The Kipp Generator was invented in 1844 by Petrus Jacobus Kipp
and used throughout the rest of the 19th and the entire 20th centuries.
Indeed, Kipp generators are still being used in some places.
The most commonly known use is for preparation of hydrogen sulfide
in qualitative inorganic analysis by reaction of sulfuric acid
with ferrous sulfide FeS, carbon dioxide by reaction of hydrochloric
acid with calcium carbonate, and hydrogen by reaction of an acid
with a suitable metal.
The apparatus is made of three vertically stacked cylinders, roughly
resembling a snowman. The solid material (eg. iron sulfide) is
placed into the middle cylinder, the acid is put into the top
cylinder. A tube extends from the top cylinder into the bottom
cylinder. The middle cylinder has a tube with a stopcock attached,
which is used to draw off the evolved gas. When the stopcock is
closed, the pressure of the gas in the middle cylinder rises and
expels the acid back into the top cylinder, until it is not in
contact with the solid material anymore, and the chemical reaction