Course of my few trials, I have not yet been able to condense it in a perfectly dry bottle.

NUMBER VI.

A Letter from Dr. FRANKLIN.

Dear Sir,

Craven-Street, April 10, 1774

In compliance with your requeft, I have endeavoured to recollect the circumstances of the American experiments I formerly mentioned to you, of raifing a fame on the furface of fome waters there:

When I paffed through New Jersey in 1764, I heard it feveral times mentioned, that by applying a lighted candle near the furface of fome of their rivers, a fudden flame would catch and fpread on the water, continuing to burn for near half à minute. But the accounts I received were so imperfect that I could form no guess at the cause of fuch an effect, and rather doubted the truth of it. I had no opportunity of feeing the experiment; but calling to fee a friend who happened to be just returned home from making it himself, I learned from him the manner of it; which was to choose a shallow place, where the bottom could be reached by a walking-ftick, and was muddy; the mud was firft to be ftirred with the stick, and when à number of small bubbles began to arife from it, the candle was applied. The flame was fo fudden and fo ftiong, that it catched his ruffle and spoiled it, as I faw.

New-Jersey having many pine-trees in different parts of it, I then imagined that fomething like a volatile oil of turpentine might be mixed with the waters from a pine-swamp, but this fuppofition did not quite fa-. tisfy me. I mentioned the fact to fome philofophical friends on my return to England, but it was not much attended to. I suppose I was thought a little too credulous.

In 1765, the Reverend Dr. Chandler received a letter from Dr. Finley, Prefident of the College in that province, relating the fame experiment. It was read at the Royal Society, Nov. 21. of that year, but not printed in the Tranfactions; perhaps, because it was thought too ftrange to be true, and fome ridicule might be apprehended if any member should attempt to repeat it in order to afcertain or refute it. The following is a copy of that account.

"A worthy gentleman, who lives at a few miles diftance, informed me, that in a certain fmall cove of a mill-pond, near his houfe, he was furprized to fee the furface of the water blaze like inflamed fpirits ; I foon after went to the place, and made the experiment with the fame fuccefs. The bottom of the creek was muddy, and when stirred up, fo as to cause a confiderabie curl on the furface, and a lighted candle held within two or three inches of it, the whole furface was in a blaze, as inftantly as the vapour of warm inflammable spirits, and continued, when strongly agitated, for the fpace of feveral feconds. It was at firft imagined to be peculiar to that place; but upon trial it was foon found, that fuch a bottom in other places exhibited the fame phenomenon. The difco

very was accidentally made by one belonging to the

mill."

I have tried the experiment twice here in England, but without fuccefs. The firft was in a flow running water with a muddy bottom. The fecond in a ftagnant water at the bottom of a deep ditch. Being fome time employed in ftirring this water, I afcribed an intermitting fever, which feized me a few days after, to my breathing too much of that foul air which I ftirred up from the bottom, and which I could not avoid while I ftooped in endeavouring to kindle it. The discoveries you have lately made of the manner in which inflammable air is in fome cafes produced, may throw light on this experiment, and explain its fucceeding in fome cafes, and not in others. With the highest esteem and respect,

I am, Dear Sir,

Your moft obedient humble fervant,

B. FRANKLIN.

NUMBER

VII.

Extract of a Letter from Mr. HENRY of Manchefter.

It is with great pleasure I hear of your intended publication on air, and I beg leave to communicate to you an experiment or two which I lately made.

Dr. Percival had tried, without effect, to diffolve lead in water impregnated with fixed air. I however thought

thought it probable, that the experiment might fuc ceed with nitrous air. Into a quantity of water impregnated with it, I put several pieces of fheet-lead, and fuffered them, after agitation, to continue immerfed about two hours. A few drops of vol. tincturė of fulphur changed the water to a deep orange colour. but not fo deep as when the fame tincture was added to a glass of the fame water, into which one drop of a folution of fugar of lead had been inftilled. The precipitates of both in the morning, were exactly of the fame kind; and the water in which the lead had been infufed all night, being again tried by the fame teft, gave figns of a ftill ftronger faturnine impregnation. Whether the nitrous air acts as an acid on the lead, or in the fame manner that fixed air diffolves iron, I do not pretend to determine. Syrup of violets added to the nitrous water became of a pale red, but on standing about an hour, grew of a turbid brown caft.

Though the nitrous acid is not often found, except produced by art, yet as there is a probability that nitre: may be formed in the earth in large towns, and indeed foflile nitre has been actually found in fuch fituations, it should be an additional caution against the ufe of leaden pumps.

I tried to diffolve mercury by the fame means, but without fuccefs.

I am, with the moft fincere efteem,