Description of a White Earth of which bread is made. From the German Ephemerides. IN N the lordship of Mofcaw, in the Upper Lufatia, a fort of white earth is found, of which the poor, urged thereto, no doubt, by the calamities of the wars in thofe parts, now make bread. It is taken out of a hill where they formerly worked at faltpetre; when the fun has fomewhat warmed the earth, it cracks, and fmall white globules proceed from it as meal; it does not ferment alone, but only when mixed with meal. M. Sarlitz, a Saxon gentleman, was pleafed to inform us, that he has feen perfons who, in a great meafure, lived upon it for fome time; he affures us, that he procured bread to be made of this earth alone, and of different mixtures of earth and meal, and that he even kept fome of this bread by him upwards of fix years: he further fays, a Spaniard told him, that this earth is alfo found near Gironne in Catalonia. The practice of burning Sulphur in hogsheads for preserving wine, accounted for by a new and curious experiment. I F two or three drops of the oil of tartar are poured into half a glafs of very fine red wine, the wine will lofe its red colour, and become opaque and yellowish as turned and pricked wine; but if two or three drops of the fpirit of fulphur, which is a very firong acid, are afterwards poured into the glafs, the fame wine will entirely refume its beautiful red colour; whence the reafon is enfily perceived, why. fulphur is An account of a very extraordinary degree of artificial Cold produced at Petersbourgh, by Dr. Himsel Extracted from an article in the Philosophical Transactions. N the 14th of December an 1759, the weather was fo cold at Petersbourgh, that the quickfilver in De Life's thermometer, fell to 250 degrees. On this day was produced artificial cold by a mixture of fpirit of nitre with fnow, as in Farenheit's experiment, and the thermometer being plunged in it, the quickfilver funk to 470 degrees. At this point it remained fixed in the open air near a quarter of an hour, and might have remained fo longer, but after that time it was carried into a warm room, where it foon began to rife. Upon a repetition of this experiment in the prefence of feveral profeffors, the giafs was broken as foon as the mercury, which fell to 500 degrees, appeared to be fixed, and it was found frozen into a folid malleable body, which being, hammered, extended its furface like other metals, but recovered its fluidity foon after, being expofed to the open air, tho' the degree of natural cold was 199. This frozen quickfilver took up lefs fpace than when it was flui, and funk to the bottom of quick • Forty degrees below the freezing point in Farenheit's thermometer is equal to 210 degrees of De Life's. filv et filver unfrozen; but all other fluids take up more space when they are frozen, than before, and their ice fwims on the furface of the fluid matter of which it is the congealation. greateft poffible degree of cold, than fpeedy evaporation often repeated upon the fame fubftance. The fpirit called Ether, is the most volatile now known, and if the bulk of a thermometer be dipped in this fpirit, and as foon as taken out be blowed upon with a pair of bellows till it is dry, then dipped again, and blowed upon as before, in a quick and uninterrupted fucceffion, the quickfilver will be foon frozen. By the Ruffian experiments, the reports of travellers of hitherto unfuspected veracity, are proved to be falfe; for they have affirmed, that they found the mercury frozen in their thermometers when the cold was equal to 200 degrees, but thefe experiments concur to prove that it does not become folid till it falls near 3900 degrees lower. They affirm alfo, that the thermometer becomes useless, as foon as the quickfilver is frozen; but thefe experiments fhew, that, though folid, it will yet defcend with a greater degree of cold, for after it had fallen to 554 degrees, which is 54 beyond the point at which it freezes, it fell to 1260, which was 70 degrees lower upon producing a more intenfe degree of cold, by adding more fnew to the mixture, and pouring oil of vitricl upon it. It muft, however, be obferved, that diftilled mercury was ufed in thefe experiments, and that if the quickfilver be adulterated with lead, it may, perhaps, fooner become folid by cold, than if it is pure *. Upon other repetitions of the experiment, when the quickfilver fell io 495 degrees, fome fpirit of the fea falt was poured into the mixture of fpirit of nitre and fnow, upon which the quickfilver fell to 554 degrees. Some more fnow being ftill added, and fome oil of vitriol poured upon it, the quickfilver fuddenly funk to 1260 degrees. The ball was then broken, and the mercury found frozen to a folid body, and there is no wonder in that, fince it was frozen to a folid body when the mercury had fallen to 500. But in this experiment, the