births
January 9, 1868
S. P. L. Sørensen, Danish chemist and academic (died 1939)
S. P. L. Sørensen
Søren Peter Lauritz Sørensen was a Danish chemist, known for the introduction of the concept of pH, a scale for measuring acidity and alkalinity.
January 9
January 9 is the ninth day of the year in the Gregorian calendar; 356 days remain until the end of the year.