Birthday trains

Today we had T's 5th birthday party for his school friends at the Malden and District Society of Model Engineers' railway in Thames Ditton. A good time had by all with lots of train rides, cake and ice cream.

Last year I didn't apply my knowledge of colligative properties and failed to keep ice lollies from melting by just having them in an ice box with ice. This year I added a good quantity of table salt and a little water to the ice and then packed the ice lolly boxes in plastic bags within the salty ice/water mix. The initial packing was a bit tricky as the water on the surface of the ice rapidly froze as the temperature dropped, and welded the cubes together. When first set up (about 12 noon) my thermometer showed below -10 degC (the lowest point on its scale). By 5pm the lollies were just beginning to get soft, which I think is pretty good on a day where the air temperature was about 25 degC.

M and I between us also came up with a good method for labelling water bottles in a communal ice-water tub: plastic plant labels (the sort you tie through itself) tucked through the outer label and a lumocolor permanent marker.