A potassium dichromate voltaic pile, invented by the German Johann Christian Poggendorff (1796-1877) in 1842, it bears the name of Grenet who in 1856 gave it its final configuration, making it more practical and manageable.
It consists of a glass recipient that has the form of a round bottle with a long wide neck. It is filled to half its capacity with a liquid which, according to Poggendorff, should be composed of 17 parts potassium dichromate dissolved in 100 parts of distilled water with the addition of 22 parts sulphuric acid. But according to Grenet, the percentages by weight should be respectively: 10, 100 and 30, but many other compositions have been suggested and used.
The exemplar presented here has a height of 27.5 cm. The top of the neck has a wide band of metal on which an hard rubber lid fits tightly by pressure....continues