Leclanche' is the technical name for (credit to the inventor Georges Leclanche' in 1866) the dry cell. These 1.5 V cells were a safer alternative to the wet cell (lead-acid) which were common as "A" battery or tube filament battery. Their shortcoming is that they are Primary Cells. This means they cannot be recharged like the wet cells. These cells had a carbon positive post, surrounded by a manganese dioxide paste (electrolyte) surrounding the post. Holding the paste was a metal can or the negative post. Eveready marketed the cell as the number 6. Four were needed hooked up in series to provide adequate filament voltage for the UX201 and similar battery tubes. According to Eveready specifications, if the load was 0.6A (1-2 UX201 tubes connected in series) and I ran the cells 2 hr/da, with a dropout voltage of 30% of total, the cell would last about 50 hours. Most radio sets had 3 to 5 UX201s so the life would be shorter so often these cells were wired in parallel for longer life. These cells became popular for education and industrial purposes because of the large current capacity. Improvements in primary and rechargeable (secondary) battery technology eventually made this cell obsolete.