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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).
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
Oliver Wendell Holmes is credited with introducing the words "anesthesia" and "anesthetic" into the English language in 1846.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.
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