Part 15
=ALCOHOLOM'ETER= (-l[)o]m'-). _Syn._ ALCOHOL'METER (h[)o]l'-; -h[)o]m'-[double-dagger]); ALCOHOLOMÉTRUM, L.; ALCOÖLOMÈTRE, ALCOÖMÈTRE, ALCOHOLMÈTRE, &c., Fr. An instrument or apparatus used in alcoholometry. Alcoholometers are simply 'hydrometers' adapted to the densities of alcohol, either concentrated or dilute. Some of these, as BAUMÉ'S, CARTER'S, &c., merely indicate the number of degrees corresponding to the state of concentration of the liquid. Others, of a like construction, as those of RICHTER (_a_), TRALLES (_b_), and GAY-LUSSAC (_c_), have their stems so graduated as at once to indicate the proportion per cent. of alcohol present, either by weight, or by volume, at some standard temperature. (See _engr._) A third class, as those of the Abbé BROSSARD-VIDAL, FIELD, &c. are essentially thermometers, with scales which indicate the boiling points of spirits of different strengths, instead of the common thermometric degrees; whilst to a fourth class belong the alcoholometer of M. SILBERMANN, which is based upon the known rate of expansion of alcoholic liquors by heat, expressed in alcoholometric degrees; and that of M. GEISSLER, which depends on the measurement of the tension of the vapour of the liquid, as indicated by the height to which it raises a small column of mercury. In SYKE'S HYDROMETER, used by officers of the Revenue, the scale of the instrument is enormously extended by the use of movable weights, with each of which it becomes, in fact, a separate instrument, adapted to a certain range of specific gravities.
A very convenient alcoholometer for ordinary purposes (_d_) has been lately produced by some of the instrument makers. It is of the usual form, but its stem on one side exhibits the per-centage richness of the sample in alcohol by volume; and on the other, the per-centage by weight. Thus, both results may be obtained at one trial. This instrument is sometimes called RICHTER'S ALCOHOLOMETER, in England. A further improvement, still more recently introduced, is a similar 'double-scale' instrument, showing the degrees of Sykes on one side, and carrying a small spirit-thermometer in the bulb, to which a scale is fixed ranging from 35° to 82° Fahr.
=ALCOHOLOM'ETRY.= _Syn._ ALCOHOL'METRY (-h[)o]l'-; -h[)o]m'-[double-dagger]); SPIRIT TESTING[double-dagger]; ALCOHOLME'TRIA, L.; ALCOÖLOMÉTRIE, ALCOÖMÉTRIE, &c., Fr. In _chemistry_, the art or process of ascertaining the richness of spirits in alcohol. In _commerce_, the determination of the quantity of spirit of a certain strength, taken as a standard, present in any given sample of spirituous or fermented liquors. In England, this standard is called "proof spirit."
_Hist., &c._ The great importance of being able accurately to determine the strength of spirits in the United Kingdom, on account of the high duties levied on them, has induced the Government authorities, at various times, to investigate the subject. In 1790, the matter was referred to Sir C. Blagden, then Secretary to the Royal Society, who instituted an extensive series of experiments to determine the real specific gravities of different mixtures of alcohol and water. The results of his labours and researches were put forward, with 'Gilpin's Tables,' in 1794, but no practical measures appear to have been taken in consequence. In 1832 a committee of the Royal Society, at the request of the Lords of the Treasury, examined into the accuracy of the Tables, and the construction and application of the instrument (SYKE'S HYDROMETER) now used by the Revenue officers, on which they reported favorably, and declared that they were sufficiently perfect for all practical and scientific purposes. The errors introduced into calculations of the strength of spirits by these tables were found to be quite unimportant in practice, and did not, in any one instance, amount to unity in the fourth place of decimals. This method adapts the specific gravity as the test of the strength of spirits, and is founded on the fact that alcohol is considerably lighter than water, and that (with proper corrections for condensation and temperature) the sp. gr. regularly increases, or decreases, according to the relative proportions in which the two are mixed.
Several other methods of alcoholometry have been proposed, founded upon--the variations in temperature of the vapour of alcohol of different strengths--the heat involved by its admixture with water--its dilatation by heat--the tension of its vapour--the insolubility of carbonate of potash in alcohol--its volatility, boiling point, &c. &c., the more important and useful of which are noticed further on. The method adopted by the Boards of Inland Revenue and Customs is, however, the one which is almost exclusively employed in trade and commerce in Great Britain, not only on account of its simplicity and correctness, but for the purpose of the results exactly coinciding with the results obtained by the Revenue officers.
METHODS OF ALCOHOLOMETRY.
