to be drawn out very flender, and then order'd it to be fet upon quick STATICS. coals, where being kept for four hours, there appear'd for great part of the time fmoke to afcend from the zink, and get out at the unftopt apex; and I obferv'd that the upper part of the glass was lined with a darkish grey fublimate. The glafs being dexterously cut afunder, we took out, not only the filings of zink, fome of which were melted into little globules, but the flores too; yet weighing all these in the fame scales we had ufed before, we found above five grains wanting of an ounce. 27. Having carefully weigh'd out four ounces of good lead cut into little pieces, I put them into a small retort with a long neck, wherein was afterwards left only an orifice not much bigger than a pin's-head; this glass was kept over and upon the coals for above two hours, and then fuppofing the danger of the glafs's breaking to be over, we feal'd it up at the little orifice, and kept it on the coals for two hours longer; before we broke the glafs I perceiv'd the pieces of lead to have been melted into a lump, whose surface was dark and rugged, and part of the metal to have been turn'd into a dark-colour'd powder, or calx; all this being taken out of the retort, was weigh'd in the fame balance, whereon the lead appear'd to have gain'd by the operation fomewhat above 13 grains. 28. To fhew that metals are not the only bodies capable of receiving an increase of weight from the fire, we feal'd up two drams of little bits of good red coral hermetically in a thin bubble of glass, and kept them warily at feveral times over and upon kindled coals; and at length being taken out, found them of a very dark colour, and to have gain'd in weight about three half grains. 29. And having taken very strong fresh quick-lime, provided on purpofe for choice experiments, and exposed it, before the air had time to Make it, upon the cupel, to a ftrong fire, where it was kept for two hours, I found that it had increas'd in weight beyond my expectation; for being feasonably put into the balance, the lumps that weigh'd when exposed but two drams, amounted to two drams and 29 grains; hence it appears, that notwithstanding a body may for many hours, or even for fome days, be exposed to a very violent fire, yet it may be ftill capable of admitting and retaining fresh corpufcles; fo that tho' well made lime be usually obferv'd to be much lighter than the ftones whereof it is made, yet the lightnefs does not neceffarily prove, that because a burnt lime-ftone has loft much of its matter by the fire, it has therefore acquir'd no matter from the fire; but only infers, that it has loft far more than it has got; and this may give ground to fufpect, that in most of the foregoing trials, the accefs of the fiery particles was greater than the balance difcover'd; fince, for ought we know, many of the lefs fix'd particles of the expofed body might be driven away by the vehemence of the heat, and confequently the fiery corpufcles that faften'd themselves to the remaining matter might be numerous enough, not only to give the additional weight found by the fcales, but to make amends for all the fugitive particles that had been expell'd by the fire. And fince fo fix'd a body as quick-lime is capable of Eee 2 being STAгICS. a new small retort, with a long neck, by which it was held in the hand near a charcoal fire, that kept the metal in fufion; being now and then shaken for almost half an hour; in which time, it seem'd to have acquir'd, on the furface, fuch a dark colour, as argued a beginning calcination; and it both emitted fumes that played up and down, and alfo, afforded two or three drops of liquor, in the neck of the retort. The glafs was, at length, laid on quick-coals, where the metal continued above a quarter of an hour longer in fufion; but, befote the time was come, that I intended, to fuffer it to cool, in order to its removal, it fuddenly broke, into a great multitude of pieces, and with a noife, like the report of a gun. In the neck we found fome drops of a yellowish liquor, which had an odious and peculiar tafte; its fmell alfo, was very fetid, not unlike the distilled oil of fish. 24. Some tin, which had been before, partly calcined in a glafs, being melted again in a crucible, we weigh'd out juft eight ounces, and these we put into a bolt head of white glafs, with a neck above twenty incheslong, which being hermetically fealed, after the glafs had been a while kept over the fire left it fhould break by the rarif.ction of the air, the metal was kept in fufion for an hour and a quarter. Being unwilling to venture the glass any longer, it was taken from the fire, and when grown cold, the fealed end was broken off; but before I could have the bottom cut out, I obferved, that the upper furface of the metal was very darkly colour'd, and very irregularly rough; and the lower part had, between the bottom, and the under fide of the lump, a pretty deal of loose dark-colour'd calx, tho' the neighbouring furface, and fome places of the lump itself, look'd, by candle-light, of a golden colour. The lump, and calx together, were weigh'd in the fame fcales carefully, when we found the weight to have increased above twenty-three grains; tho' all the calx we could easily separate, being weigh'd by itself, amounted not to eighty grains. 