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.
In 1724, a German instrument maker called Gabriel Fahrenheit settled on mercury as the most suitable liquid for measuring temperature. He calibrated his first thermometer using a mixture of ice and water with sea salt as his zero. But salt water has a much lower freezing point than ordinary water, so for his purposes he chose his freezing point as 30, and the temperature inside the mouth of a healthy human as 96.