PYRMONT WATER. 



troduce tlie end of the pipe into the mouth of the vedel of 

 water, as in the drawing, and begin to agitate the chalk and 

 water brifl<ly. This will prefently produce a conhderable 

 quantity of fixed air, which will dillend the bladder ; and 

 this being preii'ed, the air will force its way through the pipe, 

 and afcend into tlie velfel of water, the water at the fame 

 timedefcending, and coming into the bafon. 



When about one-half of the water is forced out, let the 

 operator lay his hand upon the uppermolt part of the veffel, 

 and fhake it as briildy as he can, not to throw the water out 

 of the bafou ; and in a few minutes the water will abforb the 

 air, and taking its place, will nearly fill the vellel as at tiie 

 firft. Then (hake the phial containing the chalk and water 

 again, 3ind force more air into the veflel, till, upon the 

 whole, about an equal bulk of *air has been thrown into it. 

 Alfo fhake the water as before, till no more of the air can 

 be imbibed. As foon as this is perceived to be the cafe, the 

 water is ready for ufe ; and if it be not ufed immediately, 

 ftiould be put into a bottle as foon as poflible, well corked, 

 and cemented. It will keep, however, very well, if the 

 bottle be only well corked, and kept with the mouth down- 

 wards. 



It may be proper to obferve on this procefs, that the 

 phial, e, fhould always be placed conliderably lower than the 

 vefiel'fl ; that the water to which the chalk is put (hould be 

 changed after every operation ; that with a veflel of water 

 holding three pints, and a phial containing the chalk and 

 water of ten ounces, a little more than a tea-fpoonful of oil 

 of vitriol will produce air enough to impregnate fuch a quan- 

 tity of water, that the whole procefs does not take up more 

 than a quarter of an hour, and the agitation not five minutes ; 

 and that in this method the water is ealily made to imbibe an 

 equal bulk of air ; whereas Dr. Brownrigg found that Pyr- 

 mont water at the fpring-head did not contain fo much 

 as one-half. This apparatus has received confiderable im- 

 provements, which we Ihall briefly recite ; but in jullice 

 to the merit of the original inventor, his method deferves 

 to be recorded ; and befides, it requires lefs time, and 

 is much lefs expenfive than thofe that are now generally 

 ufed. 



The apparatus contrived by Dr. Nooth, and improved by 

 Mr. Parker, is reprefented in Jig. 2. It is made of glafs, 

 and ftands on a wooden veflel, d d, refembling a tea-board ; 

 the middle veflel B has a neck, which is inferted into the 

 mouth of the veflel A, to which it is ground air-tight. This 

 lower neck of the veflel B has a glafs itopple S, compofed 

 of two parts, both having holes fufficient to let a good 

 quantity of air pafs through them. Between thefe two parts 

 is left a fmall fpace, «^ontaining a plano-convex lens, which 

 afts like a valve, in letting the air pafs from below upwards, 

 and hindering its return into the veflel A. The upper veffel 

 C terminates below in a tube ;-<, which, being crooked, 

 hinders the immediate afcent to the bubbles of fixed air into 

 that veflel, before they reach the furface of th.e water in the 

 veflel B. The veflel C is alfo ground air-tight to the upper 

 neck of the middle vciTel B, and has a ftopple, p, fitted to 

 its upper mouth, which has a hole through its middle. The 

 upper veflel B holds jufl half as much as the middle one B ; 

 and the end, /, of the crooked tube goes no lower than the 

 middle of the veilel B. 



