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ious. Thefe vegetables, nevertheless, remained, as to sense, equally fweet as when they were put into the vial.

We concur with the Author (of whofe accuracy we entertain not the leaft doubt) in expreffing our furprize at the refults of these laft trials. In fome of the fmall variations above noticed, errors, perhaps equal to the differences obferved, may have been produced by unknown or unheeded causes; fuch as, a variation in the quality or ftrength of the nitrous air, the temperature of the atmosphere, &c. but this obfervation cannot properly be applied to the facts in queftion. It is indeed. amazing,' as the Author obferves, that vegetables, whilst fresh and free from the leaft degree of putrefcency, fhould have fuch a noxious tendency as to fpoil the air, and render it not only useless, but fatal to animal life, and that in so short a time.'-On this head, however, we fhall propofe a few obfer

vations.

When Dr. Priestley firft difcovered the ufe of nitrous air, as a teft of the falubrity of common air, he may be thought to have made a full reparation for the lives of the many mice he had facrificed in his previous trials.-" Every perfon of feeling," he obferves on his firft notification of it," will rejoice with me in the discovery of nitrous air-which fuperfedes many experiments with the refpiration of animals; being a much more accurate teft of the purity of air *."-Before he had thus adopted it as a teft, he had experienced its truth and accuracy in numerous inftances; particularly in the cafes of fixed and inflammable air, and of all thofe fpecies of air that have been di minifhed by refpiration or other proceffes, which he had then examined. He had then juft reafons to infer, that “on whatever account air is unfit for refpiration, this fame teft is equally applicable +."

Though there has not hitherto appeared any reason to suspect the truth of the indications presented by this teft, we cannot help wishing that, on this extraordinary occafion, the Author had corroborated its teftimony by fome collateral proofs. He does not even inform us whether a candle was inftantly extinguifhed on being introduced into the air in which his flowers had been confined: though even that event would not have proved that the air was perfectly, or even to any great degree, noxious. The application of nitrous air as a teft of the falubrity of air is now become fo very extenfive, and the results

lead

Experiments and Obfervations on different Kinds of Air, vol. i. + Ibid. pag. 115.

pag. 73.

Dr. Priestley, long ago, obferved, that a candle would not burn in air, in which a fresh cabbage-leaf had remained one night. [Obfervations, &c. vol. i. pag. 51. We have found that a candle

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lead to fuch important conclufions, that it becomes neceffary, especially in a new and fingular case, to inquire whether there may not exift fome particular exceptions to the general rule; or whether it may not be poffible that air, faturated with the effluvia of certain bodies, may not thereby be rendered incapable of affecting, or being affected by, nitrous air, and yet may continue perfectly falubrious.

Though it may be true univerfally that, on the admixture of nitrous air with any kind of mephitic or perfectly noxious air, no diminution will be produced; it does not neceffarily follow that the converfe of this propofition must be likewife univerfally true; or that, in every cafe whatever, when no diminution is obferved, the air exposed to the nitrous test must neceffarily be mephitic or perfectly noxious. It was till lately univerfally believed that air, in which a candle would burn, was whole fome and fit for refpiration. Dr. Prieftley has however difcovered one remarkable exception to this general and long established teft of the purity of air. He has, by more than one procefs, reduced nitrous air into fuch a state as to perfonate common air, in this very quality, so that a candle would burn in it quite naturally; and yet he found that this air continued as highly noxious as ever. [See particularly his Obfervations on Air, vol. iii. pag. 132, &c.]

We fhall only relate fome of the refults of another clafs of the Author's experiments, made with a view to afcertain the effects of the effluvia arifing from moift and marshy foils upon air; and which are known to be the fource of the most dangerous putrid diseases.

