Dining abroad yesterday, and not coming home till 12 at Night, I did not get your Letter in time to answer it by the Return of the Post as you desired.

Dr. McBride of Dublin some time since discovered that putrid Flesh could not only be render’d sweet, but its Firmness restor’d, by immersing it in Fix’d Air; which is Air that has made part of the solid Substance of Bodies, and is separated and set at Liberty from them in their Dissolution, or Fermentation, or Effervescence with other Bodies. This Air is not fit for Breathing; Flame is extinguish’d by it; and, taken into the Lungs, it instantly extinguishes animal Life: But taken into the Stomach is deemed salutary, as in Pyrmont Water which contains much of it. Dr. Priestly discovered that two Sorts of this Air, one produc’d by suffering dead Mice to putrify under a Glass, the other by the Effervescence of Chalk and Water with a small Quantity of Acid or Spirits of Vitriol, in either of which Airs living Mice being put would instantly die, yet the two being mix’d both became good common Air, and Mice breath’d in the Compound freely. From his own and Dr. Macbride’s Experiments (who thought Fix’d Air would prevent or cure the Sea Scurvey) he was persuaded it might be of use in Mortifications. But of this there has yet been only a single Experiment. A Physician of his Acquaintance at Leeds wrote to him while he was lately in Town, that a Person dying as was thought of a putrid Fever, with all the Symptoms of a Mortification in the Bowels, had been suddenly relieved and recovered by the Injection of fix’d Air as a Clyster. These are all our present Premises; upon which you can judge as well as I how far one may expect the same fix’d Air will be of Service apply’d to a Cancer. But since you ask my Opinion; as the Case may otherwise be desperate and we know of no Danger in the Trial, I should be for trying it. I would first syringe the Sore strongly with warm Water impregnated with fix’d Air, so as to cleanse well the Part. Then I would apply to it a Succession of Glasses fill’d with Fix’d Air, each Glass to remain till the Sore had absorb’d the fix’d Air contain’d in it. It would require a long Description to explain the readiest Methods of obtaining the Air, applying it, and impregnating the Water with it; and perhaps I might not make myself clearly understood. The best Way is to show it, which I will do either here, or at Bromley if you desire it. Being ever, my dear Friend, Yours most affectionately