acidulate with sulphuric acid to fix any ammonia present.
"Aids to Forensic Medicine and Toxicology"
W. G. Aitchison Robertson
As for the drinks, they must be cold, consisting of water with sufficient flour mixed in it to whiten it, and a little vinegar or sulphuric acid, to acidulate it.
"On the cattle plague: or, Contagious typhus in horned cattle. Its history, origin, description, and treatment"
Honoré Bourguignon
In such Cases we found nothing to answer so well as to give freely of the Bark; to acidulate their Drinks with the spiritus vitrioli; to allow them as much Red Wine as the Strength and present Circumstances could bear; and at the same Time to support the Patient’s Strength by a mild Diet, of light Digestion; as Water or Rice Gruel, Panado, weak Broth, and the like.
"An Account of the Diseases which were most frequent in the British military hospitals in Germany"
Donald Monro