Benjamin Franklin Papers - From Joseph Priestley

I wrote to Mr. Price last post, in which I desired him to remind you of your promise to procure me Beccaria’s work, which you said you thought you could do of Mr. Delaval. Fearing he might not see you soon, I write to desire you to get it for me, if possible, without loss of time. Otherwise, I must reserve his experiments for an Appendix, for, by the references I meet with to them, I find my book absolutely must not come abroad without them. I am in such haste, as we have already begun to print, and have done five sheets. The whole work will make betwixt 400, and 500 pages 4to, and we shall not have done quite so soon as Christmas. For the same reason, I must beg you would also send me, as soon as you conveniently can, the two last numbers of the work, which I left in the hands of Dr. Watson, to be transmitted to you. I am now wholly employed in revising and correcting. I defer drawing up the account of my own experiments, till I have some more in pur[s]uance of them, and several others. In about a week I shall betake myself to experiments in good earnest, but I have no expectation of doing much more than I have done. Upon Mr. Price’s letter, I sent the mark that was actually made by a chain when a discharge was sent thro it. I have several times since I came home got three, and almost always two concentric circles, upon the metal knobs with which I make discharges. If I verify your experiments on the electrified cup, and animal fluids, may I publish them as yours, in some proper place in my work? I shall soon go about them. Have you procured the list of books written on the subject of electricity, or the remainder of Wilke’s treatise. Dr. Watson has sent me a curious tract of Johannes Franciscus Cignas which I am now digesting. In your notes [on] one of my former Numbers you say, you question whether Aeolipyle will turn the same way whether it draw in [or] throw out the water. I had tried it before I wrote [the] paragraph, you may depend upon the fact. I hope to find more of your excellent remarks upon the two numbers in your hands. I am, Dear Sir, your most obliged humble servant

Since I wrote the letter, I have made a discharge, through a chain that lay on this side of it. At the moment of the discharge, the whole appeared like a bright flame. From (a) when the chain was returned, it was thrown back as far as (b). I have tried the same several times since, laying one half of a chain parallel to the other, and marking exactly how far it reached upon the table; and always found the middle part pulled back about an inch and a half [as] if a sudden jerk had been given [to] it. Indeed it was manifest, by comparing the links with the marks, that every link had moved a little. Must not that have been effected by the links repelling one another, while the shock was passing? Is not the paper really burnt? Was not the chain made superficially hot? and does not the electric shock pass chiefly over the surfaces of bodies? so that small bodies will be melted, because they have most surface in proportion to their bulks. nb The fa[int] marks, at a distance from the rest, are not made [by] handling. They are just as the discharge left them. Indeed, you will find they are not easily effaced. nb The wire of the chain is not so thick as the marks.