I included another cone of the fame fort in a much greater receiver, but PNEUMATICS did not comprefs the air therein: the cone, fired by the fame burning-glass, was not taken out, till all the fumes abated and fell down; yet, much lefs of this cone was burnt, than of the former. (77) May 19. I weigh'd a perfumed cone exactly, and then firmly included it in a receiver with common air, and kindled it by means of a burning-glafs; when the fumes were condenfed, I took the cone out of the receiver, and found, it had loft of its weight, almoft one grain. Afterwards, the fame cone, obferving the fame circumftances, was again included and kindled; but first I had intruded as much air into its receiver as fuftain'd ninety inches of mercury; and, by means of a pair of fcales, found the lofs of weight, now, to be four times more than before. Hence it feems to follow, that the confumption of matter by fire is greater in proportion to the quantity of air contain'd in the receiver. (78.) May. 17. 1677. I included a perfumed cone in a receiver firmly ftopp'd by the help of a fcrew; and the air compreffed to fuftain fixty inches of mercury above its ufual height, I fir'd it with a burning-glafs; the cone being afterwards taken out, had loft three grains and an half in weight. I repeated the fame experiment in air, fo compreffed, that the mercury reached one hundred and twenty inches higher than ufual; then the cone was feven grains and three quarters lighter; and fo, tho' the quantity of the air was not double, yet the confumption of the matter by fire, was more than twice as much as in the former experiment. May 17. I made the fame experiment in air, compreffed to fuftain ninety-feven inches of mercury; and, then, the lofs of weight feem'd to be fix grains. Hereby we are taught, that the matter is the more confumed by fire, as the compreffure of the air in the receiver is the greater; or rather, that the confumption is made in a proportion greater than that of the compreffure. May 18. 1677. I intruded a perfumed cone, as before, in a receiver feven times larger than that used in the former experiments; and crowded no air at all into it. The cone, kindled there, loft three grains and a quarter of its weight; whereas, in the fame quantity of air, if reduced to a fifth part of its fpace, it would have loft ten grains. Hence it feems to follow, that the fame quantity of air, reduced to lefs than its accuftom'd space, caufeth a greater confumption, than in its na tural ftate. (79.) May 19. 1677. I repeated the laft experiment, in the fame receiver, clofely ftopp'd with a fcrew, that nothing might get out or in. The cone loft but one grain and a quarter of its weight; whence I fufpect, that it was not well kindled. May 21. I made the fame experiment, in the fame manner; and this day the cone was lighter by four grains; whence I more certainly collected, that it was not well fet on fire in the preceding experiment. Hhhh 2 : May PNEUMATICS. May 23. I repeated the fame experiment twice, but fufpect, that the cone was not well kindled; fince, at one time, it loft, only three quarters, and at another, one grain of its weight. May 24. I made the fame experiment again; and this day also the lofs di weight was found only one grain and a quarter. Then I open'd the receiver, and having wiped and cleans'd away the foot, repeated the experiment; when the cone took fire very well; for the lofs of its weight amounted to fix grains and an half. I tried the fame experiment again, in an uncleans'd receiver, and the cone loft only three grains. May 25. I made the fame experiment in a receiver well wash'd, and the cone was lighter by fix grains and an half. I made the fame experiment, in the like manner, in a well cleans'd receiver, and the cone loft feven grains and an half. I made the fame experiment again, in an unwafh'd receiver, and then I could not fufficiently kindle the cone. May 26. I made the fame experiment in an unwash'd receiver, about the middle of the day; the fun being clear, and bright; and remov'd not the burning-glafs for a long time, fo that it took fire very well, and became eight grains lighter. Hence it is manifeft, that the quantity of a cone to be confumed in the fame quantity of air is not fix'd and certain, but fometimes greater, fometimes lefs, as the cone fhall be more or lefs kindled. Befides, the imperfect mixture of the matter may caufe fome difference; yet it feems certian, that fire is more eafily kindled in compreffed air, than in common; and the confumption will be the greater in a certain quantity of air, if that air be reduc'd into a narrower fpace, than if it poffefs'd no more