Benjamin Franklin Papers

To Benjamin Franklin from Joseph Priestley, 24 June 1782

From Joseph Priestley

ALS: Connecticut Historical Society

Birmingham 24 June 1782.

Dear Sir

You have made me very happy by your letter,4 as I find by it that, notwithstanding the unpleasing state of Politicks, your usual humour and pleasantry has not forsaken you. I am only concerned that you have not mentioned the case of my friend Mr Russell, about which I wrote to you so particularly. But I have taken the liberty to assure him, that, notwithstanding this omission, I am as confident you have not neglected the business, as if you had given me the most express assurance of it. One line, however, informing me what you think of the case, will give me great satisfaction.5

Having at length got sunshine, I am busy in prosecuting the experiments about which I wrote to you, and shall soon draw up an account of them for the Royal Society.6

Please to inform the Duc De Rochefocault, whose civilities to me I remember with pleasure, that my experiments are certainly inconsistent with Mr Lavoisier’s supposition, of there being no such thing as phlogiston, and that it is the addition of air, and not the loss of any thing, that coverts a metal into a calx. In their usual state calces of metals do contain air, but that may be expelled by heat; and after this I reduce them to a perfect metallic state by nothing but inflammable air, which they imbibe in toto, without any decomposition. I lately reduced 101 Ounces measures of this air to two by calx of lead, and that small remainder was still inflammable.

I explain Mr Lavoisier’s experiments by supposing that precipitate per se contains all the phlogiston of the mercury, but in a different state; but I can shew other calces which also contain more phlogiston than the metals themselves. That mercury, in its metallic state, does contain phlogiston, or inflammable air, is evident from the production of nitrous air & by the solution of it in spirit of nitre, and I make nitrous air from nothing but nitrous vapour and inflammable air, so that it indisputably consists of those two ingredients.

I have already ascertained the proportion of inflammable air that enters into the composition of lead, tin, copper, and silver, and am proceeding to the other metals as fast as I can. When the whole is completed, I shall give you a farther account of it.

I am exceedingly concerned to find that it is so difficult a thing to make peace; but I hope that before the campaign be over all parties will have had enough of war, and be sensible that they will gain nothing by continuing it. If I had any voice in the business, the prospect of seeing you once more in this country would be a strong additional motive to accelerate the negotiations.

With the greatest respect, and every good wish, I am, Dear Sir yours sincerely

J Priestley

P.S. If you should think it proper, I have no objection to your sending a Copy of my former letter to Rosier’s Journal, as a general outline of what I am doing.7 I wish to have every new fact to be as speedily, and as generally known as possible.

Addressed: To / Doctor Franklin / Passy, / near Paris

Notation: Priestley. 24 June 1782.

[Note numbering follows the Franklin Papers source.]

4Of June 7, above.

5William Russell (1740–1818), a merchant, political reformer, and staunch supporter of Priestley’s, had property claims in Maryland: DNB; F. W. Gibbs, Joseph Priestley: Adventurer in Science and Champion of Truth (London and Edinburgh, 1965), pp. 139, 170. Priestley’s previous letter discussing the case has not been located. On Sept. 18, 1783, Samuel Chase in London acknowledged receiving from BF a recommendation of Russell written on July 15, 1782. BF’s letter had only arrived in March, 1783, however, by which time the order had already been given to sell Russell’s property. According to Chase, that sale had subsequently been postponed. APS.

6“Experiments relating to Phlogiston, and the seeming Conversion of Water into Air,” Phil. Trans., LXXIII (1783), 398–434. Priestley’s earlier letters describing some of these experiments are missing; see BF to Priestley, June 7.

7Priestley’s letter was not published in the abbé Rozier’s Jour. de physique for either 1782 or 1783.

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