It is now obvious that if we have filled two pails, the one with "the sweet lemonade," and the other with the ice and salt, very soon our lemonade will be a solid block of ice.

To prevent this it must be constantly stirred, and, as the lemonade would of course freeze first against the sides of the pail, these sides must be constantly scraped.

Inside the inner pail, consequently, there is a stirrer, which, by means of a handle, continually scrapes the side of the pail.

It is obvious that if the stirrer is fixed, and the pail itself made to revolve, that is the same as if the pail were fixed and the stirrer made to revolve.

To make lemon-water ice, therefore, place the lemonade in the inner pail, surrounded with chopped ice and salt, two parts of the former to one of the latter, turn the handle, and in a few minutes the ice is made.