Designed by Léon Laurent, this saccharimeter was presented to the Academy of Sciences in 1882 by Alfred Cornu. The device consists of a lens, followed by a nicol prism that converges light on the opening of a diaphragm and a quartz crystal. The latter is used as a compensator. It considerably improves the conditions for observing and measuring the concentration of granulated sugar dissolved in aqueous solutions, in particular, the urine of diabetics, by eliminating the need to burn sodium.
 Set of two prisms from the size of the same spath crystal following a diagonal plane used to study the polarization of light.