Distillation is a method of separating chemical substances based
on differences in their volatilities. It usually forms part of a
larger chemical process, and is thus referred to as a unit
operation. Distillation is used for a variety of purposes. Water
is distilled to remove impurities—for example, to remove salt
from seawater. Air is distilled to separate its components, such
as oxygen, which is used for medical applications, and helium,
used for party balloons. The distillation of crude oil produces
fractions useful for specific purposes such as transport, power
generation, and heating. The use of distillation on fermented
solutions to produce distilled beverages with a higher alcohol
content is perhaps the oldest form of distillation, known since
ancient times. Distillation was developed into its modern form
with the invention of the alembic by Islamic alchemist Jabir ibn
Hayyan in around 800 C.E. He is also credited with the invention
of numerous other chemical apparatus and processes that are
still in u