confumed; which on being put on a piece of ignited charcoal, is reduced, at least in part, to a metallic ftate, The Author confidering the great quantity of fulphur contained in the Derbyfhire lead ores, where about 10,000 tuns are fmelted annually, proposes to the confideration of the lead fmelters the practicability of collecting it; both as a lucrative bufinefs to themselves, and a great faving to this country, where, it feems, we at prefent import the fulphur we ufe. For this purpofe, he fuggefts' the poffibility of collecting it, in long, large, and winding horizontal chimneys, connected with the furnaces in which the ore is roafted in the fame manner as is practifed in Saxony, where arfenic is procured by a fimilar contrivance; the arfenical vapour being condenfed, and attaching itself, like foot, to the fides of the chimney; from which the arfenic is, from time to time, fwept out.

At the end of this paper, the Author relates fome experiments from which it appears that, though the furface of pure melted lead becomes covered with a pellicle of various colours; yet thefe appearances do not occur if a small portion of tin be mixed with the lead, even when the weight of the tin scarce exceeds the roth part of the weight of the lead. Zinc poffeffes the fame property, in this particular refpect, as tin. After the tin has been reduced to a calx, by the continuance of the heat, the lead again acquires its property of forming colours; which fucceffively appear in the following order: yellow, purple, blue, yellow, purple, green, pink, green, pink, green. The rationale of these appearances may be deduced from the well-known experiments and theory of Sir Ifaac Newton, lately illuftrated and confirmed by Mr. Delaval, in his ingenious Experimental Enquiry refpecting the changes of colours in bodies *.

MISCELLANEOUS ARTICLES. Article 26. An Account of the Island of St. Miguel. By Mr. Francis Maffon,

This island is one of the principal of the Azores. The only particulars relating to it, that can entitle this account of it to a place in the Philofophical Tranfactions, are contained in a general description of fome fountains, from which the water boils up fo hot, that a perfon cannot dip his finger into it without being scalded.' A fteam likewife rifes, to a confiderable height, from several apertures, which is fo hot, that no one can approach it with the hand. In other places, fays the Author, a perfon would think that a hundred fmiths bellows were blowing altogether, and fulphureous steams iffuing out [iffue out] in thousands of places, fo that native fulphur is found in

See an account of that work in the 57th volume of our Review, P. 221.

REV. Jan. 1778.

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every chink, and the ground covered with it like hoar froft; even the bushes that happen to lie near these places are covered with pure brimftone, condenling from the fteam that iffues out of the ground, which in many places is covered over with a fubftance like burnt alum." Though the Author appears to have been in poffeffion of a thermometer; no account is given of the actual temperature of thefe waters.

Near thefe boiling fountains, there are feveral cold mineral fprings; two of which are faid to fend forth waters ⚫ which have a very strong mineral quality, of an acid tafte, and bitter to the tongue.'-Seven fpecimens of thefe and other waters have been fent home, and are enumerated at the end of this Article. The firft of thefe was taken from one of these cold fountains; which is defcribed as giving a frong acid water.'-As this Arong acid water appears to us a very great curiofity, we could have wifhed that its analyfis had been fubjoined to this Atticle as well as, indeed, that of the hot waters above mentioned, which are faid to poffefs confiderable virtues in the cure of the dead pally, eruptions, and more particularly the gout. While the Author refided near thefe waters, feveral old gentlemen, who were quite worn out with the faid diforder, were ufing the waters, and had received incredible benefit from them.' He accordingly hints, that' fhould any person venture so far for his health, a fmall stock of the fuperfluities of life only need to be laid in, as the island yields every neceffary, and the climate is very temperate.

Article 27. An Account of a remarkable Imperfection of Sight. In a Letter from Mr. J. Scott, &c.