25. Two ounces of filings of tin, were carefully weigh'd, and put into a little retort, whofe neck was afterwards drawn flender to a very small apex; then the glafs was placed on kindled coals, which drove out fumes at the small orifice of the neck, for a pretty while. Afterwards, the glafs, being fealed up at the apex, was kept in the fire for above two hours; and then being taken off, was broken at the fame apex: whereupon I heard the external air rush in, because, when the retort was fealed, the air, within it, was highly rarified. Then the body of the glafs being broken, the tin was taken out, confifting of a lump, about which there appear'd fome grey calx, and fome very small globules, which feem'd to have been filings melted into that form. The whole weigh'd two ounces, and twelve grains. In the neck of the retort, where it was join'd to the body, there appear'd a yellowish, and clammy substance, thinly spread, which fmelt almoft like the fetid oil of tartar. 26. We took one ounce of the filings of zink, carefully weighed; and having, as carefully, put them into a round bolt-glafs, we caufed the neck to be drawn out very flender, and then order'd it to be fet upon quick STATICS. coals, where being kept for four hours, there appear'd for great part of the time smoke to afcend from the zink, and get out at the unftopt apex; and I obferv'd that the upper part of the glafs was lined with a darkish grey fublimate. The glafs being dexterously cut afunder, we took out, not only the filings of zink, fome of which were melted into little globules, but the flores too; yet weighing all these in the same scales we had ufed before, we found above five grains wanting of an ounce. 27. Having carefully weigh'd out four ounces of good lead cut into little pieces, I put them into a fmall retort with a long neck, wherein was afterwards left only an orifice not much bigger than a pin's-head; this glass was kept over and upon the coals for above two hours, and then fuppofing the danger of the glass's breaking to be over, we feal'd it up at the little orifice, and kept it on the coals for two hours longer; before we broke the glafs I perceiv'd the pieces of lead to have been melted into a lump, whofe furface was dark and rugged, and part of the metal to have been turn'd into a dark-colour'd powder, or calx; all this being taken out of the retort, was weigh'd in the fame balance, whereon the lead appear'd to have gain'd by the operation fomewhat above 13 grains. 28. To fhew that metals are not the only bodies capable of receiving an increase of weight from the fire, we feal'd up two drams of little bits of good red coral hermetically in a thin bubble of glafs, and kept them warily at several times over and upon kindled coals; and at length being taken out, found them of a very dark colour, and to have gain'd in weight about three half grains. 29. And having taken very strong fresh quick-lime, provided on purpofe for choice experiments, and expofed it, before the air had time to Make it, upon the cupel, to a strong fire, where it was kept for two hours, I found that it had increas'd in weight beyond my expectation; for being seasonably put into the balance, the lumps that weigh'd when exposed but two drams, amounted to two drams and 29 grains; hence it appears, that notwithstanding a body may for many hours, or even for fome days, be exposed to a very violent fire, yet it may be ftill capable of admitting and retaining fresh corpufcles; fo that tho' well made lime be usually obferv'd to be much lighter than the ftones whereof it is made, yet the lightnefs does not neceffarily prove, that because a burnt lime-ftone has loft much of its matter by the fire, it has therefore acquir'd no matter from the fire; but only infers, that it has loft far more than it has got; and this may give ground to fufpect, that in most of the foregoing trials, the accefs of the fiery particles was greater than the balance difcover'd; fince, for ought we know, many of the less fix'd particles of the exposed body might be driven away by the vehemence of the heat, and confequently the fiery corpufcles that fasten'd themselves to the remaining matter might be numerous enough, not only to give the additional weight found by the scales, but to make amends for all the fugitive particles that had been expell'd by the fire. And fince fo fix'd a body as quick-lime is capable of Eee 2 being STATICS. being wrought upon by the fiery effluvia, fo that they come to be as it were incorporated with it, perhaps in other calcin'd or incinerated bodies, the remaining calces or afhes may retain more than the bare impreffion of the fire. By this experiment, and those made in seal'd retorts, which shew, that what is afforded by fire, may in a corporeal way invade, adhere, and add weight even to fix'd and ponderous bodies, there is a large field opened for the fpeculative to apply the difcovery to many phenomena of nature and chymistry. Glass pervious to ponderous parts of flame. T SECT. II. O obviate fome fcruples that might be entertain'd upon this circumstance of our experiments, that the glaffes employ'd about them were not exposed to the action of mere flame, but held upon charcoal, I attempted to make them fucceed with a body fo thin, and difengag'd from grofs matter, as mere flame is