Marquis Reagent -
Concentrated Sulfuric Acid (H2S04)
and
Formaldehyde (or Methanol which is in equilibrium with Formaldehyde under strongly acidic conditions)
There is no hydrochloric acid in the Marquis Reagent.
If you want to make yer own Marquis Reagent
cited from
"Spot Test Analysis, Clinical, Enviromental, Forensic, and Geochemical Applications"
Jungreis
(1997)
"Mix 10mL concentrated sulfuric acid with 8-10 drops 40%formaldehyde solution."
I will be summarizing the drug section of this book a little later and posting it here - keep an eye out!
Mateo