WAT
WAT
be made a neutral one, by mixing fome acid, and then the water filtred and diftilled again. By thefe methods the •water of vegetables is procured pure ; and this is the way of proving, that the chemical principle water is lodged in, and may be feparated from all fuch fubflances. Shaw's Lectures, p. 150. Cwy/w/-Waters. In the making of all compound fpirituous liquors, or, as they are called by the apothecaries, cordial- waters, the great care is to ufe a pure and well -rectified fpirit, as nearly irifipid as poffible, that the flavour of it may not mix among the flavours of the other ingredients. It is the general cuftom to ufe. the proof-fpirit, but it would be infinitely better to ufe the alcohol, or totally inflamma- ble ; partly, as the ftrength of the water would be much better afeertained that way, the proof ftrength determined by the crown of bubbles being very vague and uncertain, and that of the alcohol or totally inflammable fpirit perfectly fixed and certain ; and becaufe this fpirit is always more free from the oil of the ingredient it is made from, and on that account not only approaches more to that fo much defired thing, a pure and taflclcfs fpirit, but being free from oil of its own is the more hungry, the more ready to imbibe that of the ingredients added to it, and has no over- powering tafte to give of its own.
If the method of ufing alcohol he not chofen, let a fine, clear, and pure melafi.es fpirit of the proof ftrength be ufed, without any farther addition of water in the ftitl, an addi- tional quantity of water only taking up room to very bad purpofe, and prolonging and prejudicing the operation ; and when alcohol is employed, it fhould only be mixed with an equal quantity of pure water, to, reduce it to the proof ftrength. When the choice of a fpirit is thus fettled, the next thing to be had regard to is the matter of digeftion, for without this many ingredients will not part with their fla- vour and virtues at all, and many others but very imper- fetSHy. Cinnamon in particular, if not macerated in the fpirit a long while before diftillation, will not part with its heavy oil, which will therefore be left in the ilill, and thrown away, while the {lightly impregnated fpirit is faved. When the ingredients have flood a due time in digeftion, according to their feveral natures, the fpirit is to be drawn from them in the manner that belt tends to bring over their virtues, whereon the character and expectation of the water is founded ; fo if the ingredients naturally abound in a heavy vifcous oil, the operation fhould be performed with a brifker fire, than when the oil is thin, light, and etherial. Thus ftrong cinnxman- water, after a fufficient digeftion to loofen the oil, may be drawn over fmarter, or with a brifker fire, than citron-water, the fpirit of mint, or the like, in which the oil of the ingredient is thin, and will eafier afcend with the fpirit.
The capital thing in this compound diftilling r efts here, that a fufficient quantity of the fine eflential oil of the ingredients be received into, and mixed with the fpirit, while the groffer, lefs fubtile, and lefs agreeable oil is thrown out. To effect this to any degree of perfection, requires that the operation be well conducted from the beginning, that the receiver be changed in due time, and that the fpirit be pru- dently made up.
When no regard is had to thefe three particulars, as is ufu- ally the cafe among the apothecaries, the conlequence is, that the cordial-water becomes a thick, turbid, and milkv liquor, and taftes more like what the diftillers call faints, than like a cordial-water, and is fitted to give hcknefs rather than to cure it. At leaft, before it can be ufed, it mull either {land a long time to fine itfelf, if ever it will fine, or have its grofs and terreftrial parts precipitated by art. On the contrary, when thefe rules are prudently obferved, the water proves, without farther trouble, clean tailed, clear, brifk, pleafant, and refrefhing.
The diftillers in general make their compound waters in a much neater manner than the apothecaries ; and what has led them into the way of doing fo, is their ftriit obfervance of the bubble proof, a thing which the apothecaries feem either not to underftand, or to pay very little regard to. The diftillers, in the making of their compound waters, find, that if they let the faints run in among the clear fpirit, it kills the proof, as they call it, before the time ; hence they are inftru£ted to leave the faints out, and to make up the fpirit with pure water, referving the faints to other ufes, to which they are better adapted, as containing a ccpious oil; or they let the frill work longer than the procefs for making the water would require, and by this means obtain a. larger quantity' of oil than is commonly imagined : this they preferve fepatate, if the oil of only fome one ingredient; and they fell large quantities of the oils of juniper, anife and caraway, and the like, to the druggifts, chemifts, and apo- " thecaries. But this is a very fcandalous cheat on the buyer, for there is a very great difference between a pure and clear elTential oil, that is perfect and intire, and fuch a one as has, in this manner," -been robbed of its lighter and finer parts by diftillation with a fpirituous menftruum. It is a general rule in this bufinefs to change the receiver as foon as the fpirit runs proof, and make up the quantity with Append. Vol. II.
water ; in this cafe, the whole is certain to be clean and fine ; but there are fome cafes, as in particular in the diftilling of cinmmon-water, where a fmall quantity of the faints ought to be fuffercd to come into the fpirit : but this is to be ob- ferved by way of flint, that fo much is never to be allowed of the faints as will make the water milky; for the water fhould always be kept in the ftate of full proof, as it mellows and ripens, as they exprefs it, much fooner in tins than in any other ftate. But if the cuftom could be univerfullv in- troduced, it would be better that all the waters, kept by the apothecaries, mould be juit in the ftate in which they came over, that is, three fifths of the quantity of the proof fpirit put into the Itill : if this were generally brought about, it would be eafy for the phyficians to regulate the dofes in their prefcriptions accordingly ; every draught and julep that they entered into would be the better for it. Sbavfs Eilay 011 Diftillery.
