Can we make Ice Colder?

On Friday we posed the question can we make ice colder? We talked about ice and how water can change and measured the temperature of the ice in the cup with a thermometer. Ice freezes at 0 c. Most of our ice was round about freezing point. The ice was starting to melt as it was absorbing the heat within the room.

We added salt and stirred the ice and we saw the thermometer level move quite quickly down  to -15c and then to -20 c. The ice cubes started to stick together.
What caused this to happen?

We know that salt causes ice to melt more quickly and it becomes slushy and colder. Rapidly melting ice absorbs heat more quickly and it becomes colder.