than ufual. (80.) May 22. I put a perfumed cone into a receiver made for compreffing the air; and intruding the air till the mercury refted thirty inches above its ufual height, I kindled the cone, and found its weight to be abated one grain and three quaters. May 23. I made the fame experiment again, after the fame manner, and with the fame fuccefs. I repeated the fame experiment, but the cone did not kindle well. Whence we have a confirmation, that fire is more easily kindled in air much compreffed, than in common air, or that which is but a little condensed. I repeated the fame experiment, and after I had remov'd the burningglafs, whilft I was intent to fee, whether the cone would proceed to be confumed, the receiver brake into an hundred pieces, fome of which, ftruck my head and wounded it: which I mention, that no man may be confident his glafs will not break, whilft he is about fuch experiments, becaufe he has found, that at other times it refifted a greater preffure. For this very glafs, had contain'd air four times more comprefs'd. It had also refifted air, fuftaining one hundred and ninety-eight inches of mercury above its wonted height; yet, now it was broken by a preffure, more than fix times lefs; and, therefore, while a man looks into fuch receivers, his PNEUMATICS. head fhould be guarded. (81.) June 4. 1676. I burnt paper, befmeared with fulphur in vacuo, Fire made afe and found, that it prodced fome air; which was not at all diminish'd for of to produce air,. and first paper, two days. befprinkled with This air must be afcribed to the paper, for none is produc'd out of ful-fulphur burnt in phur alone. (82.) June 15. I burnt harts-horn in vacuo, and found, that the fumes, Harts-horn iffuing therefrom, contain'd fome air. June 17. On these two laft days, I repeated the fame experiment, and always obferv'd, that air produced from harts-horn, was foon, in part, deftroy'd; but that, which preferved its elafticity for an hour after the burning-glafs was remov'd, feem'd, afterwards, not to lose it at all. June 19. I took the harts-horn out of the receiver, and found no volatile. falt, but only a fetid oil to be produc'd therefrom. burnt in vacuo.. vacuo. (83) June 21. I burnt amber in vacuo, and, at firft, could not find that the Amber burnt in fumes afcended above the height of one inch; yet, in a receiver full of air, they would be carried up to the top, and from thence return downwards; yet, afterwards, even in the vacuum itself, the fumes reached almoft to the top of the receiver, but the mercury varied not at all in its gage. June 22. This night, a great deal of that water, in which I had immerfed the receiver, found a paffage into it, tho' the cover was fo well fitted to the aperture, that I never perceiv'd any water to get in betwixt them, before. Hence a fufpicion arofe, that fome volatile falt had, probably attracted the aqueous parts, by reafon of the congruity betwixt them. July 8. I ftill kept the receiver immerged in water, but no more water entered in; as if, the falts being washed away, the external water, deftitute: of affiftance, could no longer infinuate. (84) Jan. 18. 1677. I put two drams of camphire into an exhaufted re- Camphire fubliceiver ; and the juncture of the cover, with the receiver, being fortified a-med in vacuo.. gainst external air, I put the camphire on a digefting furnace. Jan. 19. The camphire fublimed into flowers, but no air was produced. (85.) May 24. 1676. I included Sulphur vivum in an exhaufted receiver, Sulphur vivum and melted it by the help of a burning-glafs; but found, that the fumes, fused in vacuo., produced therefrom, contain'd no air, because the mercury afcended to the aperture of its gage, as is ufual, while the receiver is evacuating; yet, when that was cool'd, the mercury return'd to its former height: and, therefore, that change was, probably, owing to the air included in the feal'd leg of the gage, being rarified, and driving the mercury into the other part. (86) July 19. Having included. pafte, nine days ago, in vacuo, and per- Pafte expos'd to ceiving that it now contain'd no more air, I endeavour'd to fire it with the rays of a burning-glass in a burning-glafs. The fubfiding fumes had tinged the fuperficies of the vacuo. pafte, of a curious yellow; and, I conjectur'd, that fome air was produced, because the receiver, which, before, was clofely join'd to its cover, might now, with eafe, be pluck'd therefrom. PNEUMATICS The production of air from grapes in vacuo. From figs. From pears and apricocks. (87.) September 9. 