In my kitchen cupboard I have olives in brine and pickled onions in vinegar. There is no doubt that when I go to remove an olive or onion with my fingers (I know I should use a fork) the vinegar feels warmer than the brine. I even filled a jar with water and left it overnight in the cupboard to check. It felt colder than the vinegar. And friends have verified my finding. Surely the vinegar should be at cupboard temperature? Has anybody any idea what's going on?

When I open a new jar of marmalade the contents are a nice, semi-solid, homogenous mass with a smooth surface, however old the jar is. Yet when I make a spoonful-sized hole in the flat surface to remove some marmalade, the next time I open the jar a couple of days later, the hole has started to fill with a syrupy liquid. What is it about breaking the surface of the marmalade that sets this process in motion? It continues until the jar is empty.