The Daniell Cell Charger

Radio Record, Volume II, Issue 21, 7 December 1928, Page 28

The Daniell Cell Charger

N our issue of November 11, 1927, "Megohm" described a charger comprising Daniell cells. A correspondent has been using this but meets with trouble. "I have installed the Daniell cells on accumulators as the R.R. article describes. . I find that the ‘gincs are used very badly within a month. © Since then have. brought the Epsom ‘solution from half saturated ‘to 20z. for the six pots. (4pt. capacity each approximately) still they. seem to eat away quickly. I changed to 1-80 of sulphuric acid with new zincs, and they were treated the same. Should the zincs last very long? Bluestone seems. to go into the porous pots quickly. ' Questions.--(1) How can I check the bluestone from cree~" 3 too much

to make the zines last longer; using either Epsom or sulphuric in pots. . (A,) Bluestone and numerous other "salts" exhibit a peculiar action. If a piece of bladder similar to the material used for sausages, is filled with a solution of bluestone it can be sealed up and will be perfectly watortight. If, however, this ‘container, tied up tightly is lowered into a vessel of water, in a few hours the water will be found to be turning blue, and in a day or'so the two solutions inside and outside the bladder will be of the same strength. This is known as a "colloidal" action. The bluestone has passed through the membrane. ~ The same action takes place in a Daniell cell. There is no actual preventive but the action can be retarded a great deal by arranging so that the two acid solutions inside the porous pot and outside are equal in strength. (2.) Should Daniell cells show 6 volts, and when 4 jars show 4 volts,

should the 4 give same amperage as accumulators to light a torch bulb? This in view of voltmeter giving out. (A.) The true Daniell cell of bluestone and 10 per cent. solution of sulphuric acid should show 1.8 to 2 volts per cell. The amperage should be from 15 to 30 on dead short, depending on the size of copper electrode and strength of acid. A torch bulb-only tikes .8 ampres at 4 volts.

disconnecting? io (A.) No, The zines should always be P lifted out of solution When not in use. You ask about the life of zincs. I prestime you: hive got these amalgamated. If you haven't, get a small quantity of mercury and ‘put in the bottom of:each porous pot. About half a thimbleful to each pot. » This will coat the zincs with mercury, and prolong their life. — ) (8) Is any harm done to charger in