G, the fpring depreffing the valve. H, a gnomon affixed to the globe AA, and making faft the fpring G. DD, a plug exactly fitted to the tube. EEE, another plug fitted alfo to the tube BB, with an iron wire, reaching almoft to the valve F. R, the protuberance of the tube CC, fomewhat hollowed above, to receive the end of the iron LL. LL, a crooked iron, moveable about the extremity in R, fo that it ferves as a lever to lift up the plug EEE. OPO, a crooked iron, faftned in M, that the thumb refting in the angle P, the reft of the fingers may attract the lever L, and fo force the plug EEE, upwards. But the curvature is defign'd, that the one end O, might be applied to the shoulder, in aiming at a mark. TT a rectangular piece of iron, compaffing the lever LL and the iron OPO, to keep the lever in its pofture; for, otherwife, the plug EEE, would be thruft far out, whilft the air is intruded into the globe AA. II, an elliptic hole, in the upper part of the globe, very well fhut with a valve, opening inwardly, to give liberty of infpection, and of amending what is amifs; for the valve may be drawn through the hole, by reafon of its elliptic figure. SS, a metalline plate tranfverfly placed above the hole II, and perforated to tranfmit the fcrew V, by help whereof the valve, fhutting the hole II, is fuftained, and applied clofely to it. Q, a hole in the lower part of the tube CC, by which the air enters into the tube, whilft the plug D, is brought to the lowest part thereof. The air is forced into this engine, by fetting the foot upon the crooked end of the plug DD, that it may not be removed from the ground, and lifting the engine upward, till the upper part of the plug comes below the hole Q; and then the air entring through the hole, wholly fills 'the tube CC. Then, by forcibly depreffing the engine, the air, contained in the tube CC, opens the valve F, and is thruft into the globe AA; whence it cannot return, because the valve prefently ftops the paffage: and thus, by repeated ftrokes, we may condense the air in the globe, till the force of its fpring cannot be overcome by our ftrength. If we would difcharge the air fo condenfed, the plug DD, is wholly to be drawn out, and a bullet to be put into the bottom of the tube CC: then, by means of the lever LLL, the plug EEE, is to be impell'd upward, as we faid before; when, the extremity of the iron-wire, opens the valve B, and the air breaking out therefrom, expels the bullet through the tube CC, with great violence. But before the plug DD, is again put into the tube CC, for the compreffion of the air, about half an ounce of water is to be pour'd into the tube. For, by this means, no air at all can efcape out by the plug; and, moreover, that water exactly filling the upper part of the tube CC, the Cccc2 whole PNEUMATICS. PNEUMATICS whole compreffed air will be intruded within the cavity AA; and fo the condenfation be perfected much fooner, than if, at every turn, part of the comprefs'd air remain'd below the valve F. An engine wherewith to diftil in vacuo. Fig. 81. This engine has feveral advantages above the common wind-guns. 1. Be- We, alfo, contrived an engine, which should diftil in vacuo, thus. 4. But BB, a diaphragm of tin, whofe edges are fo polifh'd on both fides, that they exquifitely agree and fuit with the edges of the veffels AA, DD, which are alfo polifhed, and fo keep out the external air. CC, a tube faften'd to a hole in the middle of the diaphragm BB. FF, a tube reaching from the ftop-cock EE, to the hole made for fu ction in the pneumatic engine. GG, a metalline veffel, including the junctures of the veffels with the diaphragm, and alfo the ftop-cock, that being filled with water, it may keep all fafe from the external air. This is to be folder'd to the vessel AA. To ufe this engine, we take away the diaphragm BB, and put the ingredients into the veffel AA, and fet it in a convenient place, till it is to be evacuated; then putting on the diaphragm BB, and the veffel DD, we apply all to the pneumatic engine, and by means of the tube FF, the air is pumped out of the veffels, the veffel GG being yet firft filled with water. Then the ftop-cock is fhut; and taking away the tube FF, we may place the evacuated engine on the fire, when the vapours, afcending through the tube CC, are condenfed in the upper veffel, and fo we have a liquor diftilled in vacuo. The quantity of