History
The phenomenon was first noticed over one hundred years ago (in 1896) by the German chemist Raphael E. Liesegang, and has aroused the curiosity of chemists for many years. It was first noted when he dropped a solution of silver nitrate on to a thin layer of gel containing potassium dichromate. After a few hours, sharp concentric rings of insoluble silver dichromate formed. When formed in a test tube by diffusing one component from the top, layers or bands of precipitate form, rather than rings.
Read more about this topic: Liesegang Rings
Famous quotes containing the word history:
“What has history to do with me? Mine is the first and only world! I want to report how I find the world. What others have told me about the world is a very small and incidental part of my experience. I have to judge the world, to measure things.”
—Ludwig Wittgenstein (1889–1951)
“Properly speaking, history is nothing but the crimes and misfortunes of the human race.”
—Pierre Bayle (1647–1706)
“Perhaps universal history is the history of the diverse intonation of some metaphors.”
—Jorge Luis Borges (1899–1986)