Benjamin Franklin Papers

To Benjamin Franklin from Jan Ingenhousz, 5 December 1780

From Jan Ingenhousz

ALS: American Philosophical Society

Vienna Dec. 5th. 1780.

Dear Friend

I had the satisfaction of being informed by a lettre of monsieur le Begue de Presle, that you continued to enjoye a good health: but as it is allways a much greater satisfaction for me to be informed of your happiness by your self, I will endeavour to procure me this pleasure the sooner by giving you some information of my self. I continue to enjoye a tolerably good state of health. Being engaged in no particular employment, I continue to delivre my self entirely to the contemplation of Nature, principaly in regard to the influence of the vegetable kingdom upon the animal and to the essential ingredients out of which our atmosphere is composed.5 I intend soon to lay before the public the result of my farther inquiries upon that important subject. My farther experiments have made me alter my opinion as to the simplicity of the effect of vegetables on air in the shade and at night. I am now convinced that they not only change a part of respirable air into äerial acid or fixed air by communicating their phlogiston to it, but that they allso emit an äerial acid or fixed air from their substances. I have investigated even the quantity of this emission. I discovred the manner by which nature produces nitrous acid in the earth out of which it has been taken; at least I have changed respirable air into this acid and made real nitre from it by the addition of vegetable alcali. But this discovery is too wighty to publish, before I can prove it by a sufficient number of decisive experiments which can only be made in the summer— I have made up of the sevral metal wires you was pleased to give me. You remembre you gave me a wire of five metals all drawn thro the same hole Viz. one, of gould, one of silver, copper steel and iron.6 I supplyed here the two others Viz. the one of tin the other of lead. I fixed these seven wires into a wooden frame at an equal distance of one an other and equaly pressed by means of screws to fix them, so that they all were of the same length as far as they were out of the wooden frame, which length was of about 5 parish inches. I got a tin box made on purpose some what longer than the row of the seven metals and about 6 inches diep. This box being filled with white wax was placed in an earthen vessel filled with boiling water. The wax being thus melted must have every where the same degree of heat, when thoroughly melted. This being done, I dipt the seven wires into this melted wax as deep as the wooden frame, by which they were all kept in a row, would atmit of. By taking them out they were covred with a coat of wax, which by the cold air soon congealed, when I found that this crust was there about of an equal thikness upon all the wires, I placed them all in a glased earthen vessel full of olive oil heated to some degrees under boiling, taking care that each wire was dipt just as far in the oil as the other, which certainty I obtained by taking a vessel which I filled to the hight of about one inch with the hot oil and plunging the wires to the bottom of this vessel. I observed carefully upon which of the wires the coat of wax did melt the soonest. But as it is not an easy thing to observe at once 7 objects, I placed, after each experiment, the wires upon a vertical line or one paralel with the wire I was to examine and marked exactely the place where the wax was remained opake or not melted. Now, as they had been all dipt alike at the same time in the same oil, it must follow, that the wire, upon which the wax had been melted the highest, had been the best conductor of heat. Having repeated many times the experiment, I found, that the silver conducted heat far the best of all other metals, next to this was copper, then gold, tin, iron, steel, Lead. I have carefully transferred the 12 first experiments upon the paper inclosed; each interstice of two black lines representing a wire, and the smal red lines representing the exact hight at which the melting of the wax had stopped in the several experiments, the horizontal line representing the extremity of the wires. It appears, that in four experiments the iron and steel had conducted alike; but as in the 8 others the iron had been a better conductor than the steel, I fancy that in those experiments, in which the wax was melted in both at the same hight, the coat of wax had been some what thicker upon the iron than upon the steel, which is not easily observable by the eye. I Suspect the same circumstance may have happened in the three experiments viz. the III the V. and the XIIth with respect to the tin Stannum— After I had very accurately observed this subject, I was curious to see, whether the seven metals were allsoo as good conductors of cold as they are of heat. But I was somewhat surprised to observe, that they did not quit the recieved heat in the same ordre as they did transmit it. The lead and tin loose their heat much sooner than the silver copper or any other metal. Iron and steel keep it the longest of all tho they admit heat less readier than all the other metals, lead excepted.— As this part of my inquiry was much more difficult to observe than the transmitting of heat, I could not hitt upon a satisfactory way of determining accurately this faculty of retaining heat. My way of observing it was to look carefully upon which of the wires the melted wax kept fluid the longest in the open air. Sometimes I dipt the extremities of the wires into Cold water, when the wax was still fluid and transparent upon them, observing in what order the wax grew cold upon the different metals— If you think this farther inquiry worth while making with more accuracy, I will still endeavour to pursue the matter. As I have no wright in claiming any merit on this head, I will make no farther use of this comparison of the conducting Power of various metals, as you, who furnish’d me with the materials and suggested me the method of making the inquiry, think proper.

