I received your Favour of May 1. with the Pamphlet for which I am obliged to you. It is well written. I hope in time that the Friends to Liberty and Humanity will get the better of a Practice that has so long disgrac’d our Nation and Religion.

A few Days after I receiv’d your Packet for M. Dubourg, I had an Opportunity of forwarding it to him by M. Poissonnier, a Physician of Paris, who kindly undertook to deliver it. M. Dubourg has been translating my Book into French. It is nearly printed, and he tells me he purposes a Copy for you.

I shall communicate your judicious Remark relating to Air transpir’d by Patients in putrid Diseases to my Friend Dr. Priestly. I hope that after having discover’d the Benefit of fresh and cool Air apply’d to the Sick, People will begin to suspect that possibly it may do no Harm to the Well. I have not seen Dr. Cullen’s Book: But am glad to hear that he speaks of Catarrhs or Colds by Contagion. I have long been satisfy’d from Observation, that besides the general Colds now termed Influenza’s, which may possibly spread by Contagion as well as by a particular Quality of the Air, People often catch Cold from one another when shut up together in small close Rooms, Coaches, &c. and when sitting near and conversing so as to breathe in each others Transpiration, the Disorder being in a certain State. I think too that it is the frowzy corrupt Air from animal Substances, and the perspired Matter from our Bodies, which, being long confin’d in Beds not lately used, and Clothes not lately worne, and Books long shut up in close Rooms, obtains that kind of Putridity which infects us, and occasions the Colds observed upon sleeping in, wearing, or turning over, such Beds, Clothes or Books, and not their Coldness or Dampness. From these Causes, but more from too full Living with too little Exercise, proceed in my Opinion most of the Disorders which for 100 Years past the English have called Colds. As to Dr. Cullen’s Cold or Catarrh à frigore, I question whether such an one ever existed. Travelling in our severe Winters, I have suffered Cold sometimes to an Extremity only short of Freezing, but this did not make me catch Cold. And for Moisture, I have been in the River every Evening two or three Hours for a Fortnight together, when one would suppose I might imbibe enough of it to take Cold if Humidity could give it; but no such Effect followed: Boys never get Cold by Swimming. Nor are People at Sea, or who live at Bermudas, or St. Helena, where the Air must be ever moist, from the Dashing and Breaking of Waves against their Rocks on all sides, more subject to Colds than those who inhabit Parts of a Continent where the Air is dryest. Dampness may indeed assist in producing Putridity, and those Miasms which infect us with the Disorder we call a Cold, but of itself can never by a little Addition of Moisture hurt a Body filled with watry Fluids from Head to foot.

I hope our Friend’s Marriage will prove a happy one. Mr. and Mrs. West complain that they never hear from him. Perhaps I have as much reason to complain of him. But I forgive him because I often need the same kind of Forgiveness. With great Esteem and sincere Wishes for your Welfare, I am, Sir, Your most obedient humble Servant