Specific With a fmall funnel fill the bottle quite full of redGravities wine, and place it in the veffel CD, which is to be full of water. The wine will presently come out of the bottle, and rife in form of a fmall column to the furface of the water; and at the fame time the water, entering the bottle, will fupply the place of the wine; for water being fpecifically heavier than wine, muft hold the loweft place, while the other naturally rifes to the top. A fimilar effect will be produced if the bottle be filled with water, and the veffel with wine for the bottle being placed in the veffel in an inverted pofition, the water will defcend to the bottom of the veffel, and the wine will mount into the bottle. Fig. 3. In the fame manner we may pour four different liquors, of different weights, into any glafs-veffel, and they fhall all ftand feparate and unmixed with each other. Thus, if we take mercury, oil of tartar, fpirit of wine, and spirit of turpentine, fhake them together in a glafs, and then let them fettle a few minutes, each fhall ftand in its proper place, mercury at the bottom, oil of tartar next, fpirit of wine, and then fpirit of turpentine above all. Thus we fee liquors different denfities; and this difference it is that the hydrometer is adapted to compare. In general, all vinous fpirits are lighter than water; and the lefs they contain of water, the lighter they are. The hydrometer, therefore, will inform us how far they are genuine, by fhowing us their lightnefs; for in pure fpirit of wine it finks lefs than in that which is mixed with a fmall quantity of water. are of very The hydrometer fhould be made of copper: for ivory imbibes fpirituous liquors, and thereby alters their gravity; and glass requires an attention that is incompatible with expedition. The moft fimple hydrometer confifts of a copper ball Bb, to which is foldered a brafs wire AB, one quarter of an inch thick. The upper part of this wire being filed flat, is marked proof, at m, fig. 4. because it finks exactly to that mark in proof fpirits. There are two other marks at A and B, fig. 3. to fhow whether the liquor be one-teuth above or below proof, according as the hydrometer finks to A, or emerges to B, when a brafs weight, as C or K, is fcrewed to its bottom c. There are other weights to fcrew on, which show the specific gravity of differ. ent fluids, quite down to common water. may The round part of the wire above the ball be marked fo as to reprefent river-water when it finks to RW, fig. 4. the weight which anfwers to that water being then fcrewed on; and when put into fpring water, mineral-water, fea-water, and water of falt fprings, it will gradually rife to the marks SP, MI, SE, SA. On the contrary, when it is put into Brifol water, rain-water, port-wine, and mountain-wine, it will fucceffively ink to the marks br, ra, po, mo. Inftruments of this kind are fometimes called areometers, There is another fort of hydrometer that is calculated to afcertain the fpecific gravity of fluids to the greatest precifion poffible, and which confits of a large hollow ball B, fig. 5. with a smaller ball & ícrewed on to its bottom, partly filled with mercury or small fhot, in order to render it but little fpecifically lighter than water. The larger ball has alfo a fhort neck at C, into which is fcrewed the graduated brafs-wire AC, which, by a small weight at A, caufes the body of the inftrument to defcend in the fluid, with part of the item. When this inftrument is fwimming in the liquor Specific contained in the jar ILMK, the part of the fluid dif- Gravities. placed by it will be equal in bulk to the part of the inftrument under water, and equal in weight to the whole inftrument. Now, fuppofe the weight of the whole to be four thousand grains, it is then evident we can by this means compare the different dimentions of four thousand grains of feveral forts of fluids. For if the weight at A be fuch as will cause the ball to fink in rain-water till its furface come to the middle point of the ftem 20; and after that, if it be immerfed in common fpring-water, and the furface be obferved to ftand at one-tenth of an inch below the middle point 20; it is apparent, that the fame weight of each water differs only in bulk by the magnitude of one-tenth of an inch in the ftem. Now, fuppofe the ftem to be ten inches long, and to weigh a hundred grains, then every tenth of an inch will weigh