Today is the birthday of Thomas Charles Hope, a Scottish chemist born in 1766. Although he considered himself a teacher, Hope is remembered for two original contributions to chemistry. Hope calibrated a phenomenon--the strange expansion and contraction of water as it changes temperature--that had been anecdotally observed since the 17th century, but which drew skepticism even from top chemists such as Robert Hooke and John Dalton. In experiments published in 1805, Hope measured the temperature of water's maximum density at 39.1 degrees Fahrenheit; the accepted modern value is 39.2 degrees Fahrenheit. Hope is also credited with being the first to identify the element strontium.
[Source: Trevor I. Williams, Ed., A Biographical Dictionary of Scientists (John Wiley & Sons, 3rd ed., New York, 1982).]