Carsten Olsen was employed at Carlsberg Laboratory and worked as an assistant to the Danish chemist who introduced the concept of pH in 1843.
Carsten Erik Olsen (March 1, 1891  August 19, 1974) was a Danish plant ecologist and plant physiologist, who pioneered the study of plant nutrition in soils of different pH. 
 He was then employed by the Carlsberg Laboratory as an assistant to the chemist S. P. L. Srensen, later in his own lab. 
Sren Peder Lauritz Srensen (9 January 1868  12 February 1939) was a Danish chemist, famous for the introduction of the concept of pH, a scale for measuring acidity and alkalinity. 
