from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Of or pertaining to polythionic acid or its derivatives
from The Century Dictionary and Cyclopedia
- Noting any one of a series of acids each member of which contains in its molecule two atoms of hydrogen and six of oxygen, with a number of sulphur atoms varying from two to six: as dithionic acid, H2S2O6, and tetrathionic acid, H2S4O6.
Sorry, no etymologies found.
The explanation was that the oxidation of sulphite to sulphuric acid does not proceed directly, but by the precipitation of elementary sulphur, which would indicate that this reaction does not proceed monomolecularly, but probably by way of a polythionic acid.