For the ufe of this apparatus, fill the middle veflel B 

 with fpring or any other wholcfome water, and join to it the 

 veflel C. Pour water nito the vefl'i'l A (by the opening m, 

 or otherwife) fo as to cover the rifing part of its bottom : 

 about three-fourths of a pint will be fufficient. Fill an 

 ounce phial with oil of vitiiol, and add it to the water, fliaking 

 the veflel fo as to mix tliem well together. As heat is gene- 



rated, it will be bed to add the oil by a little at a time, 

 otherwife the veflel may be broke. Put to this, through a 

 wide gljfs or paper funnel, about an ounce of powdered raw 

 chalk, or marble. White marble being firft granulated, or 

 pounded like coarfe fand, is better for the purpofe than 

 pounded chalk, bccaufe it is harder ; and, therefore, the 

 aftion of the diluted acid upon it is flower, and lafts a confi- 

 derable time. On this account the fiipply of fixed air from 

 it is more regular than with the chalk : and befides, when 

 no more air is produced, the water may be decanted from 

 the veflel A, and the white fediment waftied off, and the re- 

 maining granulated marble may be employed again, by adding 

 to it frefh water and a new quantity of oil of vitriol. The 

 funnel in this procefs is made ufe of in order to prevent the 

 powder from touching the infide of the veflel's mouth : for 

 if that happens, it will flick fo Itrongly to the neck of the 

 veflel B, as not to admit of their being feparated without 

 breaking. Place immediately the two veflcls B and C (faf- 

 tened to each other) into the mouth of the veflel A, as in 

 the figure, and all the fixed air wliicli is difengaged from the 

 chalk or marble by the oil of vitriol, will pafs up through 

 the valve in S into this veflel B. When this fixed air comes 

 to the top of the veflel B, it will diflodge from thence as 

 much water as is equal to its bulk : which water will be 

 forced up through the crooked tube into the upper veflel C. 



Care muft be taken not to fliake the veflel A when the 

 powdered chalk is put in ; otherwife a great and fudden 

 effervefcence will enfue, which will perhaps expel part of 

 the contents. In fuch cafe it may be necefl^ary to open a 

 little the ftopple *, in order to give vent, otherwife the 

 veflel A may burlt. It will be proper alfo to throw away 

 the contents, and wafh the veflel ; for the matter will ftick 

 between the necks of the veflels, and cement them together. 

 The operation muft then be begun afrefli. But if the chalk 

 be thrown in witiiout fliaking the machine, or if marble be 

 ufed, the effervefcence will not be violent. If the chalk be 

 put into the veflel loofely wrapt up in paper, this accident 

 wiUbe ftill better guarded againft. When the effervefcence 

 goes on well, the veffel C will foon be filled with water, and 

 the veffel B half filled with air ; wliich will eafily be known 

 to be the cafe, by the air going up in large bubbles through 

 the crooked tube r /. 



When this is obferved, take off the two veffels B and C 

 together as they are, and fliake them fo that the water and 

 air within them may be much agitated. A great part of 

 the fixed air will be abforbed into the water ; as will appear 

 by the end of tlie crooked tube being confiderably under the 

 furface of the water in the veffel. The ftiaking them for 

 two or three minutes will be fufficient for this purpofe. 

 Thefe veflels muft not be fliook while joined to the under one 

 A, otherwife too great an effervefcence will be occafioned in 

 the litter; together with the ill confequences above-men- 

 tioned. After the water and air have been fufficiently agi- 

 tated, loofen the upper veffel C, fo that the remaining wa- 

 ter may fall down into B, and the unabforbed air pals out. 

 Put thefe veffels together, and replace them into the mouth 

 of A, in order that B may be again half filled with fixed air. 

 Shake the veffels B and C, and let out the unabforbed air as 

 before. By repeating the operation three or four times, the 

 water will be fufficiently impregnated. 



Whenever the effervefcence nearly ceafes in the veffel A, 

 it may be renewed by giving it a gentle fhake, fo that the 

 powdered chalk or m.arbleat the bottom may be mixed with 

 the oil of vitriol and water above it ; for then a greater 

 quantity of fixed air will be difengaged. 



When the effervefcence can be no longer renewed by 

 ftiaking the veffel A, either more chalk muft be put in, or 



more 



