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 to (about) | 1·00% | of Alcohol; or (about) | 1·794% | of Proof spirit. |
| 1° | ” | ” | 0·20% | ” | 0·359% | ” |
| 5° | Cent. | ” | 1·80% | ” | 3·229% | ” |
| 1° | ” | ” | 0·36% | ” | 0·646% | ” |
By Weight,
| 5° | Fahr. | is equal to (about) | 0·80% | of Alcohol; or (about) | 1·62% | ” |
| 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.
| Sykes’ Hydrometer Indication. | Strength per cent. | Specific Gravity. | Per Cents. of Absolute Alcohol. | |
| By Measure. | By 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.