Rheumatism, Saltpetre Good in Cases of

"One ounce of saltpetre to one pint of water. Take one teaspoonful of the above in a large glass of water, about six times daily." The saltpetre acts on the kidneys, carrying off the impurities in this way. Care should be taken not to continue this treatment too long at a time, as continued use would result in injury to the kidneys.

Source: Mother's Remedies: Over One Thousand Tried and Tested Remidies from Mothers of the United States and Canada, T. J. Ritter