| Having therefore a fallacious gravity of | 828 |
| Deduct 10 per cent. | 85 |
| Real gravity to go into gyle-tun | 743 |
As we intend to make the beer 42 lbs. gravity per barrel, we must now find out what number of barrels of 42 lbs. can be produced from 743; divide, therefore, by 42 the required strength, which will leave 17 barrels and three firkins. Having thus ascertained that we shall have about 18 barrels of ale, now throw the necessary quantity of hops into the copper, calculating by so many lbs. per barrel: this may be 4, 5 or 6 lbs. per barrel, or even more, according to the public taste, and the length of time the beer is intended to be kept. For beer of this gravity, however, there should never be less than from 4 to 5 lbs. per barrel: we shall here take 4½ lbs., which will be 81 lbs.
We have next to calculate what number of barrels must be turned out of the copper so as to have about 18 barrels in the gyle-tun. There are now in the copper, with the addition of the hops, about 24½ barrels. The hops will retain nearly one barrel and a-half, and rather more than two barrels will be evaporated on the coolers, in all 3½ barrels; add, therefore, 3½ to 18, which makes 21½. Three barrels, therefore, must be evaporated in boiling, leaving 21½ to be turned into the coolers.
We must now return to the brewing which we