Two ounces of black mud, taken from a ftinking morals at York, occafionally overflowed by a brook, being put into an 8 ounce vial of air, affected it fo in 12 hours as to reduce it, according to the teft of nitrous air, from about 60° or 62° to 34° or 36°. When this mud was made perfectly dry, fo as to be reduced to a powder; it affected the air which was exposed to it fo little, that the diminution, in feveral experiments, proceeded only from 62 to 60°.-But the very fame powder being again reduced to the confiftence of mud, by the addition of a little was inftantly extinguished on putting it into a quart of air in which various flowers and leaves of vegetables had remained 48 hours. This air was found to be perfectly noxious, according to the nitrous teft. The Reviewer of the prefent Article, not choofing to take fuch liberties with a moufe, as with his own proper perfon, infpired this air more than once, through a bent tube of a large bore; but was not fenfible of any inconvenience, nor did he perceive any thing particular in it. No ftrefs, however, can be laid upon this trial; as this air must have been greatly diluted by that contained in the fauces and trachea of the Experimenter.

water,

water, and inclofed in a fimilar vial of air, affected the latter fo far as to reduce the diminution from 62° to 49°; and on ftanding longer, the diminution was reduced from 62° to 29°. Again, when more water was added to this mud, fo as to swim to a confiderable height above the powder, after the latter had fubfided, the air again tried by the teft was in no inftance found to produce a greater reduction of the diminution than from 62° to 56o.

The refults of these and other experiments, which we omit, correspond with the observations of Sir John Pringle, and other practical medical writers; who have remarked that the diseases peculiar to low and marfhy fituations feldom begin to appear, till the water is fo far evaporated, as to leave a black and flimy mud; that these diseases ceafe when the bogs and marshy grounds have been drained, and are become perfectly dry;-and that, on the other hand, the danger arifing from marthes and bogs, is, in a great meafure, obviated, on their being laid wholly under water. In this laft cafe, the Author obferves that the putrid fermentation is either prevented by too much moisture; or the effluvia are abforbed in paffing through the fuperincumbent bed of water.'

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Article 9. Obfervations on the Population and Difeafes of Chester, in the Year 1774. By J. Haygarth, M. D.

In

This paper contains fome judicious and useful obfervations, which are fucceeded by feveral accurate tables of mortality, difeafes, &c. The most striking of the Author's remarks relates to the very uncommon healthinefs of the city of Chester. one of these tables, the Author has collected from different writers the proportionable number of inhabitants that die annually in various places; and, in the table that precedes it, has given the annual average, during ten years, of the deaths in the city of Chefter. From the latter, we collect that only 1 in 58 dies annually in the fix parishes within the walls, and, in the whole town collectively, I in 40: whereas from the other it appears that there die annually-at Jamaica, I white perfon in 5;-at Vienna, 1 in 191;—at London, 1 in 204;—at Edinburgh, 1 in 20, &c. We omit the ratio of deaths in other large towns, and proceed to Manchester, the last and healthieft fet down in this table, where the proportion is 1 to 28. It appears, too, that the healthinefs of the city of Chefter, within the walls, exceeds even that of any of the country parishes fet down in the abovementioned table; where we find that in the Pais de Vaud, and fome country parishes in Brandenburgh, there dies 1 in 45. The highest number here given is 1 in 54, oppofite to Stoke Damerel, in Devonshire.

The causes of this fingular degree of healthiness in Chester may, perhaps, be partly afcertained, by attending to fome pe

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culiarities

culiarities in its fituation and ftructure, which the Author accordingly defcribes; and from which it appears that it is probably exempted, in confequence of these circumftances, from two of the principal fources of difeafes; ftagnant moisture, and putrefaction. It is feated on a rifing promontory, formed of a fandy, porous rock, through which water quickly filters. The ftreets likewise defcend, in every direction, from the fummit of this rock, with a gentle declivity, to the edge of it; whence there is every way a perpendicular fall of feveral yards.-The clearness of the air too appears to be extraordinary, from a regifter kept the laft four years; during which interval, there were obferved only 32 hazy, and 6 foggy, mornings.

PAPERS relating to ELECTRICITY. Article 5. A Cure of a Mufcular Contraction by Electricity. By Miles Partington, in a Letter to William Henly, F.R.S.

