PNEUMATICS.

receiver.

Feb. 21. In the first receiver, the height of the mercury was four inches and a half; in the third, ten; but in the fecond, there was no afcent at all.

Feb. 25. The height of the mercury in the firft receiver was fix; in the third, nineteen; in the fecond half an inch.

Feb. 26. This night, there was no afcent of the mercury in any of the receivers. I open'd the third, and the fiefh, after boiling, was very good.

By the former experiment, fpices feem to hinder the production of air; but the prefent experiment proves the contrary. Whence this contrariety fhould proceed, I know not; unless, perhaps, because, I had left a space large enough for the air in thefe receivers; but in the former experiment, fill'd all as exactly as I could with flesh.

March 9. The height of the mercury, in the firft receiver, was eight inches; in the fecond, none.

March 12. The height of the mercury in the firft receiver was twelve ; in the fecond, one.

April 3. The height of the mercury in the first receiver was eleven; but in the fecond it exceeded not, one. I open'd the receiver, and boiling the flefh, found it very tender, and of an excellent tafte.

Hence the faltnefs of water, included with flesh, seems to hinder the production of air; but there being fo fmall a quantity of water, compar'd with the quantity of flefh, I rather incline to think, that lefs air was produced in the fecond receiver, because it was more exactly fill'd. And, indeed, fresh water being ufed inftead of falt, has the fame effect; but the chief art to preferve flesh without falt, confifts in excluding all air from it, and making a great compreffure in the receiver.

Thefe experiments, about the prefervation of aliment, may be very useful in tranfporting fruits, venifon, &c. from remote places, and towards affording better nourishment to mariners.

Boiling and di- (189.) Decemb. 12. 1678. I put two ounces, and fix drams of beef into tillation practi- an exhausted receiver, able to hold twenty-two ounces of water; then I Jed in vacuo; and first, beef boiled left it in boiling water for three hours; which done, I expos'd it to the air, in an exhausted to cool for a whole night: afterwards, ufing my pneumatic engine, I perceiv'd, that the air, formed in the receiver, could fcarce fuftain three inches of mercury: whence flesh in boiling, cannot form air enough to make an entire preffure in a receiver, capable of holding a double weight of water: that is, if you include one pound of flesh in an exhaufted receiver, able to hold two pounds of water, it will not generate air enough to remove the cover from the receiver, unless heat greatly contribute to produce the effect: but, our flesh, I confefs, was not boil'd enough.

(190.) Decemb. 23. I inclos'd three ounces of raw beef in a receiver able to hold thirty-two ounces of water; and in boiling, after it had been long on the fire, the cover was forc'd from the receiver, and fo fuffer'd the vapours to pafs out: but being prefently fhut again, and the fire remov'd, the receiver foon loft its internal preffure; fo that being re-plac'd on the fire, it was a long time before it could force away the cover a fecond time. I tried

this again, and again; and unless the receiver had been expo s'd to a very ftrong fire, the cover would never have been remov'd; but if the fire burns well, fweet exhalations continually pafs out.

Decemb. 24. The receiver having been cool'd, during the whole night, was, this day, by the ufe of the pneumatic engine, almoft wholly evacuated. Whence we feem to have a confirmation, that the divulfion of the cover is not made by that air, which can keep the form of air, but from the fteams exhaling from the flesh, and fubfiding again therein; provided they be kept in, as they eafily may, if we ufe not too fierce a fire to the evacuated receiver, whereby the lofs of thofe fweet vapours may be prevented.

PNEUMATICS

common air.

(191.) Jan. 21. 1679. I put pafte, without leaven, into an exhaufted re- Pafte boil'd in ceiver; and included another part of the fame pafte in a fecond receiver, vacuo, and in full of common air. I inclos'd thefe two receivers in Balneo Maria, ftopp'd with a screw; and when they had remain'd there, for three hours, expos'd to a moderate fire, I open'd the receivers: the pafte in vacuo I found reddish on the fuperficies; but the other had admitted water; and the paste was not boil'd enough: and, therefore, I put both receivers again in Balneo Maria, where they ftaid a whole night.

