Inscribed: "1er cercle chromatique de Mr. Chevreul renfermant les couleurs franches."

Chevreul’s first chromatic circle shows 72 colors in their purest hues.

Inscribed: "3ème cercle chromatique de Mr. Chevreul renfermant les couleurs rabattues, à 2/10 de noir."

Chevreul’s third chromatic circle shows the 72 pure hues from Plate V subdued with 2/10 black.

Inscribed: "Zône circulaire dont les couleurs sont continues. On la suppose formée d’une reunion de zônes excessivement étroites et contigues parmi lesquelles il en est trois qui sont a des distances égales, RR, JJ, et…

The gamut of purple-red tones from light to dark along a 20-tone scale, where positions 0 and 21 correspond to white and black respectively.

The gamut of purple tones from light to dark along a 20-tone scale, where positions 0 and 21 correspond to white and black respectively.

The gamut of blue-purple tones from light to dark along a 20-tone scale, where positions 0 and 21 correspond to white and black respectively.

The gamut of blue tones from light to dark along a 20-tone scale, where positions 0 and 21 correspond to white and black respectively.

The gamut of green tones from light to dark along a 20-tone scale, where positions 0 and 21 correspond to white and black respectively.

The gamut of yellow-green tones from light to dark along a 20-tone scale, where positions 0 and 21 correspond to white and black respectively.

The gamut of green-blue tones from light to dark along a 20-tone scale, where positions 0 and 21 correspond to white and black respectively.

The gamut of yellow tones from light to dark along a 20-tone scale, where positions 0 and 21 correspond to white and black respectively.

The gamut of red tones from light to dark along a 20-tone scale, where positions 0 and 21 correspond to white and black respectively.

The gamut of red-orange tones from light to dark along a 20-tone scale, where positions 0 and 21 correspond to white and black respectively.

The gamut of orange tones from light to dark along a 20-tone scale, where positions 0 and 21 correspond to white and black respectively.

The gamut of orange-yellow tones from light to dark along a 20-tone scale, where positions 0 and 21 correspond to white and black respectively.

The gamut of grey tones from light to dark along a 20-tone scale, where positions 0 and 21 correspond to white and black respectively.

This piece is the cover to Bulletin 7389 for the Model 160 wavelength selectable detector used in liquid chromatography.

This is a double-beam instrument that measures fluorescence through spectroscopy.

Printed portrait of French scientist and professor Jules Francois Joubert (1834-1910), who assisted French chemist, biologist and microbiologist Louis Pasteur (1822-1895). Joubert collaborated with Pasteur in 1877,…

This liquid chromatography recording detector system consists of a dual-beam spectrophotometer, a pH meter, and a conductivity cell.

Colorimeters are used to quantify the concentration of a solute in a solution by measuring the absorbance of a particular wavelength or color of light by the solution.

This is a double-beam instrument that measures fluorescence through spectroscopy.

This liquid chromatography recording detector system consists of a dual-beam spectrophotometer, a pH meter, and a conductivity cell.

This chromatography instrument was first manufactured in the mid-1960s. It allowed operators to run several analyses at once and print out results, instead of compiling them separately. Components included pH and…

General view of a colorimeter used to analyze nitrogen dioxide at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. With regards to chemistry, colorimeters are used to…