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 scientist trained in the study of chemistry. Chemists study the composition of matter and its properties. Chemists carefully describe ...

. 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 ...

measure of

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogeno ...

concentration.

Biography

Neßler studied at the

University of Freiburg The University of Freiburg (colloquially german: Uni Freiburg), officially the Albert Ludwig University of Freiburg (german: Albert-Ludwigs-Universität Freiburg), is a public research university located in Freiburg im Breisgau, Baden-Württe ...

from 1853 to 1856, when he attained his PhD. After his Ph.D. Neßler worked for some months with

Lambert Heinrich von Babo Lambert Heinrich Joseph Anton Konrad Freiherr von Babo (November 25, 1818 – April 15, 1899) was a German chemist. Life Babo was the son of the agronomist Lambert Joseph von Babo and his first wife Karoline Ehrmann. The oenologist August Wilhel ...

and

Robert Wilhelm Bunsen Robert Wilhelm Eberhard Bunsen (; 30 March 1811 – 16 August 1899) was a German chemist. He investigated emission spectra of heated elements, and discovered caesium (in 1860) and rubidium (in 1861) with the physicist Gustav Kirchhoff. The Bun ...

and then joined a chemical company in Karlsruhe.

Nessler cylinder

A Nessler cylinderhttp://www.cardinal.com/us/en/distributedproducts/ASP/T4500-61.asp?cat=laboratory 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 or quantitative procedure designed to identify, quantify, or characterise a chemical compound or chemical group. Purposes Chemical testing might have a variety of purposes, such as to: * Determine ...

. 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–Lambert law, also known as Beer's law, the Lambert–Beer law, or the Beer–Lambert–Bouguer law relates the attenuation of light to the properties of the material through which the light is travelling. The law is commonly applied t ...

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