Cooley's Cyclopaedia of Practical Receipts Volume I Part 22

---------------+------------+----------------+------------ Alcohol Alcohol Boiling point. per cent. Boiling point. per cent.

Fahr. by volume. Fahr. by volume.

---------------+------------+----------------+------------ 20534 5 17996 55 19922 10 17942 60 1958 15 1787 65 19238 20 17762 70 18950 25 17654 75 18716 30 17546 80 185 35 17492 85 18338 40 1742 90 18212 45 17314 95 18158 50 172 100 ---------------+------------+----------------+------------

TABLE V.--_Showing the_ BOILING POINTS _of 'under proof' spirit._ By Dr URE.

----------------+-------------+--------------- Boiling points. Per-centage Corresponding Fahr. strength. Sp. Gr.

----------------+-------------+--------------- 1785 Proof. 9200 17975 10 U.P. 9321 1804 20 " 9420 1821 30 " 9516 1834 40 " 9600 1856 50 " 9665 189 60 " 9729 1918 70 " 9786 1964 80 " 9850 202 90 " 9920 ----------------+-------------+---------------

_Obs._ This method does not answer well with spiritous liquor above 'proof,' owing to the variations of their boiling point being so slight as not to be easily observed with accuracy; but with liquors under 'proof,'

and particularly with wines, beer, and other fermented liquors, due care being observed, it gives results closely approximating to those obtained by distillation, and sufficiently accurate for all ordinary purposes. In testing strong alcoholic solutions it is, therefore, proper to dilute them with twice their bulk of water; and commercial spirits, with an equal bulk of water; the results obtained being doubled or tripled as the case may be.

[Ill.u.s.tration]

_d._ From the EXPANSION of the LIQUID when heated: Silbermann's DILATATOMETER. The expansion of alcohol between 0 and 212 Fahr. is triple that of water; and between 77 and 122 Fahr. it is much greater.

Between -14 and -98 Fahr. the rate of expansion is about the 00047th part in volume for every degree of Fahrenheit's scale. The measurement of this expansion has been proposed as a new and ready method of alcoholometry, adapted to nearly all spirituous and fermented liquors.

Silbermann's instrument, which is based on it (see _engr._), simply consists of a flat bra.s.s or ivory plate (_A_), on which are fixed a mercurial thermometer (_D_) graduated from 22 to 50 Cent. (= 77 to 122 Fahr.); and the DILATATOMETER (_B_), which is a gla.s.s pipette open at both ends. A valve of cork, or vulcanised india rubber, closes the tapering end (_c_); this valve is attached to a movable rod (_C_) which is fastened to the supporting-plate, and connected with a spring (_f_) and a handle (_g_) bearing a four-threaded screw, by which the lower orifice of the pipette can be opened or closed at will. In use, the pipette is filled with the liquor under examination, to a little above the zero point (0) on the scale. This is effected by suction, by means of a little piston of leather (_i_), which fits tightly in the long and wider limb of the pipette; the valve (_d_) being previously opened by turning the k.n.o.b (_h_). The proper quant.i.ty of liquor being introduced, and the lower end closed, the piston is moved up and down two or three times, for the purpose of drawing the air-bubbles and absorbed air out of the liquid, the presence of which would vitiate the results of the trial. To allow the piston to be withdrawn without any shock, or the danger of dividing the column abruptly, the rod attached to it is made hollow throughout. In using it the operator applies the ball of his forefinger to the top of the piston-rod (_E_), in order to create a vacuum as he raises it; and then withdraws it, to readmit the air when he thrusts it down or removes it from the tube. The excess of liquid (if any) in the pipette is then run off until its upper surface is exactly level with the zero (0) of the scale, at 25 C., to which it is raised by immersion in a water bath of that temperature, as observed by the thermometer; which is done by very cautiously turning the rod which depresses the valve. The whole apparatus is now again immersed in the water bath; and, held by the upper portion of the plate, kept in gentle motion with the hand, until the temperature rises to exactly 50 C., when the coefficient of expansion is obtained, and hence also the proportion of alcohol--the scale of the instrument being so graduated, from actual experiments previously made upon mixtures of known composition, as to give, at once, the per-centage of alcohol by VOLUME (nearly).[14]

[Footnote 14: 'Comptes Rendus,' xvii, 418.]