quickfilver, which fill remained in the tube, was become folid, and appeared like a thread of filver wire, flexible every way, and faftened to the ball; the ball they forged into a flat circular form like a half crown, but at length it began to crack, and foon after became again fluid. During this experiment, the natural cold was 208. It is remarkable, that in an experiment made when the natural cold was 153 degrees, the quickfilver being taken out of a mixture in which it had fallen to 300, ftill continued to fall 100 degrees more, though after a certain time it liquified. This phænomenon the Ruffian philofophers have not accounted for; but it will not appear firange to thefe who know that intenfe cold is produced merely by evaporation, and that whatever is once wet, becomes colder as it is growing dry. Nothing more therefore is neceffary to produce the May we not therefore thus account for what the travellers just spoken of have advanced, concerning the mercury freezing to readily in their thermometers? * This article has probably undergone two trapllations, one from the Rus into French, and one from the French into English, and accordingly it contains fome obfcurities and inconfiftencies, which we fhall periments agree in this, that the quickfilver becomes folid, when it falls in the thermometer 500 deg. more or less;" (i. e.) they agree that there is a certain degree of cold which they do not at all afcertain, that will freeze quickfilver; for the words more or less leave this degree in abfolute uncertainty; and indeed we are told immediately afterwards, that these experiments "do not fo fufficiently agree as to deduce any thing certain about it:" It is, however deduced from the fudden freezing of the quickfilver in a glafs tube with artificial cold, " that the cold then produced ought to erceed 300 degrees." But we are told in the relation of another experiment," that the refult of a mixture was an augmentation of cold to 500 degrees, and that it muft then happen that the furprising degree obtained was neceflary to congeal mercury;" from all which it follows, that the degree of cold neceflary to correal mercury is 500 degrees more or less; that it must exceed 300 degrees, yet that at 300 degrees the furpating degree is obtained fufficient to congeal mercury. fhall beg leave to mention, in hopes of fecing them cleared up in the next volume of that curious and ufeful work from which this account is taken. We are told, that the quicksilver having fallen in the thermometer to 554 degrees," in taking the thermometer from the mixture, the quickfilver continued to fall in the open air, to the 552d degree" but if 552 is not more than 554, the quickfilver in this cafe did not fall, but rife. We are alfo told that the profeffor, who, by adding fnow and oil of vitriol to the mixture, caufed the mercury to fall from 554 to 1260 deg. is not fure whether the ball might not have received fome crack, and the qu ckfilver thereby might have had liberty to fall the lower;" but as the quickfilver is fuppofed to have been frozen to a folid body, not only in the bulb, but the tube, when it was down at 554, it is not eafy to conceive how a crack in the glafs could cause it to defcend 705 degrees more. The directions which are given to enable other philofophers to repeat thefe experiments are not expreffed fo clearly as could be wished: we are told it is necelary to ufe "faming spirit of nitre, or of fuch as is evaporated till the fumes become red, for common aqua fortis will not do." We are then directed to take "this fuming fpirit of nitre, cocled as much as poffible in liquifying now, and with it half fill a wine glas, the 10th of September, O throwing in as much fnow, at the We are told alfo in one place, that "the greatest part of the ex An Account of a curious phænomenon observed by Albé Nollet, in the year 1755. N 1755, about five o'clock in the evening, M. P'Abb. Nollet being on the road to Fonteinbleau, obferved, when he was near the albey de la Sauffaye, that the fun appeared very pale through fome light clouds, and that a fog rofe from the weft fide of the horizon to the zenith and beyond it. The wind blew blew very cold from the north, and foon after he perceived a kind of rainbow of about 120 degrees extent, the convex part of which was. towards the fun, and which feemed to be about the third part of a circle, of which the zenith would have been the center. This bow had all the colours of the iris, the convex part being red, and the concave blue; it faded by degrees, and in about a quarter of an hour wholly ditappeared. Soon after M. Nollet obferved in fome white clouds, at equal diftances to the right and left of the fun, two ftreaks, which feemed to be finall portions of a circle, of which the fun was the center, and of which the diameter feemed to be about forty degrees. Thefe fireaks confifted