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 caries, M. Leutin applied dilute phosphoric acid to the affected bone with the idea of supplying a deficient element, and practically this sometimes relieves and improves the bone-condition. Its good effect is, however, better seen from internal administration, especially if much hectic be present. It is said to be also beneficial in cases of unusual depositions of phosphate of lime, as in exostosis, and bony tumors generally (Neligan, Garrod). Wormald states that the detection of phosphoric acid in pus is diagnostic of necrosis (Lancet, ii., 1862, p. 440).