℞ The most pure Nitre lbj. Spirit of Nitre rectified lbj ss. mix, and digest them together for some hours; then put it upon the Fire, and evaporate to driness; so will you have at bottom, a very white Salt, break the Glass, and take it forth.
This may supply the place of Sal Prunellae, but it is much more powerful, and more grateful; and is good against all forts of putrid and malign Fevers, Con∣tagious Diseases, and the Plague, as also the Scurvy, and Obstru∣ctions of the Bowels; it quenches Thirst, and restores the weakned Ferment of the Stomach, and stirs up the Appetite. Dose, à gr. iv. ad xx. It is oftentimes mixed with three parts of white Sugar. Outwardly, being rubbed upon the Gums and Teeth, it cleanses them, and preserves them from rotting.