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TABLE No. 2.*

To be used in the Distillation Process.

Degrees of Spirit Indication, with corresponding Degrees of Gravity lost in MALT AT GRAIN

worts.

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The following particulars of an experiment made upon a beer brewed at a gravity of 1050 will illustrate the method pursued :Beer gravity

1006.40 Spirit

992:10 Extract

1014.18 In estimating the acid, 46 divisions of the measure tube were emptied, or 460 fluid grains of the ammonia solution were required to neutralise the beer, which was thus shown to contain 0.46 per cent. of acetic acid ; then Acetic acid present in the beer

0•46 per cent. Deduct, as being already allowed for in the formation of table No. 2 :: 0.10

0:36

Acetic acid to be taken account of..
Observed degrees of spirit indication, or 1,000 minus the sp. gr. of

the distillate

}7.90

Add spirit indication, corresponding to 0-36 per cent of acid

, as per {0-47

True spirit indication

8:37
which by table No. 2, corresponds to 35.75 degrees of gravity lost,
Then 8.37 Spirit Indication is equal to 35.75 degrees of gravity

Add extract graviiy 1014:18
Original gravity 1049.93

* This is the only Table given in Acts of Parliamont.

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It now remains to describe the « Evaporation Process,” which differs from the preceding method in this, that no direct account is taken of the amount of alcohol present in the beer. A certain bulk of the beer is evaporated down, in an open vessel, until the whole of the alcohol is driven off, the residue is then made up to the original bulk by the addition of distilled water, and its density, or the “extract gravity,” ascertained; the beer « gravity is then determined, which, when deducted from the « extract gravity,” gives the apparent spirit indication ; this last quantity is then corrected for the acetic acid present, in precisely the same manner as in the previous method; the spirit indication thus obtained, represents a greater number of degrees of gravity lost than those corresponding to an equal indication derived from the «distillation process.” Table No. 2 is, therefore, now inapplicable, and the annexed table, No. 3, based also upon experimental data, must be used. The cause of this disparity between the spirit indications afforded by the two processes was first explained by Professor Graham and his colleagues in their report on original gravities; they found that if equal quantities of alcohol be added to equal bulks of pure water and beer, an unequal condensation of volume takes place, the density of the former being lowered by the presence of the alcohol somewhat more than that of the latter, unequal amounts of alcohol being thus indicated. Now, the spirit indication is, in the “ distillation process,” derived from the specific gravity of the distillate, which consists of alcohol mixed with pure water, while in the evaporation process it is found by deducting the “ beer gravity” from the extract gravity, so that the spirit indication given by the former process represents a less amount of gravity lost than does that obtained by the latter process.

The following is the table of degrees of spirit indication with corresponding degrees of gravity lost, used with the “evaporation process ” :

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TABLE No. 3.

To be used in the Evaporation Process. Degrees of Spirit Indication with corresponding Degrees of Gravity lost in MALT or GRAIN

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3.8

6.6

0 1 2 3 4 6 6 7 8

3.5 7.4 11:5 15.8 20.3 24.8 29.5 34.3 40:0 44.9 50.3 55.6 61.0 66.5 72.0

7 4.2 82 12:4 16.6 21.2 25.6 30 4 35.5 41.0 46.0 51:4 56.7 62:1 676

1.0 4.6 8.7 12.8 17.0 21.6 261 30.9 36.0 41:5 46.5 51.9 67.3 62:7 68.1

1:4 5.0 9.1 13.2 17.4 22:1 26.6 31:3 36.6 42-0 47:1 52:5 57.8 63 2 68.7

1.7 5.4 9.5 13.6 17.9 22.5 27.0 31.8 37.1 42.5 47.6 53:0 58.3 63 8 69.2

2.1 5.8 9.9 14.0 18.4 23:0 27.5 32.3 37.7 43.0 48.2 53.5 68.9 64.3 69.8

2.4

3:1 7.0 11:1 15.3 19.8 24.3 29.0 33.8 39:4 44:4 49.8 55.0 60.5 66.0 71.4

7-8 11.9 16.2 20.7 252 30.0 34.9 40 5 45.4 50.9 56.2 61.6 67.0

6.2 10:3 14:4 18.8 23:4 28.0 32.8 38.3 43.5 48.7 54.0 59.4 64.9 70-4

10.7 14.8 19.3 23.9 28.5 33.3 38.8 44.0 49.3 54:5 59.9 65.4 70.9

10 11 12 13 14 16

The data given in the experiment above quoted will furnish an example of the mode of arriving at the original gravity by this method. Extract gravity

1014.18
Beer
:: ::

1006:40

do...

