Bought a box lot of old camera equipment at an auction a week or so ago, box, bellows Polaroid ect. Amongst the equipment, I found a Whitehouse Beacon-II 127 camera, circa 1947-1955. . .
Along with the camera a Beacon Flash synchronizer was there. Playing with the flash I found these batteries still in the unit..... VERY very little leakage and the contacts were in great shape !!
I put a meter on the AA's expecting them to be completely drained and found them to still have .7 and .8 V Dead no doubt but I expected them to be at zero. None the less I was amazed that the batteries didn't leak massively and corrode the whole unit.

Those batteries are older than I am! It sounds like they were used only gently before the flash was stored.

Most non-rechargeable batteries leak when completely depleted, especially if depleted quickly, which causes heat expansion. Today's alkaline batteries are designed to leak so they don't swell and get stuck in tubular battery compartments like flashlights.

I have a Sennheiser wireless mic system. The transmitter drains a pair of AAs in about five hours, and they will leak if I don't remove them immediately after use and throw them away. I've cleaned contacts in that thing several times when my wife and kids used it for a project and forgot to toss the batteries.

Battery compartment contacts can be cleaned most effectively with a 1:1* solution of vinegar applied to a rough cloth (*2.5% acetic acid when diluted 1:1 with water). After wiping with diluted vinegar, quickly use another cloth moistened with distilled water to remove the residue. Then take it outdoors and blast it with DeoxIT D5S-6-LMH Contact Cleaner Spray. That's the stuff electronics techs use to clean dirty circuit boards, switches, potentiometers, and connectors. It removes oxidation and leaves a conductive, protective film. Find it on Amazon. It's worth its high price. Just don't breathe it.

I love that old 9 Lives trademark. Union Carbide made those old carbon-zinc cells. Back in the 1950s, you only needed a jolt of power when the flashbulb had to be lit. A lot of flashguns were 'BC' — battery-capacitor powered. Inserting a bulb would charge a capacitor. Tripping the shutter would discharge the capacitor into the flashbulb, burning the foil inside its oxygen atmosphere. It was rudimentary, but it worked. I still have a couple of old cameras with flash guns that worked like that.

Bought a box lot of old camera equipment at an auction a week or so ago, box, bellows Polaroid ect. Amongst the equipment, I found a Whitehouse Beacon-II 127 camera, circa 1947-1955. . .
Along with the camera a Beacon Flash synchronizer was there. Playing with the flash I found these batteries still in the unit..... VERY very little leakage and the contacts were in great shape !!
I put a meter on the AA's expecting them to be completely drained and found them to still have .7 and .8 V Dead no doubt but I expected them to be at zero. None the less I was amazed that the batteries didn't leak massively and corrode the whole unit.

My parents also complained about my flashbulb issue. It was not the expense because we had a deal about my doing various chores to earn the money. It was my propensity for screwing Press-50 flashlamps into the bathroom fixture so the first family member to brush their teeth in the morning would get a surprise. My goodness- the language they would blurt out! Then they complained about seeing spots before their eyes until lunchtime.

Those big lamps had a fuse built into the base that allowed them to be safely used with 117Volt household line voltage. They were long-peek and had an enormous lumen-second output. Besides my pranks, later on in life, I used those big bulbs to photograph large groups indoors, and outdoors they provide great flash fill at longer distances. I recall shooting a group of 100 choir and orchestra members 35 feet away at f/16 on ASA 400 film. Back in those days, my portable strobes outputted a maximum of 200 watt.second so I would bring back the flashbulbs for certain jobs. Another method was to temporarily replace all the incandescent lightbulbs in large industrial sites with Press 50 or Press -50 flash lamps, set the shutter at "B", open the shutter, flip the light switch, "FLASH/BANG!" close the shutter, and an entire factory was perfectly and (looked) naturally lighted. We had a formula to calculate the aperture settings.

For anyone who is interested, these lamps are still available - here's a link https://flashbulbs.com/

This can save money if anyone was contemplating the purchase of a 4800-watt.second electron flas system!