I shook the phial often, and threw many streams of air on the blood, as I have often practised with success for impregnating water; but could not perceive the smallest signs of coagulation, although it stood in an atmosphere of fixed air 20 minutes or more. I then uncorked the bottles, and poured off about oz. ii to which I added about 6 or 7 gtts of spirit of vitriol, which coagulated it immediately. I set the remainder in a cold place and it coagulated, as near as I could judge, in the same time that blood would have done newly drawn from the vein.
P. 82. Perhaps the circ.u.milance of putrid vegetables yielding all fixed and no inflammable air may be the causes of their proving so antiseptic, even when putrid, as appears by Mr. Alexander"s Experiments.
P. 86. Perhaps the putrid air continually exhaled may be one cause of the luxuriancy of plants growing on dunghills or in very rich soils.
P. 146. Your observation that inflammable air consists of the union of some acid vapour with phlogiston, puts me in mind of an old observation of Dr. Cullen, that the oil separated from soap by an acid was much more inflammable than before, resembling essential oil, and soluble in V. sp.
I have tried fixed air as an antiseptic taken in by respiration, but with no great success. In one case it seemed to be of service, in two it seemed indifferent, and in one was injurious, by exciting a cough.
NUMBER V.
_Extract of a Letter from Mr. WILLIAM BEWLEY, of GREAT Ma.s.sINGHAM, NORFOLK._
March 23, 1774.
Dear Sir,
When I first received your paper, I happened to have a process going on for the preparation of _nitrous ether_, without distillation.[25] I had heretofore always taken for granted that the elastic fluid generated in that preparation was _fixed_ air: but on examination I found this combination of the nitrous acid with inflammable spirits, produced an elastic fluid that had the same general properties with the air that you unwillingly, though very properly, in my opinion, term _nitrous_; as I believe it is not to be procured without employing the _nitrous_ acid, either in a simple state, or compounded, as in _aqua regia_. I shall suggest, however, by and by some doubts with respect to it"s t.i.tle to the appellation of _air_.
Water impregnated with your nitrous air _certainly_, as you suspected from it"s taste, contains the nitrous acid. On saturating a quant.i.ty of this water with a fixed alcali, and then evaporating, &c. I have procured two chrystals of nitre. But the princ.i.p.al observations that have occurred to me on the subject of nitrous air are the following. My experiments have been few and made by s.n.a.t.c.hes, under every disadvantage as to apparatus, &c. and with frequent interruptions; and yet I think they are to be depended upon.
My first remark is, that nitrous air does not give water a sensibly acid impregnation, unless it comes into contact, or is mixed with a portion of common or atmospherical air: and my second, that nitrous air princ.i.p.ally consists of the nitrous acid itself, reduced to the state of a _permanent_ vapour not condensable by cold, like other vapours, but which requires the presence and admixture of common air to restore it to its primitive state of a liquid. I am beholden for this idea, you will perceive, to your own very curious discovery of the true nature of Mr.
Cavendish"s _marine_ vapour.
When I first repeated your experiment of impregnating water with nitrous air, the water, I must own tasted acid; as it did in one, or perhaps two trials afterwards; but, to my great astonishment, in all the following experiments, though some part of the fact.i.tious air, or vapour, was visibly absorbed by the water, I could not perceive the latter to have acquired any sensible acidity. I at length found, however, that I could render this same water _very_ acid, by means only of the nitrous air already included in the phial with it. Taking the inverted phial out of the water, I remove my finger from the mouth of it, to admit a little of the common air, and instantly replace my finger. The redness, effervescence, and diminution take place. Again taking off my finger, and instantly replacing it, more common, air rushes in, and the same phenomena recur. The process sometimes requires to be seven or eight times repeated, before the whole of the nitrous _vapour_ (as I shall venture to call it) is condensed into nitrous _acid_, by the successive entrance of fresh parcels of common air after each effervescence; and the water becomes evidently more and more acid after every such fresh admission of the external air, which at length ceases to enter, when the whole of the vapour has been condensed. No agitation of the water is requisite, except a gentle motion, just sufficient to rince the sides of the phial, in order to wash off the condensed vapour.
The acidity which you (and I likewise, at first) observed in the water agitated with nitrous air _alone_, I account for thus. On bringing the phial to the mouth, the common air meeting with the nitrous vapour in the neck of the phial, condenses it, and impregnates the water with the acid, in the very act of receiving it upon the tongue. On stopping the mouth of the phial with my tongue for a short time and afterwards withdrawing it a very little, to suffer the common air to rush past it into the phial, the sensation of acidity has been sometimes intolerable: but taking a large gulph of the water at the same time, it has been found very slightly acid.--The following is one of the methods by which I have given water a very strong acid impregnation, by means of a mixture of nitrous and common air.
Into a small phial, containing only common air, I force a quant.i.ty of nitrous air at random, out of a bladder, and instantly clap my finger on the mouth of the bottle. I then immerse the neck of it into water, a small quant.i.ty of which I suffer to enter, which squirts into it with violence; and immediately replacing my finger, remove the phial. The water contained in it is already _very_ acid, and it becomes more and more so (if a sufficient quant.i.ty of nitrous air was at first thrown in) on alternately stopping the mouth of the phial, and opening it, as often as fresh air will enter.
