Klett colorimeter by Bausch and Lomb Optical Company, American. Used in Sir Hans Krebs laboratory, Sheffield, c.1930-1940
A ‘Klett’ colorimeter compares colours of samples with standard colours during chemical analysis. This gives readings on the Klett scale. These readings indicate the concentration or density of the sample. Colorimeters can be used to assess the quantity of plasma protein in a blood sample or the components within urine. The instrument is used like a microscope. The sample is viewed by looking down the two adjustable lenses. The colour number is read off a sliding scale.
This Klett colorimeter was made by the Bausch and Long Optical Company. It was used in the laboratory of pioneering biochemist Hans Krebs (1900-81) in Sheffield, England during the 1930s and 1940s. Krebs was famous for his description of the ‘citric acid cycle’. This is the series of reactions where cells produce energy. Krebs was awarded the Nobel Prize in Physiology or Medicine 1953 for his discovery.