The gallon, by which malt is measured, though less, is nearly of the same capacity with that, which is used for beer or water. The quarter of malt, contains 64 gallons of this measure, and the barrel, within the bills of mortality, according to the gauges used by the excise, contains 36 gallons, but without the bills, 34; though the first quantity is the measure for sale throughout the kingdom. Hence it would appear, that proportioning the grain to the barrel of water would be no difficult undertaking. This however is so far from being the case, that, after having made use of several calculations to help us to the true proportions, we shall find, they want the corroborating proofs of actual experience, to be entirely depended upon.
The ultimate parts of water are so very small, as to make this, as well as all other liquids, appear to the eye one continued uniform body, without any interstices. This cannot be said of malt laying together either whole or ground; there are numbers of vacancies between the corns, when whole, and between the particles when ground, but for our present purpose the volume occupied by any quantity of malt is properly no more, than the space which would be occupied by every individual corn, either whole or cut asunder, were they as closely joined together as water.
To determine, with precision, the quantity of cold water to be added to that, which is brought to the boiling point, (an act by the brewers called cooling in) it is necessary to know, what proportion a quarter of malt bears to the measure of a barrel of water. Several operations will be found requisite to come to this knowledge; viz. to take several gauges of different brewings, more especially in the first part of the process; to be well acquainted with the degree of dryness of the malt used, the heat of the first extract, and the quantity of liquor the mash tun holds upon every inch; to find out what degrees of expansion are produced by the different degrees of heat in the first mash, how much less water the mash tun holds upon an inch when hot, than it does when cold, what quantity of water is lost by evaporation, and in what proportion at the several terms of the process. In order to put this in practice, the gauges of the following brewings were taken.
5 quarters of malt dried to 125 degrees.
| B[28]. F. G. | ||
| The quantity of water used for the first mash was set | } | 12 2 3 |
| The malt and water gauged together in the mash tun just before the tap was set | } | 25, 00 inches. |
| Allowance for the space under the falsebottom boards of the mash tun, as near as could be computed | } | 0, 66 inches. |
| The goods gauged in the mash tun, afterthe first tap was spent | } | 15, 41 inches. |
| B. F. G. | ||
| First piece gauged in the copper | 8 0 2 | |
| ——————————— | ||
| B. F. G. | ||
| The water employed for the second mash was | } | 12 2 3 |
| The grist gauged with this water just before the tap was set | } | 30, 62 inches. |
| And just after the tap was spent | 15, 63 inches. | |
| B. F. G. | ||
| The first wort consisting of these two pieces gauged in the copper | } | 21 2 0 |
| ——————————— | ||
| B. F. G. | ||
| The water used for the third mash was | 8 3 6 | |
| Just before the tap was set the grist with this gauged in the mash tun | } | 24, 60 inches |
| And just after the tap was spent | 15, 20 inches. | |
| ——————————— | ||
| B. F. G. | ||
| The water used for the fourth mash was | 8 3 6 | |
| The mash gauged just before the tap was set | } | 24, 60 inches. |
| And just after the tap was spent | 15, 16 inches. | |
The heat of the first extract was 136 degrees, to which adding two degrees, for what is lost by the tap spending, the true heat of the mash is 138 degrees.
The first extract, before it is blended with hops, may be estimated to be nearly as strong as a first wort of common small beer. This, when under a strong ebullition, raised the thermometer to 216 degrees, and seven barrels of such a wort, when boiling, occupied an equal space with nine barrels of cold water, at the mean temperature of 60 degrees. Now, if the degrees of expansion follow the proportion of those of heat, the following table, constructed upon this supposition, will shew how many barrels of cold water would be necessary to occupy the same space with seven barrels of wort of different heats.
| Degrees of heat. | Barrels of cold water. | Barrels of wort. |
| 216 | 9,00 | 7 |
| 206 | 8,87 | 7 |
| 196 | 8,75 | 7 |
| 186 | 8,62 | 7 |
| 177 | 8,50 | 7 |
| 167 | 8,37 | 7 |
| 158 | 8,25 | 7 |
| 148 | 8,12 | 7 |
| 138 | 8,00 | 7 |
| 127 | 7,87 | 7 |
| 119 | 7,75 | 7 |
The quantity of water evaporated in a brewing, when not in immediate contact with fire, is more considerable than it is generally apprehended to be; after repeated trials, I have found that what was lost in this manner amounted nearly to one fifth.