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Pubic lice (crabs) are usually spread through sexual contact. You cannot catch them by using a public toilet.
Hippocrates noted that blood separates into four differently colored liquids when removed from the body and examined: a pure red liquid mixed with white liquid material with a yellow-colored froth at the top and a black substance that settles underneath; he named these the four humors (for blood, phlegm, yellow bile, and black bile).
The ratio of hydrogen atoms to oxygen in water (H2O) is 2:1.
Signs of depression include feeling sad most of the time for 2 weeks or longer; loss of interest in things normally enjoyed; lack of energy; sleep and appetite disturbances; weight changes; feelings of hopelessness, helplessness, or worthlessness; an inability to make decisions; and thoughts of death and suicide.
In 1864, the first barbiturate (barbituric acid) was synthesized.