The person who here communicates feveral extraordinary particulars of an hereditary infirmity in the vifual organs, with refpect to colours, can fee objects at a distance, and diftinguish their form and bulk as well as most men: but fuch is his fin

gular idiosincrafy with refpect to their colour, that he declares, though his bufinefs was behind a counter many years, where he had to do with a variety of colours'. he does not know any green in the world; a pink colour, and a pale blue are alike. He has often thought a full red and a full green the fame, or a good match: though he can difcern the difference between yellow and a full blue. He relates an anecdote of his having been offended at an intended fon-in-law's having entered his houfe, on the day preceding his marriage, in a new fuit of cloaths, which appeared as much a black to his eyes, as any black that ever was dyed; while the gentleman had actually decorated himfelf with a fine rich claret-coloured dress.

We have called this imperfection hereditary; but, like fexdigitifm, it appears to have affected only fome individuals of his family. He derived it from his father; but his mother had

not this imperfection, and yet her own brother had the like impediment with himfelf. This is fomewhat fingular; unless his father and mother were related to each other before marriage. One of his fifters knows.colours, the other does not; the laft has two fons who have this imperfection, and a daughter who is free from it. His own fon and daughter know all colours without exception.

Article 40. Defeription of a most effectual Method of fecuring Buildings against Fire, invented by Charles Lord Viscount Mahon, F. R.S.

As it is impoffible to abridge this interefting Article; and as the noble inventor has not in it explained the principles on which his method is founded; we fhall confine ourselves to his account of two trials of it, made in the presence of the Prefident and fome of the Fellows of the Royal Society, the LordMayor and Aldermen of London, several of the foreign ministers, and others.

The lower room of a building, which was about 26 feet long, by 16 wide, was filled with fhavings and faggots, which were fet on fire. The heat was fo intenfe, that the glass of the windows was melted, like so much common fealing-wax, and run down in drops; yet the flooring boards of that very room were not burnt through, nor was one of the fide timbers, floorjoifts, or cieling-joifts, damaged in the fmallest degree; and the perfons who went into the room immediately over the room filled with fire, did not perceive any ill effects from it whatever; even the floor of that room being perfectly cool during that enormous conflagration immediately underneath.'

To repréfent a timber-built town on fire, and to fhew how effectually even a wooden building, fecured in this manner, would ftop the progrefs of the flames; a kind of timber building (of full 50 feet in length, and of three ftories high in the middle) had been erected, quite clofe to one end of the fecured wooden houfe. The former was filled and covered with above 1100 large kiln faggots, and feveral loads of dry fhavings; and the whole pile was fet on fire. The event is thus related: . The height of the flame was no less than 87 feet perpendicular from the ground; and the grafs upon a bank at 150 feet from the fire was all fcorched: yet the fecured wooden building, quite contiguous to this vaft heap of fire, was not at all damaged, except fome parts of the outer coat of plafter work.'An attempt was next made to burn a wooden ftaircafe, fecured according to the inventer's method: but it refifted the flames, as if it had been conftructed of fire-ftone. Since this experiment, five other, ftill fronger, fires have been made on and under it; the whole fpace having been filled with fhavings

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fhavings and large faggots: but this Afbeftine ftair-cafe is ftill ftanding, and is but little damaged.

The noble Inventor of this method proposes, in a fhort time, to give the world an account, in detail, of many other experiments on this important fubject; and of the application of his method to different kinds of buildings, and to the different conftituent parts of a house. He means likewife to add a full explanation of the principles upon which it is founded, and the reasons for its certain and surprising success.

Article 50. Track of his Majefty's armed Brig, Lyon, from England to Davis's Streights, and Labrador, &c. By Lieutenant Richard Pickerfgill, &c.

