The Fischer assay is a standardized laboratory test for determining the oil yield from oil shale

Oil shale

Oil shale, an organic-rich fine-grained sedimentary rock, contains significant amounts of kerogen from which liquid hydrocarbons called shale oil can be produced...

 to be expected from a conventional shale oil extraction. A 100 gram oil shale sample crushed to <2.38 mm is heated in a small aluminum retort

Retort

In a chemistry laboratory, a retort is a glassware device used for distillation or dry distillation of substances. It consists of a spherical vessel with a long downward-pointing neck. The liquid to be distilled is placed in the vessel and heated...

 to 500 °C (932 °F) at a rate of 12°C/min (22°F/min), and held at that temperature for 40 minutes. The distilled vapors of oil, gas, and water are passed through a condenser

Condenser (heat transfer)

In systems involving heat transfer, a condenser is a device or unit used to condense a substance from its gaseous to its liquid state, typically by cooling it. In so doing, the latent heat is given up by the substance, and will transfer to the condenser coolant...

 and cooled with ice water into a graduated centrifuge tube. The oil yields achieved by other technologies are often reported as a percentage of the Fischer Assay oil yield.

The original Fischer Assay test was developed in the early low temperature coal retorting research by Franz Joseph Emil Fischer

Franz Joseph Emil Fischer

Franz Joseph Emil Fischer was a German chemist. He and Hans Tropsch discovered the Fischer-Tropsch process. With Hans Schrader he developed the Fischer Assay, a standardized laboratory test for determining the oil yield from oil shale to be expected from a conventional shale oil extraction...

and Hans Schrader. It was adapted for evaluating oil shale yields in 1949 by K. E. Stanfield and I. C. Frost.