M 1737 (OTTO) Mercuric thiocyanate, GR 99%+ Cas 592-85-8 - used in the determination of chloride ions in water by UV-visible spectroscopy. M 1737 (OTTO) Mercuric thiocyanate, GR 99%+ Cas 592-85-8 - used as a precursor to potassium tris(thiocyanato)mercurate(II) and cesium tris(thiocyanato)mercurate(II).