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 is about 7.5 minutes. The longest total solar eclipse from 4000 BCE to 8000 CE, a span of 12,000 years, will occur on July 16, 2186 and will last 7 minutes 29 seconds. Its path sweeps across Colombia, Venezuela and Guyana. The August 21, 2017 total solar eclipse, by comparison, will last a maximum of 2 minutes 43 seconds.