What is antifreeze

An antifreeze is a liquid that is added to water to keep it from freezing. When water freezes and turns to ice, it expands—takes up more space. The force of water expanding is so great that it will break the hardest metal. Water is used in automobile engines to keep them cool while they run, and if this water is allowed to freeze in the winter it can crack the iron block of the engine. That is why antifreezes are necessary. Water freezes at 32 degrees (on a Fahrenheit thermometer) and in most places it becomes much colder than that in the winter.

Suppose the cooling system of an automobile holds nine quarts of water. You take out four quarts of water and put in four quarts of an antifreeze that will not freeze until the temperature drops to 40 degrees below zero. This mixture will not freeze until the temperature drops to zero. By putting in five quarts of the antifreeze, you can keep the mixture from freezing until the temperature drops to 8 degrees below zero. The amount of antifreeze you put in will depend on how cold it is likely to be. Alcohol is a good antifreeze, but when the automobile is running it becomes hot and the alcohol boils away, so it must be replaced very often.

 Most people use antifreezes that do not boil away when the engine is running. There are several chemicals that do this. One of the most popular is called ethylene glycol, though you will seldom hear it called that, because it is sold under various "trade names." An instrument called the hydrometer, about which there is a separate article, is used in filling stations to test the liquid in the cooling system and find out the temperature at which it will freeze.