1. _Methods based_ on the _specific gravity_, or _per-centage strength_, by VOLUME:--
_a._ With SYKES' HYDROMETER. _Revenue system._ The _engraving_ below represents Sykes' hydrometer, as made by Mr Bate, under the directions of the Commissioners of Inland Revenue and Customs. It consists of a spherical ball or float, with an upper and lower stem, and is made of brass, which (in the more expensive instruments) is usually coated with gold, to prevent corrosion from damp, and the acidity so generally present in spirituous liquors. The upper stem (A) is about four inches long, and is divided into ten parts, each of which contains five subdivisions. There are nine movable weights of the form _b_, of different sizes, numbered respectively 10, 20, 30, &c., to 90, each of which represents so many of the principal divisions of the stem, as its number indicates. In use, one of these weights is slipped on to the lower stems; and thus, by means of them, the instrument acquires a range of above 500 divisions, or degrees, extending from the Revenue 'standard alcohol' (sp. gr. ·825) to water. It is so formed as to give the sp. gr. with almost perfect accuracy, at 62° Fahr. When loaded with the weight 60 it sinks in proof spirit to the line marked (P) on the narrow edge of the stem at 51° Fahr.; and, by further placing the square weight or cap (also supplied with the instr.) on the top of the upper stem, it floats exactly at the same point in distilled water. This weight or cap is found to weigh 43·66 grs., which is practically 1-12th of the total observed weight of the instrument, and its poise 60, and hence shows the difference between the gravity of proof spirit and water, as explained hereafter. The whole is fitted up in a neat mahogany case, accompanied with a thermometer, and a book of tables containing corrections for temperature, &c.--_Process._ A glass tube of the form of fig. _B_ is filled to about the mark (_a_) with the sample for examination; the thermometer is then placed in the liquor, and stirred about for two or three minutes (observing not to breathe upon the glass, nor hold it in the hand), and the temperature noted. The hydrometer is next immersed in a similar manner, and gently pressed down in the liquor to the 0 on the stem with the finger; it having been previously loaded with any one of the nine weights that will cause it to float with the surface of the spirit at some point on the graduated part of the scale. The indication at the point cut by the surface of the liquor, as seen from below, added to the number of the weight with which the float is loaded, gives a number which must be sought in the hook of Tables, which is always sold with the instrument. In this book, at the page headed "Temperature as observed by the Thermometer," and against the part of the column appropriated to the given indication (weight), will be found the strength per cent., expressed in degrees over or under proof, by VOLUME, in whole numbers or decimal parts. In reading off the indication, to ensure accuracy, it is necessary to allow for the convexity of the liquor at the part where it immediately rests against the stem.
_Obs._ In an instrument requiring so much care and skill in its manufacture the purchaser should be careful to procure a perfect one. A very slight blow, friction from continual wiping with a rough cloth, and other apparently trivial causes, tend to injure so delicate an instrument. The shape of the weights occasionally vary; some being intended to be attached to the hydrometer at the bottom of the spindle, and others to rest on its top. The first plan is, perhaps, the best, as it tends to make the instrument float with greater steadiness in the liquor; but, at the same time, it renders its adjustment by the maker a matter of greater difficulty.
In employing this instrument, the Revenue officers are instructed to take the nearest degree above the surface of the mercury, when it stands between any two degrees of the thermometer; and the division on the scale of the hydrometer next below the surface of the liquid, when it cuts the stem between any two lines; thus giving the difference in favour of the trader in both cases.
By means of the _Table_ at page 64 the hydrometer indication, or the degrees over or under proof, of the Revenue system, may be converted into 'real specific gravities,' by mere inspection; and the corresponding 'per-centage richness' in alcohol of any sample may be found, either by WEIGHT or VOLUME.
The specific gravities in this table are such as, on being referred to Gilpin's Tables, will give the expressions of proof strength answering to the whole indications of the Revenue hydrometer. Intermediate values at fifths of indications may be had by taking proportional differences between the nearest tabular numbers. Thus, to find the specific gravity that should stand opposite to Indication 70·6, we first obtain the difference between the densities standing in a line with Indications 70 and 71 respectively, and then say, as 1 : 0·6 :: ·00192. 00·115, and ·94135 + ·00115 = ·94250, the specific gravity required.
