Likely a series-parallel connection of 1.2V conventional cells. Two instances of what you were expecting, connected in parallel. See the handy reference at http://support.apple.com/kb/TA32393?viewlocale=en_US for total capacity of the pack.
The white stuff growing out of the battery seals is mostly potassium hydroxide, which has a way of dissolving human tissue, and can blind you if it gets into your eye. It is very soluble in warm tap water. So if you need to investigate further, put on eye protection and protective rubber gloves and wash gently under the tap as not to splash. Properties similar to drain cleaner lye, just potassium instead of sodium.
After washing the remaining ugly deposits will be mostly relatively insoluble hydroxides and some carbonates that form when the white stuff gets out of its original containment and starts corroding any nearby non-precious metals. Best not to get these irritants in your eyes or lungs. So if you ever try to clean up NiCD or NiMH leak corroded battery holder contacts with a Dremel or similar tool, just remember not to get too close to the dust created and blown about by the tool.
The white stuff growing out of the battery seals is mostly potassium hydroxide, which has a way of dissolving human tissue, and can blind you if it gets into your eye. It is very soluble in warm tap water. So if you need to investigate further, put on eye protection and protective rubber gloves and wash gently under the tap as not to splash. Properties similar to drain cleaner lye, just potassium instead of sodium.
After washing the remaining ugly deposits will be mostly relatively insoluble hydroxides and some carbonates that form when the white stuff gets out of its original containment and starts corroding any nearby non-precious metals. Best not to get these irritants in your eyes or lungs. So if you ever try to clean up NiCD or NiMH leak corroded battery holder contacts with a Dremel or similar tool, just remember not to get too close to the dust created and blown about by the tool.