The Earliest Researches on Liquid Crystals

Here it is proposed a discussion concerning the earliest researches on the liquid crystals. The discussion is based on a book published in 1911, written by Alfred Tutton. In this book, we find described the instrument which was fundamental for observing the mesophases of thermotropic liquid crystals, the “crystallisation microscope”, that Otto Lehmann built for his studies on crystals. It consisted of a polarized-light microscope, equipped by heating and cooling systems for the control of temperature. This experimental set-up allowed Lehmann to study the cholesteryl benzoate, the first material that was discovered by Friedrich Reinitzer as exhibiting a mesophase. In the following years, many other materials were prepared for Lehmann’s studies. In the Tutton’s book, among the chemists who prepared the samples, we can find mentioned Ludwig Gattermann and Daniel Vorländer. We can find also the Vorländer‘s “recipes” to obtain liquid crystalline materials, those which have rod-like molecules