Dear Mr AWK;
Of course!, ─ That’s very true!
But at the same time the “correct” Ferrichloride-Test empowers you to distinguish between Ethanoic Acid and Pro-pionic Acid, or more correct between Acetic Acid and “Pionic Acids”.
Apropos:
In case of nearly pure Samples there is a much easer Test: “Put two Test Tubes” for 2 - 3 hours into the normal Fridge and watch the result.
Good Luck!
ARGOS++