_b._ With GLASS ALCOHOLOMETERS. That of Tralles, and most others of a like description (as made in England), gave the per-centage strength, by VOLUME, with tolerable accuracy, at the standard temperature of 60° Fahr. Gay-Lussac's ALCOÖMETRE, which closely resembles that of Tralles, is adjusted for the temperature of 59° Fahr. (15° Cent.). All of these, to give at once accurate results, must, of course, be employed at the 'normal temperature' of the instrument. As, however, in practice, the experiment cannot be conveniently performed at any 'fixed' temperature but only at that of the atmosphere, it is obvious that certain corrections are constantly required in order to obtain results of any value. Perfect accuracy requires that table for every variation of the thermometer, founded on actual experiments, should accompany each instrument; as, without them, tedious and difficult calculations are necessary, which, in the hurry of the cellar and laboratory, or by persons inexpert at figures, are not easily performed. A series of such Tables were prepared by Gay-Lussac, and, with his instrument, are those which are almost exclusively used in France. For rough purposes, in the absence of Tables or nicer calculations, it may be useful to know that, for commercial spirits, at ordinary temperatures, a variation of--
By VOLUME, 5° Fahr. is equal } 1·00% of Alcohol; } 1·794% of Proof to (about) } or (about) } spirit. 1° " " 0·20% " 0·359% " 5° Cent. " 1·80% " 3·229% " 1° " " 0·36% " 0·646% "
By WEIGHT, 5° Fahr. is equal } 0·80% of Alcohol; } 1·62% " to (about) } or (about) } 1° " " ·16% " ·32% " 5° Cent. " 1·43% " 2·9% " 1° " " ·28% " ·58% "
TABLE I.--_Showing the Densities and Values of Spirits at 60° Fahr., corresponding to every Indication of Sykes' Hydrometer._
+-----------+---------+----------+--------------------+ | | | | Per Cents. of | | Sykes' | | | Absolute Alcohol. | |Hydrometer |Strength | Specific +----------+---------+ |Indication.|per cent.| Gravity. | By | By | | | | | Measure. | Weight. | +-----------+---------+----------+----------+---------+ | | O.P. | | | | | 0 | 67·0 | ·81520 | 95·28 | 92·78 | | 1 | 66·1 | ·81715 | 94·78 | 92·08 | | 2 | 65·3 | ·81889 | 94·31 | 91·42 | | 3 | 64·5 | ·82061 | 93·84 | 90·78 | | 4 | 63·6 | ·82251 | 93·33 | 90·07 | | 5 | 62·7 | ·82441 | 92·80 | 89·36 | | 6 | 61·8 | ·82622 | 92·29 | 88·67 | | 7 | 60·9 | ·82800 | 91·77 | 87·99 | | 8 | 60·0 | ·82978 | 91·25 | 87·30 | | 9 | 59·1 | ·83151 | 90·74 | 86·63 | | 10 | 58·2 | ·83323 | 90·23 | 85·96 | | 11 | 57·3 | ·83494 | 89·72 | 85·30 | | 12 | 56·4 | ·83661 | 89·21 | 84·65 | | 13 | 55·5 | ·83827 | 88·70 | 84·00 | | 14 | 54·6 | ·83993 | 88·17 | 83·33 | | 15 | 53·7 | ·84153 | 87·67 | 82·70 | | 16 | 52·7 | ·84331 | 87·10 | 81·99 | | 17 | 51·7 | ·84509 | 86·51 | 81·26 | | 18 | 50·7 | ·84680 | 85·95 | 80·58 | | 19 | 49·7 | ·84851 | 85·39 | 79·89 | | 20 | 48·7 | ·85022 | 84·81 | 79·19 | | 21 | 47·6 | ·85205 | 84·19 | 78·44 | | 22 | 46·6 | ·85372 | 83·61 | 77·74 | | 23 | 45·6 | ·85537 | 83·04 | 77·07 | | 24 | 44·6 | ·85700 | 82·47 | 76·39 | | 25 | 43·5 | ·85878 | 81·85 | 75·66 | | 26 | 42·4 | ·86055 | 