only of two colours, red and yellow; the part next the fun was red, and the oppofite part yellow: the fegment that was to the right of the fun difappeared fift, as that part of the fky first became clear; that on the left continued more than half an hour, that part of the fky continuing to be covered with white clouds., Thefe hænomena feem to confirm } the opinion of M. Mairan, printed in a memoir of the French academy of fciences, in the year 1721, that all pathelia, though very different in appearance, are the fame phanomena as the rainbow, and vary only by local circumfiances, which caule them to fade in different por tions at different times. An account of a burning well at Brosely in Shropshire; being, part of a letter from the reverend Mr. Mason, Woodwardian professor at Cambridge, and F. R. S. dated June 18, 1740. a T Brofely in 1711 was a well found, which burned with great violence, but it has been loft many years. The poor man in whofe land it was, miffing the profit he used to have by fhewing it, applied his utmoft endeavours to recover it; but all in vain till May. laft, when attending to a rumbling noife under the ground, like what` the former well made, though in a lower fituation, and about thirty yards nearer to the river, he happened to hit upon it again. That you may have fome notion what it is, I will lay before you fuch an account of it as the curfory view I had will permit. The well for four or five feet. deep is fix or feven feet wide; within that is another lefs hole of like depth dug in the clay, in the bottom whereof is placed a cylindric earthern veflel, of about four or five inches diameter at the mouth, having the bottom taken off, and the fides well fixed in the clay rammed clofe about it. Within the pot is a brown water, thick as puddle, continually forced up with a violent motion, beyond that of boiling water, and a rumbling hollow noife, riting or falling by fits five or fix inches; but there was no appearance of any vapour rifing; which perhaps might have been vifible, had not the fun fhone fo bright. Upon putting down a candle at the end of a flick, at about a quarter of a yard diflance, it took fire, darting and flathing in a violent manner, for about half a yard high, much but with greater agitation. The in the manner of fpirits in a lamp, man faid that a tea-kettle had been made to boil in about nine minutes time, and that he had left it børning forty-eight hours together with out any fenfible diminution. It was extinguished by putting a wet mop upon it, which must be kept there a fall time; otherwife it would not go out. Upon the removal of the mop there fucceeded a fulphureous fimoak lafting about a minute, and vet the water was very cold to the touch. The well lies about thirty yards 'from the Severn, which, in that place, and for fome miles both above and below, runs in a vale full 100 yards perpendicular below the level of the country on either fide, which inclines down to the vale at an angle of twenty or thirty degrees from the horizon, but fomewhat more or lefs in different places, according as the place is more or lefs rocky. The country confifts of rock, ftone, earth, and clay; and as the river, which is very rapid, washes away the foft and loofe parts, the next fucceffively flip into the channel, fo as by degrees and in time to affect the whole flope of the land; and as the inferior ftrata yield coal and iron ore, their fermentation may produce this vapour, and force it to afcend with violence through the chinks of the earth, and give the water the great motion it has. This might be obftructed in one place by the forementioned fubfiding of the floping bank, and might afterwards find vent in another, in like manner as happened at Scarborough a few years fince. A gentleman writes, June 16, 1761. THEN I was there eight WHE years ago, the cylinder had been taken up, or otherwife deftroyed; the well no longer appeared any thing elfe but a miry hole of clay. Other waters had been fuffered to mix with those of the burning fpring, which, though they confiderably diminished the efect, did not however wholly deftroy it; for upon the application of a piece of lighted paper, a ftream of clear flame fhot up from the well, which very much refembled that of a tea-kettle lamp fed by fpirits; but, as we could not keep out the other water, the flame prefently went out of itself. I forget now to what cause they told us this fhameful neglect was owing; whether to a conteft between two rival claimants to the property, or whether the curiofity of the circumjacent inhabitants, &c. being fully gratified, it no longer attracted a concourfe of vifitants fufficient to reward the attention of the Proprietor.It were to be wifhed, that fome of the gentlemen in that neighbourhood (which I have now left many years) would give us the prefent ftate of this wonderful phænomenon. |