This Article is digested in a tabular form, and contains the daily observations made for determining the longitude by the fun and moon, the error of the common reckoning, the variation of the compafs, dip of the needle, &c. as obferved during the voyage in 1776. At the end of the paper, the Author, without meaning any perfonal reflection,' animadverts on the accounts given by others of this part of the world, fo little known, and fo terribly reprefented. Having heard fuch dreadful ftories of thefe countries,' he adds, I cannot help remarking it, as a circumftance equally foolish and ridiculous; tending to mislead those who, from a laudable principle, would be benefactors to their country, but are deterred from it by fuch representations and he declares his intention of publishing, in a fhort time, his obfervations on the ice, the atmosphere, the land of Forbifher, and the probability of a North-west paffage *.

The remaining papers in this volume are-Article 28. Containing an Account of Baptifms, Marriages, and Burials, during 40 Years, in the Parish of Blandford Forum, Dorset; by Richard Pulteney, M. D. F. R. S.; where it appears that, on an average, there only dies 1 in 39 yearly.-Art. 30. Aftronomical Obfervations made in the Auftrian Netherlands, in the Years 1773, 1774, and 1775; by Nathaniel Pigott, Efq; F. R. S. &c.-Art. 34. An Account of the Blue Shark, together with a Drawing of the fame; by W. Watson, jun. M. D. F. R. S.— Art. 35 A Defcription of the Exocoetus Volitans, or Flying Fifb;

It is to be feared that we shall have no more of thefe papers: Mr. P. lately loft his life by the overfetting of a boat on the Thames, as he was going on board a privateer, of which he had the command. The mention of this accident, naturally fuggets to us the melancholy idea of a ftill greater lofs which the public bath fuftained by the unfortunate death of, perhaps, the greatest navigator that ever exited: Need we add the celebrated name of Capt. Cook ?— The reft was told in the London Gazette of January 11, 1780.

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by Thomas Brown, Surgeon, near Glasgow, &c.-Art. 45. Obfervations on the Solar Eclipfe which happened June 24. 1778; by William Wales, F. R. S. &c.-and Art. 46. An Account of the fame Eclipfe obferved at Leicester; by the Rev. Mr. Ludlam.

ART. VII. Philofophical Obfervations on the Senfes of Vifion and Hear. ing to which are added, a Treatise on Harmonic Sounds, and an Ejay on Combuftion and Animal Heat. By J. Elliot, Apothecary. 8vo. 3 s. 6d. fewed. Murray. 1780.

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HIS collection of philofophical papers, and particularly thofe relating to Combuftion and Animal Heat, are the productions of a perfon evidently fmitten with the love of philofophy; and courting her, not unfuccefsfully; partly in the way of experiment, but principally (though, as it feems, not through choice) in the mode of theory and fpeculation.

In the first fection, which relates to Vifion, the Author defcribes the appearances that occurred in an experiment made with a view to afcertain the fenfations that would be excited in the Retina, without the action of light upon it; by means of a violent and long-continued mechanical preffure made with the hands on the eye-balls, in the direction of their axes. A concave hemifphere of light firft appears, chequered often in a very regular manner, with dark and lefs lucid intervals. Other appearances present themselves in fucceffion, on increafing the preffure till the eyes become quite hot; at which time the lucid appearance nearly equals that which is experienced at noon. day, when the eyes are open. The reader will be in pain for the hardy Experimenter, as he proceeds in reading the Author's account of the fucceeding fenfations, till the time when the luminous appearances totally vanished; fo as not to be renewed on the continuance, or even increafe, of the preffure. At this time the retina has loft all fenfation; fo that on removing the hands, and opening the eyes, the Author had the comfort to find himself totally blind; not being able to perceive the direct light of the fun itfelf. At length, however, but by degrees, the fenfibility of the organ is restored.

This experiment,' fays the Author, is very painful,' (and, we will add, not a little hazardous) and it is not every one that would choose to repeat it after me, with the requifite care.' It is, we believe, a unique, and, we hope, will continue fo. For though, now that it has been made, we are much obliged to the Author for it; as fome of the appearances may throw new lights on certain difputed points relative to vifion; yet we would advise the curious reader to content himfelf with meditating only on the particulars that the Author has given of this fingular experiment,

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