one grain and as the ftem is of brafs, which is about eight times heavier than water, the fame bulk of water will be equal to one-cighth of a grain, and confequently to the one-eighth of one fourthoufandth part, that is, one thirty-two thousandth part of the whole bulk. This inftrument is capable of ftill greater precifion, by making the item or neck confift of a flat thin flip of brafs, inftead of one that is cylindrical: for by this means we increase the forface, which is the moft requifite circumftance, and diminifh the folidity, which neceffarily renders the in ftrument ftill more accurate. To adapt this inftrument to all purposes, there fhould be two items, to fcrew on and off, in a small. hole at a. One ftem fhould be a finooth thin flip of brafs, or rather fteel, like a watch fpring fet ftraight, fimilar to that we have juft now mentioned; on one fide of which is to be the feveral marks or divifions to which it will fink in different forts of water, as rain, river, fpring, fea, and falt-fpring waters, &c.; and on the other fide you may mark the divifions to which... it finks in various lighter fluids, as hot Bath water, Bristol water, Lincomb water, Cheltenham water, port-wine, mountain, madeira, and other forts of wines. But here the weight at A on the top mult be a little. lefs than before when it was used for heavier waters. But in trying the itrength of the fpirituous liquors, a common cylindric item will do beit, because of its strength and iteadinefs: and this ought to be fo contrived, that, when immerfed in what is called prooffpirit, the furface of the fpirit may be upon the middle point 20; which is eafily done by duly adjulling the fmall weight A on the top, and making the ftem of fuch a length, that, when immer fed in water, it may juft cover the ball and rife to a; but, when immerfed in pure fpirit, it may rife to the top A. Then, by dividing the upper and lower parts 20 and A 20, into. ten equal parts each, when the inftrument is immersed: into any fort of fpirituous liquor, it will immediately fhow how much it is above or below proof. Proof-fpirit confifts of half water and half pure fpirit, that is, fuch as, when poured on gun powder, and. fet on fire, will burn all away; and permits the powder to take fire and flafh, as in open air. But if the fpirit be not fo highly rectified, there will remain fome water, which will make the powder wet, and unfit to take fire. Proof-fpirit of any kind weighs feven pounds twelve ounces per gallon. The Specific The common method of fhaking the fpirits in a Gravities. phial, and railing a head of bubbles, to judge by their manner of rifing or breaking whether the fpirit be proof, or near it, is very fallacious. There is no way to certain, and at the fame time fo eafy and expeditious, as this by the hydrometer. 14 New im 15 Objection A variety of different constructions of the hydromeproved hy ter have recently been made with a particular view drometer. of improving the inftrument, fo as to afcertain the ftrengths of fpirits, and worts in brewing, in the molt eafy and accurate manner. As it would be unne ceffary to defcribe all of them here, we fhall conclude this fection with defcriptions of thofe only which have been most approved and are now in general ufe. The Cufto Clarke's. toms have for a long time adopted an hydrometer of an old conftruction, by the late Mr Clarke. It differs very little from the one above described (fig. 3.4.); and has belonging to it a great variety of weights, which are occafionally fecured on to the bottom of the ftem: This renders the inftrument troublefome and complicated in its ufe, and where dispatch in bufinefs and accuracy are wanted, not fo commodious as fuch an inftrument fhould be. 16 Hydrometer made by Jones. An hydrometer upon a very fimple conftruction, eafy in its application, and fufficiently accurate for the common purposes it is wanted to anfwer, by diftillers and others concerned in the fale and ftate of fpirits, is made by Mr Wm. Jones mathematical inftrument maker in Holborn. It requires only three weights, to difcover the frengths of fpirits from alcohol down to water. This hydrometer, like others, is adjufted to a temperate ftate of the air, or 60° of the thermometer with Fahrenheit's fcale; but as an altera tion of this temperature very materially affects the gravity of fpirits, caufing them by the inftrument to appear ftronger when the