A substance is anhydrous if it contains no water, for example, salts lacking their water of crystallisation. The way of achieving the anhydrous form differs from one substance to another.
A partial solar eclipse at its peak at 3:37 p.m. in Mesa on Oct. 23, 2014. The eclipse was visible over most of North America and covered 44 percent of the Arizona sun. Michael Chow/The Republic.
Past Eclipses. The last time a total solar eclipse spanned the contiguous United States was in 1918. The path of totality entered the U.S. through the southwest corner of Washington state and passed over Denver, Jackson (Mississippi) and Orlando before exiting the country at the Atlantic coast of Florida. Prior to 2017, the most recent total solar eclipse in the Lower 48 was in 1979.