[Ill.u.s.tration]

_e._ From the TENSION of the VAPOUR:--Geissler's ALCOHOLOMETER. This method, for which we are indebted to M. Geissler, of Bonn, depends on the measurement of the tension or elastic force of the vapour of the liquid, as indicated by the height to which it raises a small column of mercury.

The spirit, wine, or other liquor, of which it is desired to ascertain the strength, is put into the little flask (_a_), which, when completely filled, is screwed on to the curved gla.s.s-tube which contains the mercurial column (which is inverted for the purpose), and is closed by the stop-c.o.c.k (_b_). The instrument (see _engr._) is then placed erect, and the flask and lower part of the tube immersed in a water bath, as in the previous method. The number, on the graduated scale of the instrument corresponding to the height of the mercury, at the boiling point of the liquor under examination, gives the per-centage of alcohol by VOLUME (nearly).

This method furnishes approximative results with great facility and expedition; and, with proper care, these do not vary more than 1/3 to 1/2 of 1%, from those obtained by distillation. We find, that by having the diameter of the part of the tube at which the surface of the mercury is acted on by the vapour a little larger than that of the longer limb, and by previously abstracting the air from the sample, as in Silbermann's method, or even by agitation and exposure in an open vessel, the two may be made to correspond almost exactly.

_f._ From the DIFFERENCE between the sp. gr. BEFORE and AFTER ebullitiom:--Taberie's method and NOMETER. The sp. gr. of the sample is first accurately determined by any of the usual methods. It is next carefully evaporated, in an open vessel, to one half its volume. The residuum, when cold, is made up with pure water to exactly its original measure at its original temperature, and the sp. gr. again ascertained.

The difference between the two being due to the spirit originally present, furnishes the means of calculating a new sp. gr., from which the per-centage richness of the sample may be obtained by mere inspection of the Tables. The observed sp. gr. is the true one, whenever the liquor, after ebullition and restoration to its original volume, has the same sp.

gr. as water (_i. e._, 1000), at 60 Fahr. Taberie employs a peculiar instrument, which he calls an nometer; but its use is not essential to his method of alcoholometry. The results are, of course, only approximative, though sufficient for all ordinary purposes. Prof. Mulder, however, says that he prefers it to any of the previous methods; and that the results, with care, are almost as accurate as those obtained by distillation.

_g._ By means of CARBONATE OF POTASH:--

_g. a._ (Brande's Method.) The liquor for trial is poured into a long, narrow gla.s.s tube (graduated centesimally), until the vessel is half-filled, and, after the solution of about 12% or 15% of a strong solution of subacetate of lead, or a little finely powdered litharge, is agitated until the colour is entirely, or nearly removed. Anhydrous carbonate of potash, in powder, is next added, until it sinks undissolved, even after prolonged agitation of the liquid. The whole is now allowed to repose for a short time, when the alcohol is seen floating on the top of the aqueous portion of the liquid in a well-marked stratum. Its quant.i.ty, read off by means of the graduations of the tube, and doubled, gives the per-centage richness of the sample in alcohol, by volume.

This process answers well with cordials, wines, and the stronger ales; but with very weak liquors it is not to be relied on. The whole operation may be performed in two to five minutes, and (with these exceptions) furnishes very reliable approximative results. In most cases the decolouring part of the process may be omitted. The alcohol thus separated has a sp. gr. of from 8061 to 8118, and contains 3% or 4% of water; but for ordinary purposes it may be regarded as pure alcohol.

4. Alcoholometry of MINUTE QUANt.i.tIES of liquid. When only a few drops, or a quant.i.ty too small for the application of the preceding methods, can be obtained, an organic a.n.a.lysis may be had recourse to, and the quant.i.ty of absolute alcohol calculated from that of the resulting carbonic anhydride and water; care being previously taken to free the sample from other volatile bodies, if it contains any of them.

_Gen. commentary._ The duties on spirits in England are charged on the number of proof gallons they contain, which is ascertained by gauging or weighing the spirit, and then trying its strength by Sykes' hydrometer.

The per-centage of proof spirit multiplied by the number of gallons gives the net amount of proof spirit to be charged.