The fubject of this extraordinary, and feemingly indifputable, cure, effected by electricity, was a Mifs Lingfield, who, in confequence of a cold contracted above two years before, was feized with a violent pain in the back of her head, which terminated in an obftinate contraction of the muscles of her neck, by which it was drawn down over her right fhoulder. The back part of it was twifted fo far round, that her face turned obliquely towards the oppofite fide, by which deformity fhe was difabled from feeing her feet, or the fteps as the came down ftairs.'On the other fide, fhe felt a continual and fometimes violent pain, occafioned by the extreme tenfion of the teguments, &c. on that fide. She was fubject to frequent febrile attacks; and was fometimes flightly paralytic. Notwithstanding all the endeavours of the faculty to procure her relief, the little alteration obfervable in her disorder was rather on the unfavourable fide.

Mr. Partington firft infulated and electrified her on the 18th of February; drawing strong sparks from the Maftoideus muscle and the other parts affected, for about four minutes. The electrification was repeated on the 24th and 27th, and on March the 3d, 5th, 6th, 7th, and 9th. Some amendment was perceived after the first trial; and fome advantage was evidently gained on each repetition. In confequence of particular circumftances, the procefs was afterwards continued by Mr. Henly; who daily repeated it (three evenings excepted) during the space of a fortnight; at the end of which time, the disorder appears to have been completely removed.

Mr. Henly drew strong sparks from the mufcles on both fides of the neck, during ten minutes; and likewife generally added two fhocks from a bottle containing 15 fquare inches of coated furface fully charged, through her neck and one of her arms, croffing the neck in different directions.

Article

Article 15. Sundry Papers relative to an Accident from Lightning at Purfleet, May 15, 1777;—particularly new Experiments and Obfervations on the Nature and Ufe of Conductors. By Benjamin Wilfon, F. R. S. &c.

The accident which befel the house built for the occafional accommodation of the Board of Ordnance at Purfleet is, in general, well known to our philofophical Readers. This house was furnished with a pointed conductor; at the distance of 46 feet from the point of which, a corner of the building received fome damage from a flash of lightning, which ftruck off a piece of stone, and one brick, and loofened a few other bricks; which it removed lefs than half an inch from their places. This damage, small as it is, hath rendered it problematical, with some, whether the conductor with which this houfe was furnished had executed any part of its office.

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Mr. Wilton, who had originally oppofed the erection of this and other pointed conductors at Purfleet, was led, on the prefent occafion, to make the experiments, the relation of which conftitutes the principal part of this long Article. An immense conductor was fitted up, at the expence of the Board of Ordnance, and fufpended in the Pantheon; confifting of a great number of drums covered with tinfoil, which formed a cylinder of above 155 feet in length, and above 16 inches in diameter. This, when properly charged, was intended to reprefent a thunder-cloud; and there were occafionally added to it 4800 yards of wire. A model of the Board-Houfe at Purfleet was likewise conftructed, to which was occafionally annexed a pointed, or a blunt, conductor, and which by means of weights, &c. was made to pass under the artificial cloud, with a determinate velocity, fuppofed to be equal to that with which thunderclouds in general move.-In his eftimation of this velocity, however, we muft obferve that the Author has attended only to the real, and has overlooked what we may call the relative, or angular, velocity.

It is impoffible for us to give any fatisfactory account of the various experiments made with this magnificent apparatus; or of the Author's conclufions from several of them. It may be fufficient to observe, that his inferences from them are drawn fo as to ftrengthen his former opinion with respect to the danger of employing elevated conductors, armed with pointed wires; on a fuppofition that they invite the lightning. They will not however, we apprehend, appear fo fatisfactory to others as they appear to the Author.

The firing of gunpowder by this apparatus, by the electric aura or blast, without a fpark, or the affiftance of the Leyden charge, is perhaps one of the most notable effects produced by it. Upon a staff of baked wood a ftem of brafs was fixed,

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