Jan. 22. This morning, I found the Balneum Maria quite cold; and the pafte, when taken out, was boil'd enough, but cover'd with no cruft. That which I included in vacuo, was interfpers'd with many cavities, but it feem'd too infipid; the other had no cavities, but a more pleasant taste. Both the receivers were found almoft wholly empty'd of air.

boil'd in Balneo

(192.) Feb. 3. 1679. I inclos'd leaven'd pafte in vacuo, and, as foon as it Leaven'd pafte had fill'd its receiver with factitious air, tranfmitted it into the receiver; I Marie, after it ufed to boil flesh in Balneo Maria; but, when the paste was thus remov'd, it had yielded its pitch'd much; yet, when it had remain'd for three hours in a hot Balneum Maria, the bread made of it was interfpers'd with many cavities, but cover'd with no crust.

air in vacuo.

water diftill'd

Feb. 5. I repeated the experiment, but now the pafte was included in vacuo, in the fame receiver, which was afterwards put in Balneo Maria; and therefore, there was no need to remove the pafte, and expofe it to the air. Hence, the bread made thereof, was much lighter than the former. (193) Feb. 12. I included rofemary, with water, in the diftilling veffel; Rosemary and and, when the air was pump'd out, I put the veffel in Balneo Arena, and in vacuo. there came over a water of a very fweet fmell, and fome drops of effential oil of a very sweet fcent, and not empyreumatical. But when I open'd the ftop-cock, to let in the air, the noife fo foon ceas'd, that I judg'd much air was produced from the rofemary.

Feb. 13. I put the fame rofemary into the fame evacuated veffel, and adminiftred a more intenfe fire, yet could extract no oil, fweet, or fetid; and the water was lefs fragrant than the former.

vacuo.

(194) Feb. 10. 1679. I boil'd one pound of flesh in vacuo, in a veffel Flesh boil'd in defcrib'd, which would contain almoft four pounds of water: its upper part, which was made of glafs, held the mercurial gage; by the help whereof, I perceiv'd, that the mercury afcended not three inches, tho'

VOL. II.

the

PNEUMATICS the flesh had boil'd for three hours, and more. It was not boil'd enough, and its pafte was ungrateful: the liquor, form'd of the condens'd vapours, had, alfo, an unpleasant taste.

Boiling in fcrew'd vessels or

water boil'd in

Feb. 11. I repeated the experiment, but now fprinkled the flesh with pepper and cloves: the mercury afcended to the height of fix inches, tho' the flesh boil'd no longer than the other: it feem'd very grateful to the palate; and the liquor, form'd from the vapours, had a moft pungent taste of pepper; but contracted nothing ungrateful from the flesh, as in the former experiment.

From thefe experiments, made in vacuo, it feems, that fuch veffels may be very useful for diftilling, and boiling of fuch bodies, as contain thin, and very volatile fpirits: for every thing will here be preferv'd, and nothing be fuffer'd to fly away.

(195.) Jan. 29. Eight days ago, I fill'd a screw-veffel, with beef and wadigestors and ter together; and when it had continu'd over a moderate fire for eight or first, beef and nine hours in Balneo Maria, ftopp'd alfo with a fcrew, I took the flesh out; Balneo Mariæ, but it was boil'd a great deal too much, and the tafte of it was very unpleafant. I boil'd other beef in the fame veffel, after the fame manner; only this was feafon'd with pepper and cloves, and remain'd expos'd to the fire but for three hours. This flesh preferv'd a moft pleasant tafte. I boil❜d other flesh, without fpices, for three hours, in the fame veffel, and after the fame manner: when the flesh was taken out, it tafted well; whence I conjectur'd, that what fpoil'd the first flesh, was over-boiling: yet the fpices may be convenient to correct fome part of the ungrateful tafte; for I left a place to condenfe the vapours, in the top of the veffel, and found, that the liquor, there formed, had an unpleasant tafte; but not fo when the flesh was feafon'd with pepper and cloves.

Apples boil'd in

(196) Jan. 29. I boil'd apples, after the fame manner as I did the flesh, Jereveel before mention'd; but mix'd no water with them. They were fet upon a moderate fire, for almost two hours. They were very foft, and of a very good tafte; but fome pieces, which lay in the upper part of the receiver, where the vapours afcending from the lower part condens'd, were of an unpleasant tafte; and the drops, form'd from the fame vapours, had an ungrateful fcent.

Flesh Season'd (197) February 4. I inciofed flesh, with pepper and cloves, in a receiwith Spice build ver ftopped with a fcrew, but ufed no water to fill up the interstices ; in a screw-veffel. only compreffed the flesh as much as I could, and then put the receiver is Balneo Maria, already hot, and ftopp'd it with a fcrew: when it had remained there, over a moderate fire, for an hour, the flesh was rather over-boil'd than under; but, when I open'd the Balneum Maria, all the water burst out of it, with a great force; the liquor being hot, and now finding vent.