81·21 | 74·92 | | 27 | 41·3 | ·86229 | 80·59 | 74·19 | | 28 | 40·2 | ·86402 | 79·97 | 73·47 | | 29 | 39·1 | ·86574 | 79·34 | 72·75 | | 30 | 38·0 | ·86745 | 78·71 | 72·03 | | 31 | 36·9 | ·86915 | 78·08 | 71·32 | | 32 | 35·7 | ·87099 | 77·40 | 70·54 | | 33 | 34·5 | ·87282 | 76·71 | 69·77 | | 34 | 33·4 | ·87450 | 76·08 | 69·06 | | 35 | 32·2 | ·87627 | 75·41 | 68·32 | | 36 | 31·0 | ·87809 | 74·72 | 67·55 | | 37 | 29·8 | ·87988 | 74·03 | 66·79 | | 38 | 28·5 | ·88179 | 73·29 | 65·98 | | 39 | 27·3 | ·88355 | 72·60 | 65·23 | | 40 | 26·0 | ·88544 | 71·86 | 64·43 | | 41 | 24·8 | ·88716 | 71·17 | 63·68 | | 42 | 23·5 | ·88901 | 70·43 | 62·89 | | 43 | 22·2 | ·89086 | 69·69 | 62·10 | | 44 | 20·9 | ·89268 | 68·95 | 61·32 | | 45 | 19·6 | ·89451 | 68·21 | 60·53 | | 46 | 18·3 | ·89629 | 67·47 | 59·76 | | 47 | 16·9 | ·89822 | 66·67 | 58·92 | | 48 | 15·6 | ·89997 | 65·93 | 58·15 | | 49 | 14·2 | ·90182 | 65·14 | 57·34 | | 50 | 12·8 | ·90367 | 64·34 | 56·52 | | 51 | 11·4 | ·90551 | 63·54 | 55·70 | | 52 | 10·0 | ·90732 | 62·74 | 54·89 | | 53 | 8·6 | ·90913 | 61·94 | 54·09 | | 54 | 7·1 | ·91107 | 61·09 | 53·23 | | 55 | 5·6 | ·91299 | 60·24 | 52·38 | | 56 | 4·2 | ·91479 | 59·43 | 51·57 | | 57 | 2·7 | ·91666 | 58·58 | 50·73 | | 58 | 1·3 | ·91839 | 57·78 | 49·94 | | | U.P. | | | | | 59 | 0·3 | ·92037 | 56·86 | 49·04 | | 60 | 1·9 | ·92228 | 55·96 | 48·17 | | 61 | 3·4 | ·92408 | 55·10 | 47·33 | | 62 | 5·0 | ·92597 | 54·19 | 46·46 | | 63 | 6·7 | ·92798 | 53·22 | 45·53 | | 64 | 8·3 | ·92984 | 52·30 | 44·65 | | 65 | 10·0 | ·93176 | 51·36 | 43·76 | | 66 | 11·7 | ·93367 | 50·39 | 42·84 | | 67 | 13·5 | ·93586 | 49·34 | 41·86 | | 68 | 15·3 | ·93758 | 48·31 | 40·90 | | 69 | 17·1 | ·93949 | 47·29 | 39·96 | | 70 | 18·9 | ·94135 | 46·29 | 39·04 | | 71 | 20·8 | ·94327 | 45·20 | 38·04 | | 72 | 22·7 | ·94518 | 44·09 | 37·03 | | 73 | 24·7 | ·94709 | 42·96 | 36·01 | | 74 | 26·7 | ·94899 | 41·82 | 34·98 | | 75 | 28·8 | ·95092 | 40·63 | 33·92 | | 76 | 31·0 | ·95288 | 39·40 | 32·82 | | 77 | 33·2 | ·95484 | 38·10 | 31·68 | | 78 | 35·6 | ·95677 | 36·76 | 30·50 | | 79 | 38·1 | ·95877 | 35·32 | 29·24 | | 80 | 40·6 | ·96068 | 33·90 | 28·01 | | 81 | 43·3 | ·96259 | 32·41 | 26·73 | | 82 | 46·1 | ·96457 | 30·77 | 25·32 | | 83 | 49·1 | ·96651 | 29·08 | 23·88 | | 84 | 52·2 | ·96846 | 27·31 | 22·38 | | 85 | 55·5 | ·97049 | 25·39 | 20·77 | | 86 | 59·0 | ·97254 | 23·41 | 19·11 | | 87 | 62·5 | ·97458 | 21·39 | 17·42 | | 88 | 66·0 | ·97660 | 19·41 | 15·78 | | 89 | 69·4 | ·97857 | 17·46 | 14·16 | | 90 | 72·8 | ·98057 | 15·51 | 12·56 | | 91 | 76·1 | ·98261 | 13·58 | 10·97 | | 92 | 79·2 | ·98452 | 11·85 | 9·56 | | 93 | 82·3 | ·98657 | 10·04 | 8·08 | | 94 | 85·2 | ·98866 | 8·28 | 6·65 | | 95 | 88·0 | ·99047 | 6·83 | 5·48 | | 96 | 90·7 | ·99251 | 5·25 | 4·20 | | 97 | 93·3 | ·99448 | 3·80 | 3·03 | | 98 | 95·9 | ·99658 | 2·31 | 1·84 | | 99 | 98·2 | ·99851 | ·997 | ·793 | | 100 | ... | 1·00000 | ... | ... | +-----------+---------+----------+----------+---------+
This Table {above} has been copied, by permission, from Loftus's 'Inland Revenue Officer's Manual,' and its correctness verified by W. H. Johnston, Esq., Surveying General Examiner.
