The same principal is put to use to speed cooking in the pressure cooker This appliance reduces cooking times by trapping the steam that escapes from boiling water, thereby increasing the pressure on the liquid, and so raising its boiling point — and maximum temperature — to about 250ºF/120ºC This is the equivalent of boiling water in an open pan at the bottom of a pit 19,000 feet/5,800 meters below sea level The pressure cooker was invented by the French physician Denis Papin in the 17th century The Boiling Point Is Increased by Dissolved Sugar and Salt When salt, sugar, or any other water-soluble substance is added to pure water, the boiling point of the resulting solution becomes higher than the boiling point of water, and the freezing point lower than water’s freezing point Both effects are due to the fact that the water molecules are diluted by the dissolved particles, which interfere with the water molecules as they change phase from liquid to gas or liquid to solid In the case of the boiling point, the solution contains sugar molecules or salt ions that also absorb heat energy, but cannot themselves turn into a gas So at water’s normal boiling point, there is a smaller proportion of molecules with enough energy to escape from the liquid and form a bubble of vapor, and the cook has to add more energy than usual in order to get those bubbles to form The boiling point and freezing point rise and fall predictably as the concentration of dissolved sugar or salt increases, a fact that is handy for making both sugar candies and ice creams It’s true that adding salt to water raises its boiling point, and so speeds cooking However, it takes one ounce of salt in a quart of water — around the salinity of the ocean — to raise the boiling point a negligible 1ºF A Denverite who wanted to boil water at the ...by the dissolved particles, which interfere with the water molecules as they change phase from liquid to gas or liquid to solid In the case of the boiling point, the solution contains sugar... liquid and form a bubble of vapor, and the cook has to add more energy than usual in order to get those bubbles to form The boiling point and freezing point rise and fall predictably as the concentration... However, it takes one ounce of salt in a quart of water — around the salinity of the ocean — to raise the boiling point a negligible 1ºF A Denverite who wanted to boil water at the