Template:Are You Sure/January 18

Diethylzinc molecule, Zn(C2H5)2 -- structural model (above). ball-and-stick model (below). Edward Frankland first reported the compound in 1848 from zinc and ethyl iodide; it was the first organozinc compound discovered.

• ... that physicist, mathematician, astronomer, and musician Jean-Pierre Christin proposed (1743) the reversal of the Celsius thermometer scale (from water boiling at 0 degrees and ice melting at 100 degrees, to where zero represented the freezing point of water and 100 represented the boiling point of water), and that his system was widely accepted and is still in use today?

• ... that chemist and physicist Henri Victor Regnault discovered that not all gases expand equally when heated, and that Boyle's Law is only an approximation, especially at temperatures near a substance's boiling point?
• ... that mathematician, engineer, and politician Charles Dupin is particularly known for his work in mathematics, where the Dupin cyclide and Dupin indicatrix are named after him; and for his work in the field of statistical and thematic mapping (he created the earliest known choropleth map)?