The history of its dissociation is connected with that of the class, viz.
They are yellowish-red solids, which behave as weak bases, their salts undergoing hydrolytic dissociation in aqueous solution.
These colour changes are connected with a dissociation of the molecules.
Sulphuretted hydrogen, H 2 S, a compound first examined by C. Scheele, may be obtained by heating sulphur in a current of hydrogen, combination taking place between 200° C. and 358° C., and being complete at the latter temperature, dissociation taking place above this temperature (M.
The Chemistry of the Sun (1887) is an elaborate treatise on solar spectroscopy based on the hypothesis of elemental dissociation through the intensity of solar heat.