'PROOF STRENGTH' is an arbitrary standard, adopted for the purpose of facilitating calculations, for which it is well suited; although pure alcohol would, for this purpose, be more simple. As defined by Act of Parliament, 58 Geo. III, c. 28, "proof spirit" is such "as shall, at the temperature of 51 of Fahrenheit's thermometer, weigh exactly twelve thirteenth parts of an equal measure of distilled water."

Taking, therefore, water at 51 Fahr. as unity, the sp. gr. of "proof spirit" at 51 Fahr. is 12/13 of 1000 or 92308. When such spirit is raised to the temperature of 60 Fahr., its density is 91984.

Spirit at "proof" contains very nearly equal weights of absolute alcohol and water; the exact proportions according to recent experiments are:--

--------------------------------------------------------------------- By VOLUME. By WEIGHT. --------------------------------------- Sp. gr. at Bulk before Bulk after admixture 60 Fahr. admixture. and condensation. ----------------+-----------------+---------------------------------- Alcohol. Water. Alcohol. Water. 10000 + 10308 10000 + 8180 17523 } 91984 4924 + 5076 5706 + 4668 10000 } ---------------------------------------------------------------------

The standard alcohol of the Revenue authorities, and that on which Gilpin's Tables are founded, is a spirit of the sp. gr. 825 at 60 Fahr., which is said to contain, by weight, 89% of pure alcohol of 796; and 926% of alcohol, by volume, which corresponds to about 625 o. p.

It is of great importance to the spirit dealer to be able to estimate correctly the number of 'proof gallons' in any quant.i.ty of his commodities, or in the whole or any portion of his stock, as disagreeable errors frequently result from ignorance on this point. Calculations of this kind are extremely simple. Thus, when we find, by the hydrometer, that a given sample of spirit is 10 per cent. over-proof, it means, that 100 gallons of such spirit contain as much alcohol as 110 gallons of proof spirit.

In over-proof spirit, the per-centage o. p. always represents the quant.i.ty of water which the given spirit requires to reduce it to proof. By adding this per-centage over-proof to 100, we obtain a number which, multiplied by any number of gallons, and divided by 100, gives the exact number of proof gallons which is contained in any quant.i.ty of the spirit referred to. Thus:--A puncheon of rum gauged at 91 galls., and shown by the hydrometer to be 21 o. p., contains--

21 o. p. of sample added to 100 121 No. of gallons of rum 91 ------ 11011

No. of gal. of proof-spirit = 11011 / 100 = 11011

In like manner when a spirit is said to be 11 u. p., or under-proof, it means that 100 gal. of such spirit contains 11 gal. of water, and 89 gal.

of 'proof spirit.' By deducting the per-centage under-proof from 100, we not only obtain the number of proof gal. contained in 100 gal. of such spirit, but, as in the last case, a factor which multiplied by any number of gal., and divided by 100, gives the exact number of 'proof gallons'

contained in any quant.i.ty of the given strength. Thus:--An ullage brandy piece containing 45 gal. of spirit at 10 u. p., would have the proof value of--

Per cent. u. p. of sample 10, } subtracted from 100 } 90 No. of gall 45 --- 4050

Quant.i.ty of proof spirit = 4050 / 100 = 4050

Or exactly 40-1/2 gallons.

The strength of absolute alcohol (sp. gr. 7938) is estimated at 75-1/4% over-proof. It therefore contains 175-1/4% of 'proof spirit,' whilst proof spirit (sp. gr. 91984) contains 5706% of 'absolute alcohol,' both being by measure or volume. Thus--

(meas. of alc. 175-1/4) / 100 = equiv. meas. of pf. spt.

And--

(meas. of pf. spt. 5706) / 100 = equiv. meas. of abs. alc.

From which we derive the 'constant multipliers' 17525 (or roughly 1-3/4), and 5706, applicable to any number of volumes or gallons. For--

meas. of alc. 17525 = equiv. meas. of pf. spt.

and--

meas. of pt. spt. 5706 = equiv. meas. of alc.

To ascertain what quant.i.ty of a spirit at any given strength is equiv. to or contains 100 lbs. of absolute alcohol, we have only to divide the constant number 22077 by the proof value per cent. of such spirit.[15]

Thus--for a spirit 12 u. p.--this would be

[Footnote 15: This number is obtained thus:--

100 /79381 = 126 (nearly),

126 17525 = 22077.

100 - 12 = 88% of proof spirit;

and--