I should be glad if you could inform monsieur le Begue, that I have at last recieved the four copies, bound in, of my book, which monsieur Didod did send me two months ago by the court messanger or by the imperial ambasadour.7 As I have given information lately to monsieur Didod, of my having not yet recieved them, this message will prevent unnecessary perquisitions about the parcel.

I should be glad to know by a word, whether my book was well recieved by the public in France. There is allready a German translation of it publish’d, and also a deutch one.

I have not yet had the honour of seing the Emperour since the Death of his mother.8 This unexpected Death has prevented the Emperour coming to my house with the first Lord of the bedchamber to see the experiments relating to my discoveries. Time will disclose what changement this accident may create in this country.

I recieved a lettre of monsieur Wharton dated l’orient sept. the 10th, which was put in the post office at Paris, the postage being payed, as must be done for letters goying out of France. In this letter he acquaints me, that he has just time to inform me he sets of that very day for America, he refers me to a lettre which I never recieved and which he says to have written me on August the 30th: As this letter is of material Concern for me, I should be glad if you could find it out, as I suspect it may have been send to you as the last has probably been. It may have been forgotten among your papers or those of your clerks. It could bee allso, that it was send to Dr. Bankroft or some body else with whom Mr. Wharton corresponds. I begg earnestly to be so good as to enquire about it.9 You know it is often the case, that servants doe not delivre the letters to the post office on purpose to steel the postage to be given for foreign letters.

I hope you will furnish me with some news of your country men. I see with great concern the unhappy fate of some Americans how have been sacrificed for having been found in arms after having given their parole of honour no more to engage in the conntest, and that as many of the English prisoners have met with the same fatality by way of retaliation. I hope the case of the Americans has been misrepresented in this affair as has been in many others. I am astonish’d at gen. Arnold’s defection, and wish to know the conditions which were contracted between him and gen. Clinton, which conditions will disclose the true motifs of so extraordinary a treachery. What impression has this event made in the minds of the Americans? It seems to me, that the attempt to bring back the colonies under the obedience to the mother country by bribery, treachery and severity can not operate the desired effect, even if it could produce a conquest of the whole country; for it would alienate the minds of a nation subdued by such maximes. The severity adopted by Philip the second alienated at once for ever the minds of our ancestors from the souverain, and the struggle for liberty lasted 82 years. If it must be the fate of Gr. Brittain to loose the Empire of North America, and if it be the intrest of Urope, that a country, which in less than half a century gave rise to three blody wars among the powers of Europe, should have no more any political connection with our continent, nothing is more to be wish’d than that the contest be short. I wish for some news from you on this head: you know to whom it may please for my own’s sake. However I will make no farther use of what you may entrust me with than what you allow me to make of it. I hear from others that our friend sir john1 begins to decay and to be less sollicitous about the affairs of this world, and that he longes much to have my company again.

I must begg you excuse for the length of this lettre; I would be anxious lest it should displease you for this reason, if I did not consider that I write to a brother [torn: philosopher] and a Friend. I am with respectfull affection yours

J. Ingenhousz

You know my adres is. … a Vienne en autriche

Endorsed: Dec. 5, 1780

Addressed: A Monsieur / Monsieur Benj. Franklin / a Passy pres de / Paris

[Note numbering follows the Franklin Papers source.]

5For Ingenhousz’ work on photosynthesis, published in 1779, see XXXI, 122n; XXXII, 116.

6In July, when Ingenhousz was in Paris, BF turned over to him the materials for an experiment that would test the conductivity of metals, admitting that he might never get the time to do it himself. BF asked his friend to perform the experiment and report back with the results, which he is doing in the present letter. Ingenhousz published his findings in 1785, and despite his vigorous disclaimers that the idea had been entirely BF’s, the procedure came to be known as the Ingenhousz experiment. See XXXII, 344n.

7Pierre-François Didot le jeune published the French translation of Ingenhousz’ work, Expériences sur les végétaux …, in 1780. The imperial ambassador was Comte François de Mercy-Argenteau: Larousse; Almanach Royal for 1780, p. 142.

8Maria Theresa.

9In February, 1780, Ingenhousz had entrusted 8,000 l.t. to Samuel Wharton for a mercantile venture; shortly thereafter he invested in a joint venture involving Wharton, Francis Coffyn, and Edward Bancroft. Wharton, who would collect the profits in America, promised to send remittances through BF. It would be years before Ingenhousz saw even a penny, and his letters to BF on this matter become increasingly frantic. On June 11, 1785, he sent BF a memorandum outlining events; this is at the APS and fully summarized in Hays, Calendar, III, 262–3. See also Francis Coffyn’s letter below, Dec. 15.


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