This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
In any fever where the nervous system is specially depressed, phosphoric acid is indicated; it assuages thirst, and helps to remove exhaustion; its pleasant taste is one advantage over the other mineral acids.
Stromeyer, and others, recommend it in "eruptive fevers." The following is a convenient form: - R. Acidi phosphorici diluti, fl. 3 iij.; gly-cerini, fl. 3 j.; decocti hordei, Oij.: mix, and use when cold as a common drink.