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Your skin wrinkles if you stay in the bathtub a long time because the outermost layer of skin (which consists of dead keratin) swells when it absorbs water. It is tightly attached to the skin below it, so it compensates for the increased area by wrinkling. This happens to the hands and feet because they have the thickest layer of dead keratin cells.
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.
Intradermal injections are somewhat difficult to correctly administer because the skin layers are so thin that it is easy to accidentally punch through to the deeper subcutaneous layer.
Parkinson's disease is both chronic and progressive. This means that it persists over a long period of time and that its symptoms grow worse over time.
The first documented use of surgical anesthesia in the United States was in Connecticut in 1844.