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When Gabriel Fahrenheit invented the first mercury thermometer, he called "zero degrees" the lowest temperature he was able to attain with a mixture of ice and salt. For the upper point of his scale, he used 96°, which he measured as normal human body temperature (we know it to be 98.6° today because of more accurate thermometers).
A good example of polar molecules can be understood when trying to make a cake. If water and oil are required, they will not mix together. If you put them into a measuring cup, the oil will rise to the top while the water remains on the bottom.
In most climates, 8 to 10 glasses of water per day is recommended for adults. The best indicator for adequate fluid intake is frequent, clear urination.
Nitroglycerin is used to alleviate various heart-related conditions, and it is also the chief component of dynamite (but mixed in a solid clay base to stabilize it).
The word drug comes from the Dutch word droog (meaning "dry"). For centuries, most drugs came from dried plants, hence the name.