7.78

Spirit indication
Add spirit indication corresponding to 0.36 per cent. of

acetic acid

}

0:47

8.25 which by Table No. 3 represents 35.75 degrees of gravity lost, Then, 8.25 Spirit Indication is equivalent to 35.75 degrees of gravity.

Add extract gravity 1014:18

Original gravity 1049.93, showing a coincidence, which but rarely occurs, between the results of the two methods.

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It will be observed that in the latter method the determination of the « beer gravity” is an essential element, but this, owing to the frothiness of beer, can seldom be made with exactness ; hence arises the superior accuracy of the “ distillation process," in which the density of the beer is not necessary to be known, except as a check upon the results.

When cane-sugar is used to any extent in the brewing of beer, the preceding tables are not strictly applicable to the determination of original gravities, inasmuch as 95lbs. of pure cane sugar will produco as much alcohol as 100lbs. of starch sugar or the solid extract of malt wort; and as a solution of cane sugar increases several degrees in gravity before fermentation sets in-a point adverted to in the article on the manufacture of spirit,-it is evident that any given spirit indication obtained from a wort of that composition must represent fewer « degrees of gravity lost” than an equal indication from malt or grain wort. Accordingly, in experiments on sugar beers undertaken for private purposes, it is necessary, if abso. lute exactness be desired, to take the “ degrees of gravity lost ” from one of the following tables, although for the sake of simplicity, one general table, of which No. 2 above is a copy, is all that has been legalised, and the data of that table are, for the reason just assigned, in favour of the brewer who employs sugar.

In the determination, however, of the original gravity of distillers' wash brewed from cane-sugar, it should be borne in mind, that although the law only makes provision for the use of the table contained in the Appendix to the Act 23 & 24 Vict. c. 114, which is the same also as No. 2 above, it will be proper in such cases to consult the tables specially constructed for cane-sugar liquids, as below given.

TABLE No. 4.

To be used in the Distillation Process.

Degrees of Spirit Indication, with corresponding degrees of gravity lost in CANE-SUGAR liquids.

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To be used in the Evaporation Process. Degrees of Spirit Indication, with corresponding degrees of gravity lost in CANE-SUGAR liquida.

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In the construction of the tables now in use, 28 distinct quantities of wort prepared from various materials, were submitted to fermentation, and experimented on at frequent intervals during the continuance of each process. To illustrate the general mode of operating, it will be sufficient to give the particulars of an experiment on a solution of cane-sugar, which may be viewed as a wort of the simplest composition.

%

15? lbs. of refined sugar were dissolved in 10 gallons of water, making 102ths gallons of solution, the specific gravity of which was 1055-3 at 60°. After adding three fluid pounds of fresh porter yeast, the specific gravity was 1055.95 ; The original gravity, however, may be taken as 1055.3 (55.3 degrees.)

The wort in question was then set to ferment at a proper temperature, and as fermentation proceeded, samples were distilled, after periods of a few hours, and the density taken of the spirit and of the extract left after the removal of the spirit, when both liquids were made up with pure water to the bulk of wort operated on. The density of the partly fermented wort itself was also ascertained in each experiment, and in order to arrest the action of the yeast which would otherwise continue up to a certain point while the sample was being prepared for distillation, and thus vitiate the results, recourse was had to the following effectual expedient, originally suggested and adopted by Messrs. Dobson and Phillips.

A portion of the fermenting wort was removed from the bulk of the liquid, and introduced into a strong metal vessel, fitted with a steam-tight cover which screwed down on a washer of india-rubber. The lid being closed, heat was applied until the contents of the vessel rose rapidly in temperature up to 180°. It was found that the action of the yeast was completely checked when the wash was heated to this point. Then, the vessel, without being opened, was cooled to a temperature of 60°. By this arrangement none of the spirit generated in the wort was allowed to escape, and the wort itself was presented in a state that admitted of any observation being made upon it with perfect accuracy. The results of these experiments are shown in the subjoined table.

FERMENTATION OF CANE-SUGAR WORT OF THE ORIGINAL GRAVITY, 55.3.

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Columns III. and V., respectively, exhibit the spirit which has been produced and the solid matter which has disappeared-tbe first in the form of the specific gravity of the spirit expressed by the number of degrees it is lighter than water, or less than 1000; and the second by the fall in gravity of the solution of the solid matter remaining, below the original gravity 1055-3. This last value is termed “ degrees of gravity lost ;" it is always obtained by subtracting the extract gravity

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