Benjamin Franklin Papers
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From Benjamin Franklin to John Hawkesworth, 8 May 1772

To [John Hawkesworth2]

ALS: Yale University Library

London, May 8. 1772

Dear Sir

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.3 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.4 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.5 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.6 Being ever, my dear Friend, Yours most affectionately

B Franklin

[Note numbering follows the Franklin Papers source.]

2The author and teacher, an old friend of BF, for whom see above, IX, 265 n and subsequent volumes.

3For Dr. David MacBride (1726–78), a noted medical investigator, see the DNB; “fixed air” is explained in a note on BF to Priestley above, May 4. The particular experiments to which BF refers are described in MacBride’s Experimental Essays on Medical and Philosophical Subjects (3rd ed., London, 1776), pp. 70–3, 86–7, 130–1, 147.

4Pyrmont water, so called from a spa in northern Germany, was a naturally carbonated water, as distinct from the artificially “impregnated” water that BF referred to in his letter just cited. For Priestley’s experiments with mixing the “two Sorts of this Air” produced by putrefaction and effervescence see his Experiments and Observations on Different Kinds of Air (2nd ed., corrected; 3 vols., London, 1775–84), 1, 98–101. Dr. William Hey (1736–1819), Priestley’s acquaintance, was an able surgeon and medical experimenter; see the DNB. Hey’s letter of the previous February, describing his use of a clyster filled with “fixed air” or carbon dioxide, appeared as an appendix to Priestley’s “Observations on Different Kinds of Air,” Phil. Trans., LXII (1772), 257–62.

5The case may or may not have been one of cancer in the modern sense. Cancerous sores, as far as we can discover, were not yet clearly distinguished from cankers, in other words gangrenous or ulcerating sores.

6For Hawkesworth’s reply see below under May 15.

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