the generated air, is known by the mercurial gage H; but that must be kept in the top of the receiver, left the mercury exhale, by reafon of the heat. Round pieces of paper, perforated in the middle, are to be laid over the orifices of the veffels AA, DD, that they may be the better joined with the diaphragm; the commiffures of the tube FF, with the stop-cock, and pneumatic engine, are to be fortified with cement; and the ftop-cock EE, E is fo to be difpofed with the veffel GG, that part of the key may be promi-PNEUMATICS, nent, without the veffel, thro' the hole, to be conveniently turned; nevertheless, the stop-cock, with the diaphragm, may be taken out of the vesfel GG, whilft the vefiel AA, is to be filled with the defigned matter. And that is very eafily done, because the key confifts of two parts, one of which M, is turned in the ftop-cock itself, by means of a certain chink, which receives the fmall protuberance of the other part OO, that exactly fills the fmall pipe NN, faftned to the veffel GG; and being prominent outwardly, may eafily be turned in it, and communicate its motions to the other part M: but it is drawn outward, whilft the diaphragm BB, is to be taken out of the veffel GG. Fig. 82. fhews another inftrument, differing from the former, in that it, almoft, wholly confifts of glass, and affords a longer paffage for the va pours. BB, is not a diaphragm, but a fmall tube, polifhed at both ends, that it may exquifitely fuit with the orifices of the veffels A, and D. AA, DD, are two glass veffels, whofe orifices are applied to the tube BB; whence the vapours are easily tranfmitted from the one to the other. EE,FF,GG, and I, have the fame ufe as in the former figure; and the whole inftrument is to be evacuated after the fame manner, and placed upon the fire; except that here the veffel AA, as being made of glass, must not be put on an open fire, but fet in balneo Maria, or on fand; and the vapours will be condenfed in the vessel DD. (1.) July 11. 1676. I included a little piece of bread, very moift, and little kneaded, with a mercurial gage, in vacuo. a Several ways to forward the preduction of air and firft, air produced from July 12. In fix hours time, no air was produced yesterday; but this night, a little broke into the receiver, and fuftain'd three inches of mercu-bread. ry; for I had neglected to fortify the cover with turpentine. Towards the evening, I found the mercury higher by about an inch; and am very certain, that nothing had entred from without. July 13. This night, alfo, the mercury afcended higher; but my gage was not exact enough to difcover how many degrees. July 26. The bread disjoined its receiver from the cover, by the force the air produced, and the fmell of it was acid. Hence it follows, that water is a fit menftruum to draw air out of bread. (2.) July 11.I tried to extract air from bread, by the help of a burningglafs, wherewith I burnt bread in vacuo, and found it generate much air, which, ever and anon, broke out, as by fulmination; whence it feems probable, that air is contained in bread, but fo clofely compacted therein, that no eafy operation can give it vent; but that if any thing could diffolve and loofe that knot, it may then produce great effects. (3) Sept. 22. I took eight ounces of dry'd grapes, and, with feven oun- Frows grapes. ces of water, included them in a receiver, able to hold twenty-two ounces of water. The grapes were bruised. Sept. 23. The receiver lay buried under the water all this night, yet the mercury afcended two whole inches. Sept. PNEUMATICS Sept. 30. In feven days time the mercury rofe to the height of thirteen From raifins. From plumbs. From grapes. inches. Octob. 5. In five days more, the mercury afcended twelve inches, and was now twenty-five inches high. Octob. 