allow'd to be. 1. Suppofing then that good common fulphur, by reafon of its great inflammability, and the vehemency and penetrancy of its flame, would be a very fit fewel for my purpose, I provided a small double veffel, fo contriv'd, that the one part fhould contain as many coals as were neceffary to keep the fulphur melted; and the other, which was much smaller, and shaped like a pan, fhould contain the brimstone requifite for our trial; and that these two should be, with a convenient lute, fo join'd to one another, that all being clofed at the top, except the orifice of the little pan, the fire and smoke of the coals having their vent another way, no fire fhould come at the retort to be employ'd, but the flame of the burning brimstone; then two ounces of filings of tin being carefully weigh'd out, and put into a glafs retort provided for fuch trials, and made fit to be eafily feal'd up at the neck, the fulphur, which ought to be of the purer fort, was kindled, and the glass by degrees expofed to it, where that continu'd near two hours before the metal melted; after which the retort was there kept on near an hour and a half more, with the metal melted in it; then perceiving a pretty deal of darkish calx at the bottom, and partly too upon the furface of the far greater portion of the metal, which now lay in one lump, the part of the retort which had been feal'd being broken off, we first took out the calx, and next the lump, and putting them into the fcales they had been formerly weigh'd in, we found them to have acquired four grains and a half. The experiment was afterwards repeated with the fame quantity of filings of the fame metal, and at the end of the operation, which in all lafted fomewhat above three hours, having broken off the feal'd neck of the retort, we found that a large proportion of dark-colour'd calx had been produc'd; and this being weigh'd with the uncalcin'd part of the metal, the two ounces we firft put in appear'd to have acquired no less than eleven and a half. Such fuperftructures may, poffibly, in time, be built on this and the STATICS. Like experiments, that I fhall here obviate even a fcruple, which appears too fceptical. But, confidering that tho' it were very improbable, yet poffible, that the increase of weight acquired by bodies expofed in glafs veffels to the fire, might proceed not from the corpufcles of fire, but from the particles of glafs itfelf, loofened by the power of fo intenfe an heat, and forcibly driven into the inclofed body; I took two glaffes, the one shaped into a little retort, and having weigh'd them, kept them. for a confiderable time upon kindled coals, and then weigh'd them again, I could gather little of certainty from the experiment; (the retort at one time feeming to have acquired above half a grain in the fire) only that there was no likelihood at all, fo confiderable an increase of weight, as we several times obtained in clofed veffels, fhould proceed from the glafs itself, and not from the fire. 2. We carefully weighed out an ounce of the filings of block-tin, and put them into a glass retort, whofe neck was afterwards drawn out flender; we alfo provided such a convenient metalline lamp, that the flame of the fpirit burnt in it, might not melt or crack the glafs. This lamp, tho' furnish'd with a cotton wieck, afforded no foot; because, as long as it was well fupplied with liquor, it remain'd unburnt. These things being in readiness, the retort was warily approached to the flame, and the metal thereby in a fhort time melted. After which, the glafs being kept expofed to the fame flame, for near two hours, the feal'd apex of the retort was broken off; when there appear'd to have been produced a confiderable quantity of calx, that lay loofe about the remaining part of the tin, which upon its growing cold was harden'd into a lump. This and the calx being taken out of the retort, with care, that no little fragment of glass should impofe upon us, it was weigh'd in the fame fcales as formerly, and found to have gain'd 4 grains, befides the duft that ftuck to the infide of the retort; of which we reckon'd enough to make about half a grain more: fo that of fuch a fine and pure flame as of this totally ardent spirit, enough to amount to the five grains was arrested, and, in good measure, fixed, by its operation on the tin. 23. For confirmation of the laft experiment, wherein we had employed the inflammable fpirit of fugar, we made the like with highly rectified fpirit of wine; only fubftituting an ounce of lead inftead of one of tin The event was, that after the metal had been, for above two hours, kept in the flame, the feal'd neck of the retort being broken off, the external air rufh'd in with noife; and we found above feven fcruples of lead turned into a greyish calx; which, together with the rest of the metal, being weigh'd again, fix grains appear'd to be gain'd by the operation. These feven fcruples of calx being weighed in air and water, I found, that tho' the abfolute gravity of the metal had been increased by the particles of flame which ftuck faft to it; yet this aggregate of lead, and extinguished flame, had loft much of its fpecific gravity: for lead is to water of the fame bulk, as about 11 to 1; whilft this fubtile calx of lead was to water of the fame bulk, but as to 9 to 1. Now |