TABLE II.--_Table for finding the Specific Gravity of any Spirit at 60° Fahr., when the Specific Gravity at any other Temperature is given._
Water taken as 1000. +-----------------+----------+-----------------+----------+ | |Correction| |Correction| |Specific gravity.| for each |Specific gravity.| for each | | | degree. | | degree. | +-----------------+----------+-----------------+----------+ | 810 to 820 | ± ·475 | 910 to 920 | ± ·434 | +-----------------+----------+-----------------+----------+ | 820 " 830 | ± ·473 | 920 " 930 | ± ·424 | +-----------------+----------+-----------------+----------+ | 830 " 840 | ± ·472 | 930 " 940 | ± ·406 | +-----------------+----------+-----------------+----------+ | 840 " 850 | ± ·471 | 940 " 950 | ± ·381 | +-----------------+----------+-----------------+----------+ | 850 " 860 | ± ·471 | 950 " 960 | ± ·340 | +-----------------+----------+-----------------+----------+ | 860 " 870 | ± ·466 | 960 " 970 | ± ·269 | +-----------------+----------+-----------------+----------+ | 870 " 880 | ± ·460 | 970 " 980 | ± ·165 | +-----------------+----------+-----------------+----------+ | 880 " 890 | ± ·456 | 980 " 990 | ± ·090 | +-----------------+----------+-----------------+----------+ | 890 " 900 | ± ·450 | 990 " 1000 | ± ·084 | +-----------------+----------+-----------------+----------+ | 900 " 910 | ± ·442 | | | +-----------------+----------+-----------------+----------+
Thus, by making the proper ADDITION to the apparent strength per cent., when the observed temperature is BELOW the normal temperature of the instrument, or a corresponding SUBTRACTION, when it is ABOVE it, the strength of the sample may be determined sufficiently near for all practical purposes.
The following Table, taken from Loftus's 'Inland Revenue Officer's Manual,' will be found of great value in making these corrections, and has the merit of being easily applied.
An example will show how this Table is to be used.
_Example._--If a quantity of spirit is of the sp. gr. 894 at 73°, what will be its sp. gr. at 60°?
Here the sp. gr. being between 890 and 900, we must add ·450 for each degree of temperature between 73° and 60°. The sp. gr. at 60° would, therefore, be 894 + (·450 × 13) = 899·85. When the temperature is below 60°, the correction for each degree must be subtracted. When, however, very accurate results are desired, and the necessary Tables are not accessible, the sample for trial must be brought to the normal temperature of the instrument, in the manner explained under HYDROMETRY.
_c._ From the SPECIFIC GRAVITY. The temperature having been taken by a thermometer, and the specific gravity ascertained by any of the usual methods, but preferably by means of an accurate glass hydrometer, it merely becomes necessary to refer to Table I, where, against the number expressing the specific gravity, the alcoholic content per cent., by volume, of the sample examined, will be found for 60° Fahr., subject to the corrections just referred to, when the temperature is either above or below this point.
If the precise specific gravity sought cannot be found in the _Table_, the difference between it and the next greater specific gravity must be taken for the numerator of a fraction, having for its denominator the difference between the greater and the next less specific gravity in the table. This fraction, added to the per-centage of alcohol in the fourth column of the table, opposite the greater sp. gr., will give the true per-centage sought. Thus, the sp. gr. ·96051 is not in the table, and the next greater number is ·96068; the former must, therefore, be deducted from the latter, and the difference (17) put as the numerator of the fraction, having for its denominator 191, the difference between ·96068 and ·95877. The fraction (17/191) ·089, so found, added to the per-centage strength opposite ·96068 in the third column, gives 33·989 as the true per-centage of alcohol in the given sample.
The per-centage by volume may be converted into per-centage by weight, by multiplying the former by ·793811, the sp. gr. of absolute alcohol, and dividing the product by the sp. gr. of the sample. The quotient is the number of pounds of alcohol in 100 pounds of the given spirit. Thus:--Suppose 1000 grains by measure of alcohol to weigh 950·92 grains, and to contain (see Table I) 40·63 per cent. by volume of absolute alcohol, what per cent. by weight does the sample contain?
·793811 × 40·63 = 32·25254093, and this product divided by ·95092 = 33·917, the true per-centage by weight of absolute alcohol in the sample.
2. Method based on the specific gravity, or per-centage strength by WEIGHT:--
The specific gravity is ascertained and the Table used in precisely the same manner as in the "method by volume," already described.