desired flame is obtained. Different classes of work require different flames, which can be obtained by changing the tips and by varying the amount of gas and air with the cocks N and C. When the generator is laid up for the night, or when the charge is exhausted, pull the hose off at F and draw off the solution by removing the plug at D. The generator should then be thoroughly washed by pouring water in A.
Ques. What may be said of charging a battery as quickly as possible?
Ans. As a general rule, such a procedure should not be adopted unless the battery be thoroughly discharged.
Ques. What precaution should be taken?