Difficult choices as death nears. As the changes described in this article develop in the final days or hours of a progressive terminal illness, difficult choices may arise. There may be questions about whether to provide food and fluids, receive blood transfusions, or treat infections.
The use of mercury in thermometers dates back hundreds of years. It was widely used because it reliably expands and contracts with changes in temperatures. It is highly poisonous, however, and can enter the body through the respiratory or digestive tracts, or directly through the skin.
Because mercury is the only liquid metal and liquids expand more than solids on heating. Mercury is one of the few elemental substances that is liquid at room temperature. Like all substances, mercury linearly expands as temperature increases. Coupling these two properties, a thermometer is formed.