Since I wrote the above, I have frequently converted a small portion of water in an ounce phial into a weak _Aqua fortis_, by repeated mixtures of common and nitrous air; throwing in alternately the one or the other, according to the circ.u.mstances; that is, as long as there was a superabundance of nitrous air, suffering the common air to enter and condense it; and, when that was effected, forcing in more nitrous air from the bladder, to the common air which now predominated in the phial--and so alternately. I have wanted leisure, and conveniences, to carry on this process to its _maximum_, or to execute it in a different and better manner; but from what I have done, I think we may conclude that nitrous air consists princ.i.p.ally of the nitrous acid, phlogisticated, or otherwise so modified, by a previous commenstruation with metals, inflammable spirits, &c. as to be reduced into a durably elastic vapour: and that, in order to deprive it of its elasticity, and restore it to its former state, an addition of common air is requisite, and, as I suspect, of water likewise, or some other fluid: as in the 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.
Craven Street, April 10, 1774.
Dear Sir,
In compliance with your request, I have endeavoured to recollect the circ.u.mstances of the American experiments I formerly mentioned to you, of raising a flame on the surface of some waters there.
When I pa.s.sed through New Jersey in 1764, I heard it several times mentioned, that by applying a lighted candle near the surface of some of their rivers, a sudden flame Would catch and spread on the water, continuing to burn for near half a minute. But the accounts I received were so imperfect that I could form no guess at the cause of such an effect, and rather doubted the truth of it. I had no opportunity of seeing the experiment; but calling to see 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-stick, and was muddy; the mud was first to be stirred with the stick, and when a number of small bubbles began to arise from it, the candle was applied. The flame was so sudden and so strong, that it catched his ruffle and spoiled it, as I saw. New-Jersey having many pine-trees in different parts of it, I then imagined that something like a volatile oil of turpentine might be mixed with the waters from a pine-swamp, but this supposition did not quite satisfy me.
I mentioned the fact to some philosophical 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, President of the College in that province, relating the same experiment.
It was read at the Royal Society, Nov. 21, of that year, but not printed in the Transactions; perhaps because it was thought too strange to be true, and some ridicule might be apprehended if any member should attempt to repeat it in order to ascertain or refute it. The following is a copy of that account.
"A worthy gentleman, who lives at a few miles distance, informed me that in a certain small cove of a mill-pond, near his house, he was surprized to see the surface of the water blaze like inflamed spirits. I soon after went to the place, and made the experiment with the same success.
The bottom of the creek was muddy, and when stirred up, so as to cause a considerable curl on the surface, and a lighted candle held within two or three inches of it, the whole surface was in a blaze, as instantly as the vapour of warm inflammable spirits, and continued, when strongly agitated, for the s.p.a.ce of several seconds. It was at first imagined to be peculiar to that place; but upon trial it was soon found, that such a bottom in other places exhibited the same phenomenon. The discovery was accidentally made by one belonging to the mill."
I have tried the experiment twice here in England, but without success.
The first was in a slow running water with a muddy bottom. The second in a stagnant water at the bottom of a deep ditch. Being some time employed in stirring this water, I ascribed an intermitting fever, which seized me a few days after, to my breathing too much of that foul air which I stirred up from the bottom, and which I could not avoid while I stooped in endeavouring to kindle it.--The discoveries you have lately made of the manner in which inflammable air is in some cases produced, may throw light on this experiment, and explain its succeeding in some cases, and not in others. With the highest esteem and respect,
I am, Dear Sir,
Your most obedient humble servant,
B. FRANKLIN.
NUMBER VII.
_Extract of a Letter from_ Mr. HENRY _of_ Manchester.
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 dissolve lead in water impregnated with fixed air. I however thought it probable, that the experiment might succeed with nitrous air. Into a quant.i.ty of water impregnated with it, I put several pieces of sheet-lead, and suffered them, after agitation, to continue immersed about two hours. A few drops of vol. tincture of sulphur changed the water to a deep orange colour, but not so deep as when the same tincture was added to a gla.s.s of the same water, into which one drop of a solution of sugar of lead had been instilled. The precipitates of both in the morning, were exactly of the same kind; and the water in which the lead had been infused all night, being again tried by the same test, gave signs of a still stronger saturnine impregnation--Whether the nitrous air acts as an acid on the lead, or in the same manner that fixed air dissolves 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 cast.
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 fossile nitre has been actually found in such situations, it should be an additional caution against the use of leaden pumps.
I tried to dissolve mercury by the same means, but without success.
I am, with the most sincere esteem,
Dear Sir,
Your obliged and obedient servant,
THO. HENRY.
_FINIS._
FOOTNOTES:
[15] See Dr. Falconer"s very useful and ingenious treatise on the Bath water, 2d edit. p. 313.
[16] May, 1772.
[17] Vid. Mr. White"s useful treatise on the management of pregnant and lying-in women, p. 279.
[18] See the author"s observations on the efficacy of external applications in the ulcerous sore throats, Essays medical and experimental, Vol. I. 2d edit. p. 377.
[19] The author of these observations.
[20] Directions for impregnating water with fixed air, in order to communicate to it the peculiar spirit and virtues of Pyrmont water, and other mineral waters of a similar nature.