weather is hotter, and the contrary, it has been found indifpenfably neceffary to place a thermometer in the fpirits previous to the immerfing of the inftrument, and make a juft allow. ance for the feveral degrees that the mercury may be above or below the temperature above mentioned. This has been usually, though inaccurately, eftimated at the rate of one gallon allowance for every three degrees of the thermometer above or below 60°; viz. for every three degrees warmer, reckoning the spirit one gallon in the 100 weaker than what is fhown by the hydrometer; and for every three degrees colder than 60°, allowing one gallon in the 100 ttronger. In this hydrometer, the thermometer is united with the inftrument; and from experiment its divifions are adjusted to the different degrees above or below the temperate ftate. The concentration is alfo confidered in this inftrument, which is the mutual penetration of fpirit and water when mixed together; which in trong fpirits is fo confiderable as to caufe a diminutution of 4 gallons in the 100: for example, if to 100 gallons of fpirit of wine, found by the inftrument to be 66 gallons in the 100 over proof, you add 66 gallons of water in order to reduce it to a proof flate; the mixture, inftead of producing 166 gallons, will produce 62 gallons only of proof fpirits, and therefore 4 gallons will be lott in the mutual penetration of the particles of the water and fpirit. Fig. 6. is a reprefentation of the whole inftrument, with the thermometer united. Its length A B is about 9 inches; its ball C, is of the fhape nearly of an egg, and made of hard brafs, and about 1 inches N° 161. in its horizontal diameter. It has a fquare ftem AD, Specific 17 Hydrometers of a fimilar conftruction, and with no more weights, Mr Jones makes for difcovering to great exactness the different ftrengths or specific gravity of worts in brewing, of different minerals, fea waters, &c. For these purposes the thermometer is not united with the inftrument; but is found to be more ufeful feparately, and of a larger dimention. Notwithftand- One by Mr ing the above hydrometer anfwering the general purpo- Dicas with fes in an accurate and eafy manner, yet the induftry of a fliding feveral ingenious perfons interested in the fale of fpirits rule. has been exerted to conftruct an inftrument of the greateft poffible exactnefs. The effects of heat and cold upon different ftrengths of fpirits not being fo uniform as generally understood, and every different degree of ftrength of fpirit between water and alcohol having its peculiar degree of contraction and dilatation, errors of fome importance must be found in the hydrometers conftructed upon the ufual principle of temperature. With a view to obviate this defect, Mr Dicas of Liverpool conftructed fome years back an hydrometer of the form ge Specific generally used, with 36 weights, which were valued Gravities from 0 to 370, including the divifions on the item; but the improvement confifts folely in an ivory fliding rule which accompanies the inftrument. In the graduation of this rule, is considered the different effects of heat and cold above-mentioned on the fpirits. Every degree of ftrength included by the hydrometer between o and 370, has the fame series of numbers placed on the fliding part of the rule; opposite to which, on the fixed rule, are marked the different ftrengths, and which are thus determined by immediate infpection. They proceed on one fide from water to proof, and on the other from proof to alcohol, and divided in such a manner, as to fhow how many gallons in the 100 the fpirits are above or below proof. There is also a line, containing the concentration for every degree of ftrength; and, what is the chief advantage of the rule, at one end of the fide is placed a scale, containing the degree of heat from 30 to 80 of Fahrenheit's scale, with a flower de luce oppofite, as an index, to fix it to the temperature of the fpirits. By the affiftance of this fliding rule, the exact ftate of the fpirits is correctly obtained. A perfect comprehenfion of this rule can only be had by an infpection of it, and it always accompanies the hydrometer on fale. Mr Dicas has obtained a patent for his improvement. 