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.
This will be the last total solar eclipse in the United States until April 8, 2024. It's not quite as long of a wait as you might have thought, but it won't stretch the width of the country. Instead, it will move from Mexico to Maine and then traverse New Brunswick and Newfoundland.