Nessler cylinders (also named color comparison cylinders or color comparing cylinders) are laboratory tubes with a fixed

volume Volume is a measure of regions in three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch) ...

, made of

glass Glass is an amorphous (non-crystalline solid, non-crystalline) solid. Because it is often transparency and translucency, transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window pane ...

with optically plane bottom. On the walls, there are marks of the nominal stroke volume (usually 100 ml) and possibly one halfway mark (usually 50 ml). Nessler cylinders are used for

colorimetric analysis Colorimetric analysis is a method of determining the concentration of a chemical element or chemical compound in a solution with the aid of a color reagent. It is applicable to both organic compounds and inorganic compounds and may be used with or ...

, such as

APHA color APHA color, also referred to as the Hazen scale, and more appropriately as the Pt/Co scale, Platinum Cobalt(Pt/Co) scale, is a color standard named for the American Public Health Association and defined by ASTM D1209. It was originally intended to ...

. The color of the substance contained in a Nessler cylinder is visually compared with the model. The tubes often carry out a series of calibrations of solutions of increasing concentrations, which functions as a comparative scale. To minimize differences in the subjective impression of the color of the solution of the substance to be analyzed, cylinders of a series should have the same characteristics - height, diameter, and thickness of glass. Basically, there are four types of used cylinders: * high with a capacity of 50 ml (about 300 mm in height, approximately 21 mm in diameter) * low with a capacity of 50 ml (about 175 mm in height, approximately 25 mm in diameter) * high with a capacity of 100 ml (about 375 mm in height, approximately 24 mm in diameter) * low capacity of 100 ml (about 210 mm in height, approximately 34 mm in diameter) However, these parameters (except volume) can vary significantly between two cylinders. Hehner cylinders differ in that they are scaled to full height. Due to the spread of automated

spectrophotometers Spectrophotometry is a branch of electromagnetic spectroscopy concerned with the quantitative measurement of the reflection or transmission properties of a material as a function of wavelength. Spectrophotometry uses photometers, known as sp ...

, colorimetric assay methods using Nessler cylinders and visual assessment are used very rarely. However, Nessler cylinders are still used as reaction vessels, in the same way as

test tubes A test tube, also known as a culture tube or sample tube, is a common piece of laboratory glassware consisting of a finger-like length of glass or clear plastic tubing, open at the top and closed at the bottom. Test tubes are usually placed in ...

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External links

*Witold Hermanowicz, Vera Dożańska, John Dojlido, Bohdan Koziorowski: Physico-chemical examination of water and wastewater. Warsaw: Arkady, 1976, pp 19–21. UKD 628.31:628.1.03:543.3. Laboratory glassware