Julius Neßler (6 June 1827 – 19 March 1905) was a German

chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a graduated scientist trained in the study of chemistry, or an officially enrolled student in the field. Chemists study the composition of ...

. He devised the chemical solution '' Nessler's reagent'' which provides a

colorimetric Colorimetry is "the science and technology used to quantify and describe physically the human color perception". It is similar to spectrophotometry, but is distinguished by its interest in reducing spectra to the physical correlates of color p ...

measure of

ammonia Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...

concentration.

Biography

Neßler was born in 1827. He studied at the

University of Freiburg The University of Freiburg (colloquially ), officially the Albert Ludwig University of Freiburg (), is a public university, public research university located in Freiburg im Breisgau, Baden-Württemberg, Germany. The university was founded in 1 ...

from 1853 to 1856, when he attained his PhD. After his Ph.D. Neßler worked for some months with Lambert Heinrich von Babo and Robert Wilhelm Bunsen and then joined a chemical company in Karlsruhe. He died on 19 March 1905.

Nessler cylinder

A Nessler cylinder is a simple type of colorimeter. It is best known for use with Nessler's reagent but can be used for any colorimetric

chemical test In chemistry, a chemical test is a qualitative property, qualitative or Quantitative property, quantitative procedure designed to identify, quantify, or characterise a chemical compound or substituent, chemical group. Purposes Chemical testing m ...

. In practice, a pair of tubes is used, set on a white background. One tube is filled with color reagent and a known quantity of sample to act as a reference. The sample to be tested is mixed with color reagent in a beaker and the color is allowed to develop. The mixture is then poured, a little at a time, into the second tube until the intensity of color in the two tubes is identical. The heights of the liquid columns in the two tubes are measured and the concentration of the sample solution can be calculated using the

Beer–Lambert law The Beer–Bouguer–Lambert (BBL) extinction law is an empirical relationship describing the attenuation in intensity of a radiation beam passing through a macroscopically homogenous medium with which it interacts. Formally, it states that the ...

References

1827 births 1905 deaths 19th-century German chemists People from the Grand Duchy of Baden University of Freiburg alumni People from Kehl {{Germany-chemist-stub