Carl Zeiss Jena Refractometer a) Manufacturer Carl Zeiss Jena, Germany I.Carl Zeiss Jena Series #: 59849, produced in the 1930s. Note: Original thermometer is present. Ernst Abbé designed the refractometer in 1869 and it was commercially available from Carl Zeiss in 1881. The Zeiss factory in Jena produced refractometers until it was destroyed by the Allies during World War II in 1945. The Abbe refractometer has temperature-controlled prisms that use water circulating through the prism holder/heating block. The Abbe refractometer works as an easy way to determine the refractive index and was therefore often used to determine the purity of liquids. Often used in the fat/sugar industry and in clinical trials. Photos are part of the description. Will be carefully packed for shipping. The shipping costs to an island, also within Europe, can be found in the category "other destinations".