18. The mercury continued not to afcend with the fame swiftnefs, and the air began to pafs out of the receiver; but not before this day; yet thefe grapes produced much more air, than those which I included without water. (4) July 12. I included ten ounces of raifins of the fun, bruised in vacuo, with a fufficient quantity of water, to promote fermentation. July 14. In two days they had produced ten inches of air. About evening, the mercury was fifteen inches high: the fifteenth day the mercury had almoft reached to its accuftomed height. July 16. In the morning, I found the receiver fever'd from its cover; and the air breaking out thro' the water, in which it was plunged, I included the fame raifins again in vacuo. July 18. This day, in the morning, I found the air again breaking out. July 19. I fhut up the fame raifins in the fame empty receiver. July 21. This day I found the receiver full, and the air breaking out of it. I again fhut up the fame raifins in the fame exhausted receiver. July 23. Yefterday, about noon, I found the whole receiver almoft full. of air; and this day, in the morning, perceiv'd it to pafs out very often. It appears, then, that grapes without water, can generate but little air; whence it is manifeft, that water is a fit medium to draw air out of them: "Tis alfo evident that the production of air is not begun prefently upon the affufion of water, but proceeds with greater fwiftnefs, after the parts of the water, in five or fix days time, have more deeply funk into, and pervaded the grapes. (5.) Aug. 13. 1677. I included pears in two exhausted receivers, and plumbs in another. Aug. 16. In three days time, all my receivers were filled with air, newly generated; and one of them, which included the pears, because I had left it expofed to the fun, was, in the space of 24 hours, feparated from its cover whence we may conjecture, that the production of air is very much promoted by the heat of the fun. (6.) Octob. 16. 1677. I took two ounces of grapes bruised, and fecured them from the air, in an exhaufted receiver, capable of containing twenty ounces of water. Octob. 17. The mercury rofe higher about one half-inch. Octob. 18. These laft twenty-four hours, the mercury ran up about another half-inch. Octob. 20. The height of the mercury was two inches. On the twenty-fecond, it was almoft four. And, on the twenty-feventh it was almost fix inches. Jan. Jan. 2. 1678. The mercury, yet, afcended not to the height of ten PNEUMATICS inches. Octob. 16. 1677. I put three ounces of bruis'd grapes, with half an ounce of fpirit of wine, into a receiver, able to hold thirty ounces of water; and then I exhaufted the air. Octob. 17. The mercury afcended but a very little. Octob. 18. The mercury came not up to the height of one quarter of an inch. Octob. 20. The mercurial gage was out of order. Jan. 2. 1678. I, this, day found my receiver fill'd with air; and, alfo, when part of the liquor was pour'd out, fome bubbles were form'd in the turpentine, about the orifice, and broke outwardly. From this experiment, made in two receivers together, it seems to follow, that fpirit of wine much advances the production of air in vacuo; · tho, in common air, it wholly hinders it. (7.) July 19. 1678. I put muft, expreffed from grapes bruis'd, and kept From muß. for ten months in a veffel, ftopp'd with a fcrew, into the fame receiver, being alfo ftopp'd with a fcrew. July 21. The mercury had not afcended at all. 23d. The height of it was three. 24th. The height was five. 25th. In the morning it was an hundred and four. Towards the evening, the height was an hundred and thirty-feven; and the muft got out. 26th. The muft was almost all got out of the receiver; and altho' the air now poffefs'd double the space it did yesterday, yet it kept up the mercury to the fame height. 27th. About half of the remaining muft broke out this night, because I had omitted to set the screw, left the receiver should be broken. From this experiment it follows, that grapes, kept for fo long a time,, rather acquire, than lofe a fermentative virtue. (8.) Jan. 30. I put two quantities of apples, boil'd the day before, into From apples two receivers, ftopp'd with fcrews; with one of them I mix'd a third part of fugar, the other had no fugar at all. These receivers were quite full. Jan. 31. I included raw apples, bruis'd, in three receivers; in one of thenr I mix'd a third part of fugar; the fecond was without fugar, and fo was the third; but it differ'd herein from the fecond, that it was fix times as. big: for, by this means, we may know, whether the capacity of the vesfel, or the mixing of fugar, or the crudity of the fruit, can promote, or retard the production of air. Febr. 10. In that receiver, only, which contain'd the raw apples, with fugar, fome air was produc'd. Febr. 14. The raw apples, with fugar, had impell'd the mercury up to thirty inches; thofe that were boiled with fugar, to two only; in the other receivers no air was produced.. Febr. |