S. P. L. Sørensen

Who was S. P. L. Sørensen?

Søren

Peder Lauritz Sørensen (January 9, 1868 - February 12, 1939). Born in

Havrebjerg, Denmark, Sørensen was a Danish chemist, famous for the

introduction of the concept of pH, a scale for measuring acidity. From

1901 to 1938 he was head of the prestigious Carlsberg Laboratory,

Copenhagen. While working at the Carlsberg Laboratory he studied the

effect of ion concentration on proteins, and because the concentration

of hydrogen ions was particularly important, he introduced the pH-scale

as a simple way of expressing it in 1909. The article in which he

introduced the scale (using the notation p H), described two new

methods for measuring acidity. The first method was based on

electrodes, while the second involved comparing the colors of samples

and a preselected set of indicators. He is also known for the Sørensen

formol titration.