may happen to burft. Perhaps it will be neceffary to throw away the contents, to wash the vessel with water (because the boiling matter will stick between the necks of these veffels, and will cement them together) and to begin the operation afresh. But if the powdered chalk is thrown in, without any confiderable flake of the machine, there will be but a fmall effervefcence at the beginning. When this operates well, the veffel C will foon be filled with water, and the veffel B half filled with air; which when done will

ther trouble, provided the fupply of fixed air be copious: and still more fo, if it is there compreffed any way. It will be of some advantage to fhake the whole apparatus very gently, once or twice in every hour: In this cafe the water may be impregnated by the fixed air, in four hours, and perhaps lefs.

It was, however, to

avoid even this delay, that I invented the following additional veffels, by means of which the whole operation is confiderably fhorter.

chine.

nutes.

Whenever the effervefcence nearly ceases in the veffel A, it will be revived again by giving it a gentle fhake, fo that fome part of the powdered chalk which is in a heap at the bottom of A, may be mixed with the diluted vitriolic acid, and difengage more fixed air. However, when it happens that the whole is exhaufted, and no more air rushes up to the middle veffel from the lower one, either more powdered chalk must be put in, or more oil of vitriol; or at laft more water, if neither of the two firft produced the defired effect. Thefe additions may be performed by letting them in, either through the opening m, or through the mouth of the veffel A. In this cafe ufe must always be made of the funnel y, in order to avoid the fticking of the junctures above-mentioned. If thefe veffels be fuffered to ftand fix or feven hours, the water will be fufficiently impregnated, without any fur

BESIDES the two veffels B and C (fig. 1.), I have added two others perfectly alike, reprefented by G and H (fig. 2.). The veffel H is finished with a ftopple i, either of a conical form, or equally perforated as the other w: this velel contains half as much as the veffel G. Both thefe veffels are fet upon the wooden ftand F; and the lower neck of the veffel G is not only furnished with a valve and ftopple, as already defcribed, when speaking of the veffel B; but. it is fitted, and ground air-tight, to the neck of the fame veffel A; and has an opening 1, with a ground ftopple, which is only opened when occafion requires, as will be mentioned hereafter.

The wooden ftand K (fig. 3.) is fo contrived, that a thick piece of glafs x, like a fmall tumbler, muft be cemented on the top, after it has been ground air-tight to the under neck of the veffel B and G. The form of this ftand is eafily conceived by fig. 3, it being plain at the bottom, turns up in a kind

K4

a kind of convexity z z towards its edge, and has a round moulding , which hinders its tumbling, when moderately pushed fideways.

under the furface of the water in the veffel B.

It will fuffice to fhake the water in this manner during two or three minutes; which done, loofen the upper veffel C, fo that the re

Machine.

THE two middle veffels B and G (fig. 1. and 2.), are to be filled with pure water, and put on the ftands K and E, with their upper ones C and H, as in the figure. The mixture of oil of vitriol, water, and powdered chalk, or rather marble, must be done in the fame manner, as was faid in p. 134. par. 2d. and finally the veffels B and C are to be put on the veffel A. as was faid p. 134. par. 4th, and following. But as foon as the veffel C is filled with water, thrown up by the air, which diflodges it from the veffel B, through the crooked tube 1, 2, both thefe veffels B and C are to be removed together as they are, from the veffel A, to the ftand K (fig. 3.), and the other veffels GH, which are in the and F, are to be put in their ftead, upon the veffel A. Whilft the operation is going on in thefe laft, you must hold the veffels B C, which are in the ftand K, by the neck and ftopple w with your right hand, and the under neck V with your left: incline them a little fideways, and fhake them very brifkly, fo that the water within B, be very much agitated, prefenting many fresh furfaces in contact with the fixed air; the greatest part of which will be abforbed into the water: as it will foon appear, by the end of the crooked tube being confiderably

veffel B; and the unabforbed air may go out. Then taking off thefe veffels from the ftand K, put them, joined together as they are, on the ftand F. By this time the veffel G will be half filled with fixed air; and the upper veffel H will be filled with the water thrown up by it. Take then these veffels to the ftand K, and replace the others B C, on the mouth of the veffel A, after letting out the unmixed air, as aforefaid; fo that thefe veffels may be half filled again with fixed air, whilft the water in the veffels G H is brifkly fhaked in the fame manner, as the others have been.

When this operation has been repeated three, or at moft four times alternately, with each fet of veffels, throwing out the remaining air which does not incorporate with the water, after it has been brifkly fhaked; and adding fresh quantities of fixed air, with which it must be well agitated; in this cafe, the water contained in both the veffels B and C, will be fully fatue rated in a few minutes.

Thefe artificial mineral waters, are much more pleafant to tafte, than the natural Pyrmont or Seltzer's waters, which, befides their fixed air (the only part perhaps which affords their renewed virtues, and which is hardly half of what this artificial water may abforb) contain fome difagreeable faline tafte: and it is known that

this alone does not contribute at all to their medicinal virtues; but, on the contrary, it must be hurtful in fome complicated cafes.

The artificial waters will remain as limpid, and as tranfparent as before, although there has been abforbed above as much air as their own bulk. The whole procefs will hardly take above a quarter of an hour, by this method; and the quantity will be double of that which could be made in the fimple glafs machine.

The water may be taken out by the opening or n, to be drank im mediately; if not, it will be bet ter to let it remain in the machine, where it has no communication with the external air; other wife the fixed air goes off by degrees, and it becomes vapid and flat; as it happens alfo to the naE tural acidulous waters. Thefe artificial waters, may, however, be kept a very long time, in bottles well corked, placed with their mouths downwards.