Dr. Shaw in another treatife, after obferving that the apothe- caries ufually fucceed but ill in diftilling cordial- waters, lays down the four following rules, by the obfervance of which the art ot making thefe waters might he brougbt to great perfection.
The firft is, to ufe a well-cleanfed (pint that is freed from its own eflential oil, for as the defign of compound diftilla- tion is to impregnate a fpirit with the citential oil of the in- gredients, it ought firft to be deprived of its own. The fecond rule is, to (bit the time of the digeftion of the ingredients to their tenacity, or the ponderofity of their oil : thus rhodium wood and cinnamon require to be longer di- geftcd, before they are diftilled, than calamus aromaticus, or lemon-peel. Sometimes alfo cohobation, or the pouring r;f the fpirit already difrillcd back upon the ingredients, pruves neceflary, as particularly in making the ftrong cinnamon- water, where the eflential oil is extremely ponderous, and difficultly rifes along with the fpirit without this cohobation. The third rule is, to fuit the degree of fire, or ftrength of the diftillation, to the ponderofity of the oil intended to be raifed with the fpirit : thus ftrong c'\r.i\:\mon-zcater fhould be diftilled oft brifker than the fpirit of mint or balm. The fourth rule is, that a due proportion of only the finer eflential oil of the ingredients be thoroughly united, or in- corporated with the fpirit, fo as to keep out the grofler and lefs fragrant oil. This may chiefly be effe&ed by leaving out the faints, and making up to ftrong proof with fine font water in their itead.
The addition of fugar to cordial waters is a thing of little moment, and may therefore be omitted. If the four rules before laid down be duly obferved, there is no occafion for diftilling in balnco mariae, nor for fining down waters with alum, whites of eggs, ifinglafs, or the like, for they will be prefently bright, fweet, and pleafant tailed, without any farther trouble. $b,au?§ Le£):ures 3 p. 127. Motion of Water, in hydraulics. The theory of the mo- tion of running water is one of the principal objects of hydraulics, and many eminent mathematicians have applied themfelvcs to this fubject. But it were to be wifned that their theories were more confident with each other, and with experience. The curious may confult Sir Ifaac Nsw- tgn's Principles, lib. 2. prop. 36. with the comment. Dan. Bernoulli's Hyurodynamica. "Jo. Bernoulli, Hvdraulica, Oper. Tom. IV. p. 389, feq. Dr.Jurin, in the Fhilcf. Tranfac- tions, N* 452, and in Dr. 'Martynh Abridg. Vol. VIII. p. 282, feq. 'aGravefande, Phyfic, Elem. Mathernat. lib. 3. pars 2. Polenus, de Caftellis, and others. Mr. MacLau- rin, in his Fluxions, art. 537, feq. has illuftrattd Sir Ifaac Newton's doctrine on this intricate fubject, which ftill, not- withftanding the labours of all thefe eminent authors, re- mains in a great meafurc obfeure and uncertain. Even the fimpleft cafe of the motion of running water, which is when it ifiues from a. hole in the bottom of a vefiel kept con- ftantly full,, has never yet been determined, i'o as to give univerfai fatisfaction to the learned. We fhall here mention fome of the phenomena of this motion, as itated by Dr. Jurin from Poienus.
1. The depth of the water in the velTd, and the time of flowing out being given, the meafure of the effluent water is nearly in proportion to the hole.
2. The depth of the water, and the hole being given, the meafure of the effluent tuatcr is in proportion to the time.
3. The time of flowing out, and the hole being given, the meafure of the cfHuent water is nearly in a fubduplicate pro- portion to the height of the water.
4. The meafure of the effluent water is nearly in a ratio compounded of the proportion ot the hole, the proportion of the time, and a fubduplicate proportion ot the depth of the water.
5. The meafurc cf the ivater flowing out in a given time, is much lefs than that which is commonly affigned by ma- thematical theorems. For the velocity of effluent water is commonly fuppofed to be that which a heavy body would acquire in vacuo in falling from the whole height of the water above the hole ; and this being fuppofed, if we call the area of the hole F, the height of the water above the hole A, the velocity which a heavy body acquires in falling
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