[1] Denigés' reagent is used to detect isolefin or tertiary alcohols which can be easily dehydrated to form isoolefin in the presence of acid.
Treatment of solutions containing either isolefin or tertiary alcohols with this reagent will result in the formation of a solid yellow or red precipitate.
Inhalation of the Denigés' reagent can result in acute poisoning: causing tightness in the chest, difficulties breathing, coughing and pain.
Lastly, ingestion of mercury sulfate will cause necrosis, pain, vomiting, and severe purging.
Ingestion can result in death within a few hours due to peripheral vascular collapse.