In general they are fo fimilar to the natural acidulous waters, that they may be even made to fparkle like Champaign wine. Mr. Warltire has actually brought thefe waters to this state, by keeping the fixed air compreffed upon the furface of the water, in the middle veffel; as appears by his letter printed in the Appendix to your third volume of Experiments and Obfervations on Air, page 366. The fame end will be obtained, if, inftead of the stopples w and i, ufe is made of the folid one, reprefented (fig. 7.) which has a kind of a bafon at the top, in order to hold fome additional weight. This ftopple must be of a conical figure, and very loofe; but fo well ground

and fmooth in its contact, as to be air-tight by its preffure, which may be increased by fome additional weights in its bofom. If the veffels are ftout enough, there is no danger of their bursting in the operation.

Thefe waters may also be rendered ferugineous (or chalybeate) very easily, by putting in the middle veffel, two or more flender phials, filled with cuttings of fine inombinding wire; otherwife with fmall iron nails; because the impreg nated water will diffolve the iron fo faft, as to become well faturated with it in a few hours, according to the experiment of Mr. Lane If the iron nails, or the cuttings of wire, were not confined in the fmall phials, but let loofe in the middle veffel; their ruft or fediment would foon stop the paffages of the fixed air from the under vef fel: in fuch a cafe, the vessel A must burft, and the whole machine be broken into pieces.

According to Sir John Pringle, there may be added to each pint of thefe waters, from eight to ten drops of tinctura martis cum fpiritu falis, in order to refemble more nearly the genuine Pyrmont water. But the method of rendering chalybeate thefe artificial waters, used by Dr. Hulme, is to add one grain of falt of steel to each pint (16 ounces) of water already impregnated with fixed air. There is no doubt but these artificial waters may be advantageously employed in many medical purposes; not only by diffolving in them the very falts which are found to be contained in many natural fprings, renowned for their different virtues; but by applying them fimply, without any other mixture. The

fame

fame able phyfician, Dr. Hulme, has lately published an Account of different Cafes and Experiments, by which it clearly appears, that fixed air, adminiftered internally, has a powerful action for diffolving the ftone in the bladder, and against nephritic complaints. Its efficacy is equally beneficial againft the fcurvy, the gout, the fevers, even the hectick ones with confumption, the dyfentery, and the worms *. Thefe artificial waters may be even applied as a vehicle to many draughts, and internal medicines, which will be then lefs naufeous to the patients, and perhaps more agreeable to the ftomach, giving to it a tonical ftrength.

The advantages derived from fixed air in economical purposes, deferve to be taken notice of in this place. Mr. William Lee, and his neighbours at Hartweil, did preferve fresh meat perfectly fweet for ten days, which was as long as

they had occafion for in the last hot weather of this fummer (1778), one of the hotteft we ever had in this country; and this was obtained by washing the meat two or three times a day, with water impregnated with fixed air; even meat that had begun to change was totally recovered by the fame procefs, as the faid gentleman afferted in a letter I have feen, direted to a friend of mine.

I fhall conclude this fubject by obferving with you, that fixed air may be given to wine, beer, cyder, and to almoft any liquor whatfoever. Even when beer has become flat, or dead, as it is called, it may be revived by employing the fame method: but the delicate, though brifk, and agreeable fla vour, or acidulous taste, communicated by the fixed air, and which is fo manifeft in water, will hardly be perceived in wine, or other li quors, which have much taste of their own.

ANTIQUITIES.

Account of the firft Inflitution of the Office of Poet Laureat. From Warton's Hiftory of English Poetry.

GR

REAT confufion has enter ed into this fubject, on account of the degrees in grammar, which included thetoric and verfification, anciently taken in our univerfities, particularly at Ox. ford on which occafion a wreath of laurel was prefented to the new graduate, who was afterwards ufually ftyled Poeta Laureatus. Thefe fcholaftic laureations, however, feem to have given rife to the appellation in queftion. I will give fome inftances at Oxford, which at the fame time will explain the nature of the ftudies for which our academical philologifts received their rewards. About the year 1470, one John Watson, a student in grammar, obtained a conceffion to be graduated and laureated in that science, on condition that he compofed one hundred Latin verfes in praife of the univerfity, and a Latin comedy. Another grammarian was diftinguifhed with the fame badge, after having ftipulated, that, at the next public act, he would affix the fame number of hexameters on the great gates of St. Mary's church, that they might be feen by the whole univerfity. This was at that period the moft convenient mode of publication.

About the fame time, one Maurice Byrchenfaw, a fcholar in rhetoric, fupplicated to be admitted to read lectures, that is, to take a degree, in that faculty; and his petition was granted, with a provifion, that he fhould write one hundred verses on the glory of the univerfity, and not fuffer Ovid's Art of Love, and the Elegies of Pamphilus, to be ftudied in auditory. Not long af terwards, one John Bulman, another rhetorician, having complied with the terms impofed, of explaining the first book of Tully's Offices, and likewife the first of his Epittles, without any pecuniary emolument, was graduated in rhetoric; and a crown of laurel ́ was publicly placed on his head by the hands of the chancellour of the univerfity. About the year 1489, Skelton was laureated at Oxford," and, in the year 1493, was permitted to wear his laurel at Cambridge. Robert Whittington affords the last inftance of a rhetori-' cal degree at Oxford. He was a fecular pricft, and eminent for his various treatifes in grammar, and for his facility in Latin poetry: having exercised his art many years, and fubmitting to the cultomary demand of an hundred verfes, he was honoured with the laurel in the year 1512. This title is prefixed to one of his grammatical fyftems: ROBERTI