1676. I exhaufted the air out of a receiver, half full of dried grapes, and fortified it against the external air. Sept. 10. In twenty-four hours time, the height of the mercury was. 27. The afcent was. The height three inches. October 11. The height of the mercury was now about fix inches. September 9. 1676. I put dried figs into a receiver, and fill'd about half of it with them; then I extracted the air, till the mercury rested at the height of three inches. Sept. 10. No air was produced. Sept. 17. Perceiving no air to iffue out of the figs, I open'd the receiver. Hence we learn, that dried fruits, put into an exhausted receiver, produce very little air with regularity. (88.) Auguft 5. 1676. I included pears and apricocks in vacuo. Aug. 6. In eighteen hours time, the mercury rofe two inches; in ten hours more, it reach'd to three. Aug. 7.2 Aug. 10 II 12 ?} The height of it was 9. In fourteen hours fpace, the mercury mounted three quarters. 19 20 625 29 31 21 >The height of it was< 32 ΙΟ 12 13 >The height of it was 144 16 22 14 Aug. 29. The height of the mercury was forty-one. Sept. 1. The height of it was forty-two and a half. 4. The height of it was forty-four. 7. The three last days, being hotter than the foregoing, the ascent of the mercury was two and a quarter; its height, forty-fix and a quarter. Sept. 10. The height of the mercury was forty-feven and a half. 13. The mercury was depreffed; its height only forty-four inches. 23. The mercury, by degrees, mounted again to forty-eight inches. 27. The height of the mercury was fifty and a half. Nov. 5. The mercury afcended, gradually, to fifty-two and a half. Nov. 28. The apricocks were reduced to water; the skin being fever'd from the pulp, yet no more air produced. Jan. 10. 1677. Whilft it froze very hard, the mercury rofe to fiftyfeven inches; but, when it thaw'd, it funk to twenty-three. Whether the strength of the froft open'd fome way for the air to get out, I know not. March March 3. The mercury could afcend no higher, because the air was got PNEUMATICS. out. This day I found the receiver tumbled on the ground; and the apricocks, when the froft broke, were putrefied, and had loft their colour. Hence it feems to follow, that apricocks produce air almoft as easily in their wonted preffure, as in vacuo. (89.) June 22. 1676. I put four cherries into two exhaufted receivers, From cherries. and, proceeded with both alike, except that in the one, the cherries were whole, in the other, cut afunder; in two hours, the whole cherries had impell'd the mercury into the gage, to the height of ten lines, and the cut ones to about twenty. June 21. In twenty-four hours, the mercury, in the receiver containing the whole cherries, rofe to the height of three inches; but, in the other, the gage was fpoil'd. June 26. The whole cherries had not yet produced fo much air, as to fuftain fifteen inches of mercury; but the cut cherries had wholly fill'd their receiver with air. July 9. The receiver of the whole cherries was removed from its cover; I eat one of them, which tafted pleafant enough. I included the reft again in vacuo; many of them were broke, and, in one hour's time, they impell'd the mercury to the height of about two inches. July 10. During thefe last twenty-four hours, the mercury afcended not: whether the gage was damaged, I am not certain. July 15. I found the cover fever'd from the receiver; whence it was clear, that the gage was hurt. Hence it appears, that fome cut fruit, fooner produce their air, than what is whole. (90.) June 9. 1676. I put fome cherries, that were not acid, into an exhaufted receiver; and, within an hour, found as much air produced from them, as fuftain'd a quarter of an inch of mercury. June 10. In eighteen hours, the mercury rofe to eleven inches. June 11. The fruits produced lefs air, gradually; fo that, this day, towards the evening, the mercury came not up to fifteen inches. June 12. The mercury was a little higher than fifteen inches. 13. The height of the mercury was twenty-two inches. 16. The mercury, yet, came not up to thirty. 18. Perceiving no more air to be produced, I open'd the receiver. Such a fmall production of air feems very remarkable, because I had found fruit, of the fame kind, in France, to fill their receivers in two days time. Probably, fruits of the fame kind, in feveral countries, differ much amongst themselves. (91) June 12. 1676. I put cabbages, cut in pieces, into an exhausted From cabbages receiver, with a mercurial gage; and, in an hour's time, the mercury afcended one line. June 13. The mercury was now come almoft to the height of ten inches. 17. It was come almoft to the top of its gage; and, the receiver being open'd, I found the cabbages little alter'd. June |