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 {| This man is filling the cans with distilled water. It is in these cans the ice is made. On the bottom of the tube you see held in its place in the can with braces is a valve, opening upward. When this valve is pressed against the bottom of the can it lets out enough water to fill the can almost to the top. When the water reaches a certain height it is stopped by a floating check valve. A floating check valve is one which has a hollow metal ball attached so that when the water in which it floats reaches a certain height it turns the valve and either shuts off the water or releases it, as desired.
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Most artificial ice is made by what is called the compressor system. It is called the compressor system because the ammonia with which che freezing is done is first compressed by means of powerful steam pumps. These pumps then force it through pipes over which cold water is running. This cold water bath still further condenses the gas to a liquid state, which drives out all the heat there is in it. The illustration shows how water is kept playing on the pipes containing the compressed ammonia.

After the ammonia has been condensed to a liquid state. It passes into a great cylinder called an evaporator. Here it begins to expand again back to a gas and passes into parallel pipes like those you have just seen. But these pipes run through a tank filled with brine. When the ammonia is condensed to a liquid form it gives up all its heat, just as water does when it turns to ice. Then, when it is allowed to expand in passing through the pipes in the brine tank, it absorbs the heat from the brine and makes it freezing cold In this brine tank are set the cans of distilled water to be frozen. This illustration shows the cans being lowered into the brine.