Having been absent from town about a fortnight, I did not immediately recieve your letter, nor have had an oportunity of acknowledging the pleasure it gave me, until this post. You have dispell’d my doubts concerning the ballons, the accounts of which I supposed to be monstrous exaggerations, tho founded probably on some small Experiment of the kind. It is some Years since Mr. Cavendish discover’d that one species of Inflammable air (that separated from some Metals during their solution in Acids) was lighter than common air, but not I think in the enormous proportion you mention. I have seen an Account given by Ingenhouz of another Species of Inflammable Air, obtain’d from a Mixture of vitriolic Acid and Spirit of Wine, which is heavier than common air. Madison tells me, that he thinks the Inflammable air, extricated from Wood in a gun-barrel by Heat, is heavier than common air, and I should suppose this kind to be very similar to that which arises from burning straw. However Mr. Madison has made no direct Experiment and only conjectures from appearances. It is remarkable in Lettsom[’s] account that the sudden change in the pressure of the Atmosphere, the Barometer falling from 28 to 18, produced no disagreeable effect in the person exposed to it. This might be owing perhaps to the change of temperature in the Air which happen’d at the same time, the extreme cold preventing that expansion of the fluids, which we might expect to be the consequence of diminish’d pressure.

I am extremely obliged by your recommendation to so gente[el] and respectable an employment, as it is a proof of your good opinion of me, and that you interest yourself in my advancement. I have, however, small expectation of success, being not even known to any members of congress except those from our state, and confident also that it will be sollicited by many more capable of discharging it’s duties than myself. I do not know whether I ought to wish it, since it cannot assist me in procuring that Independency, which is at present the chief Object of my wishes. I do not wish for a temporary splendor, which on a reverse might render myself or my family less satisfied with a humbler Lot. I can assure you however that the Labors and Duties of this Office would be infinitely more agreeable to me than those of my profession. I have long been disgusted with the latter, have found it irksome, fatiguing and very little profitable. Nor can I think that anything more is necessary, for Discharging Well the former, than Industry and Integrity. If I was single, I should find this Office most desirable. As matters are, however agreeable it might be in possession, ‘tis likely that it would confirm me in a state of Dependancy for ever. I suppose the Acceptance of it would be construed into an Abandonment of my Profession and preclude all prospects in that Line.

Your neice’s consumption has terminated in an Increase of the family. I have heard nothing from her since her pregnancy became evident, nor have I been at Rich-neck for some months. But I was lately inform’d by Genl. Nelson that he was invited to a christening there. I am very sorry to hear that you have been yourself an Invalid, but I depend upon your prudence, and the goodness of your constitution, that you will not long continue so. Tho’ I have nothing to give in return, I shall be happy whenever your leisure can afford me a Line. Besides the pleasure of hearing from you, your new communications in Science and politics enliven our little Society. I have not yet seen Crawford’s Experiments on which he founds his Theory of the production of Heat in Inflammation, &c., tho I ardently wish for it. Mrs. McClurg presents her most respectful Compts. & I am, with perfect esteem, Dear Sir, Your much obliged hble servant