Melzer's reagent

Depending on the formulation, it consists of approximately 2.50-3.75% potassium iodide and 0.75–1.25% iodine, with the remainder of the solution being 50% water and 50% chloral hydrate.

[4] Due to the legal status of chloral hydrate, Melzer's reagent is difficult to obtain in the United States.

[4] In response to difficulties obtaining chloral hydrate, scientists at Rutgers formulated Visikol[5] (compatible with Lugol's iodine) as a replacement.

In 2019, research showed that Visikol behaves differently to Melzer’s reagent in several key situations, noting it should not be recommended as a viable substitute.

The chloral hydrate is a clearing agent, bleaching and improving the transparency of various dark-colored microscopic materials.