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:
“the future is simply nothing at all. Nothing has happened to the present by becoming past except that fresh slices of existence have been added to the total history of the world. The past is thus as real as the present.”
—Charlie Dunbar Broad (1887–1971)
“The history of the Victorian Age will never be written: we know too much about it.”
—Lytton Strachey (1880–1932)
“I am ashamed to see what a shallow village tale our so-called History is. How many times must we say Rome, and Paris, and Constantinople! What does Rome know of rat and lizard? What are Olympiads and Consulates to these neighboring systems of being? Nay, what food or experience or succor have they for the Esquimaux seal-hunter, or the Kanaka in his canoe, for the fisherman, the stevedore, the porter?”
—Ralph Waldo Emerson (1803–1882)