18 Mr Quin's univerfal hydronic ter. An hydrometer of a more universal conftruction has been made by Mr Quin, who for many years has been accustomed to conftruct hydrometers of various kinds. This hydrometer is made of hard brafs; and therefore not fo liable to be injured as fine copper, of which hy. drometers are ufually made: it is conftructed so as to afcertain, in a plain and expeditious manner, the ftrength of any spirit from alcohol to water, with the concentration and specific gravity of each different ftrength; and discovers alfo the weight of worts, &c. with four weights only; which, according to the old construction of hydrometers, would require a far greater number of weights. Fig. 8. is a reprefentation of the inftrument, with its four fides of the ftem graduated and figured at top, to correfpond with the weights below. The fide of the fquare-ftem engraved A, B, C, D, &c. to Z, fhows the ftrength of any spirit from alcohol to water; and the three other fides, numbered 1, 2, 3, are adapted for worts, &c. The heat and cold altering the density of fpirits, and giving to every degree of ftrength a peculiar degree of contraction and dilatation; this circumftance is confidered in dividing the fliding rule belonging to and fold with the hydrometer. This fliding rule is nearly fimilar to that of Mr Dicas's abovementioned, and differs but very little from it. Some directions for the ufe of this hydrometer may further exemplify its fimplicity and accuracy. Find the heat of the fpirit by a thermometer, and bring the ftar on the fliding rule to the degree of heat on the thermometer scale, and against the number of the weight and letter on the flem you have the ftrength of the spirit pointed out on the sliding rule, which is lettered and numbered as the inftrument and weights are. The weights apply on the under ftem at C. Example. Suppofe the heat of the fpirit 65° by the thermometer, and of such strength as to fink the hy drometer to D on the ftem, without any weight; then put the far (on the rule) to 65 of the thermometer, VOL. IX. Part I. and againft D you have 75 gallons to the 100 over Specific proof; at this ftrength the concentration is 5 gallons Gravities. (marked above 75); and the specific gravity is nearly 811, as marked below D: fo that if 75 gallons of water are added to 100 gallons of this fpirit, the mixture will be hydrometer proof; but will only produce in measure 170 gallons. Again, let the heat be 50°, and the spirit require the weight no 1. to fink the inftrument to I on the ftem; then put the ftar to 50° of heat, and against I on the fliding rule you have 52 gallons to 100 over proof, concentration 24 gallons, and the fpecific gravity 854. If the inftrument with the weight n° 2. fhould fink to Q on the ftem, and the heat 41°, it shows the ftrength 19 gallons to the 100 over proof, concentration, fpecific gravity 905. If the fpirit be at 32° of heat, and the weight no 3. finks the inftrument to letter S on the ftem on the fliding rule, it fhows the liquor to be 13 gallons in the 100 under proof, concentration, specific gravity 945. So of the reft. In afcertaining the ftrength or gravity of worts, the weight n° 4. is always to continue on the hydrometer; and the weights n° 1, 2, 3, are adapted to the fides n° 1, 2, 3, of the square ftem; which discovers the exact gravity of the worts. The inftrument is adjusted fo as to fink in rain water at 60° of the thermometer with the weight n° 1. to W, on the fide of the ftem n° 1. and shows to 26° heavier than water. The fide n° 2. with its correfponding weight n° 2. fhows from 26° to 53°, and the fide n° 3. afcertains from 53° to 81°, or 40 pounds per barrel heavier than water; two degrees on the ftem being a pound per barrel. To ufe the hydrometer in afcertaining the gravity of two or more worts. Rule. Multiply the gravity of each wort by its refpective number of barrels or gallons; divide the fum of the products by the number of gallons or barrels ; the quotient will be the mean gravity required. Suppose first wort 30 barrels, 60° gravity, 20 barrels, 35° gravity. When the heat of the worts cannot be conveniently tried at 60° of the thermometer, the following fmall table shows the number of divifions to be added for the heat: Degrees of the thermometer 60 O Degrees of theh ydro meter to be added. This table is not philofophically true; yet the error from it will not exceed a quarter of a pound per barrel in any gravity, and for fermentation; but for more accuracy in this particular Mr Quin completes a scale which may be applied to any particular degree of heat. Mr B |