Feb. 5. I inclofed fome part of this flesh in a receiver, ftopp'd with a fcrew.

March 12. The flesh included five weeks ago, was, this day, found very good. I do not doubt, but that perfect boiling contributed fomething to

its prefervation: for I find, by experiments made upon other bodies, that REUMATICO. boiling, the more perfect it is, hinders fermentation the more.

(198.) February 10. I boil'd a cow-heel, after the fame manner as I had done the flesh above-mention'd; but left it, for four hours, or more, upon a moderate fire: then, the veffels being unftopp'd, we found the flesh excellently well boiled, and the bones fo foft, that they might be easily cut with a knife, and eaten.

Feb. 12. I repeated the experiment, and let the veffels remain expofed to the fire for twelve hours; and tho' the water of the Balneum Maria every where secured the vessel immerfed in it, yet the flesh had contracted a very empyreumatical tafte and fmell; but the juice, which, in the former experiment, concreted into a very firm gelly, did not here congeal

at all.

Hence it appears, that many bones, and hard tendons, which we daily throw away as unprofitable, may, by the help of a Balneum Maria, ftopp'd with a fcrew, be converted into good nourishment.

cow-heel boil'

till the bones Tere tender.

a fcrew'd Balne

um

(199) February 10. I boil'd a fifh, after the fame manner, in a fcrew'd A fish boil'd in Balneum Maria, but mix'd no water therewith. The fifh remain'd upon am Maria. the fire for two hours only; when, the veffel being cool'd and open'd, it was found of a very good tafte; and its bones were fo foft, that they yielded to the preffure of the finger; and the head of it might be eaten like its flesh. The juice of it, in a fhort time, concreted into a gelly of a hard confiftence.

This method is useful for boiling fuch fifh as are very bony.

(200.) February 15. I put hart's-horn into a receiver, to be ftopp'd with Hart's-hors a fcrew, and fill'd the interftices with water; I included the receiver, thus bail'd foft. ftopp'd, in a fcrew'd Balneum Maria, and fo expofed it, for four hours, to a moderate fire: the veffels being open'd, the hart's-horn was found foft, and the juice foon concreted into a very firm gelly.

Feb. 17. I repeated the experiment, but no water was included with the hart's-horn, and the fire lafted fix hours under the Balneum Maria; after this, the hart's-horn was found very foft; but a little juice had fweat out of it, and adhered to the external parts of the hart's-horn, like drops of gelly.

The excellency of fuch a Balneum Maria appears from this experiment; for fince even hart's-horn can be boil'd by means thereof, without water, all the fresh water, ufually confumed in boiling flefh at fea, may be preferved for other ufes.

The objections against, the air's Spring examin'd.

A

DEFENCE

OF THE

Phyfico-Mechanical Experiments,

AGAINST

The Objections of FRANC. LINUS; his Hypothefis examined, and his Answers to particular Experiments confider'd.

UR author confeffes, that the air hath both a spring and weight; but denies that fpring to be great enough to perform what I afcribe thereto; and, particularly, labours to prove it unable, in a clofe place, to fuftain the mercury in the Torricellian experiment. For, fays he, "if a tube, only twenty inches long, be not entirely fill'd with quickfilver, but a fmall space be left betwixt it, and the finger that clofes the upper end, with nothing but air there; and the tube be open'd at the bottom, the finger will not only be drawn downwards; but the quick-filver will defcend, confiderably; that is, as far as fo fmall a parcel of air can be ftretch'd by the defcending weight; and, therefore, if, inftead of air, any other liquor, not fo eafily extended, be here ufed, the quick-filver will not fall: but, if the external air cannot fuftain twenty inches of mercury, how fhould it fupport twenty-nine and a half? But to this argument, he has himfelf furnifh'd us with an anfwer in thefe words."

ཊུ

But,

you'll fay that the mercury defcends, becaufe 'tis impell'd downwards, by "the air dilating itfelf by its own fpring." Which I think sufficient for the objection, notwithstanding the two exceptions he makes to it. For, firft, when he fays, that then "the finger ought rather to be repeli'd from, than fix'd to the tube, fince the expanfion is made every way;" he confiders not, that tho' the included air extends itself at firft, every way, yet the expanfion, in our cafe, muft neceffarily be made downward; becaufe, the finger that ftops the tube, being expos'd on the upper parts, and the fides, to the external air, has the whole weight and preffure of the atmo

fphere