To make the Ice.
Get a few pounds of ice, break it almost to powder, throw a large handful and a half of salt among it. You must prepare it in a part of the house where as little of the warm air comes as you can possibly contrive. The ice and salt being in a bucket, put your cream into an ice pot, and cover it; immerse it in the ice, and draw that round the pot, so as to touch every possible part. In a few minutes put a spatula or spoon in, and stir it well, removing the parts that ice round the edges to the centre. If the icecream or water be in a form, shut the bottom close, and move the whole in the ice, as you cannot use a spoon to that without danger of waste.
Note. When any fluid tends towards cold, the moving it quickly accelerates the cold; and likewise, when any fluid is tending to heat, stirring it will facilitate its boiling.