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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).
Only one in 10 cancer deaths is caused by the primary tumor. The vast majority of cancer mortality is caused by cells breaking away from the main tumor and metastasizing to other parts of the body, such as the brain, bones, or liver.
Aspirin is the most widely used drug in the world. It has even been recognized as such by the Guinness Book of World Records.
Thyroid conditions cause a higher risk of fibromyalgia and chronic fatigue syndrome.
In 1885, the Lloyd Manufacturing Company of Albany, New York, promoted and sold "Cocaine Toothache Drops" at 15 cents per bottle! In 1914, the Harrison Narcotic Act brought the sale and distribution of this drug under federal control.
![Cardiac catheterization. Insertion of a tube called a catheter through a blood vessel. In this examp](https://biology-forums.com/gallery/47/medium_14755_11_11_12_7_14_27_100261340.jpeg)
![Electrocardiography. (a) Electrodes are placed on the patient’s chest to record the electrical event](https://biology-forums.com/gallery/47/medium_14755_11_11_12_7_15_46_100311063.jpeg)