In making calculations for regulating the gravities per barrel of the different beers to be brewed, it will generally be found that by deducting ten per cent. from the apparent gravity of the taps, as shown by the instrument at a temperature of 60°, we shall come very near the truth, at least near enough for practice. Should extra quantities of hops be used, allowance must be made accordingly. This, however, is only for the first worts. Every 60 lbs. weight of hops retains nearly a barrel of worts of the same gravity as those turned out of the copper. For the second worts, therefore, after deducting the ten per cent., add the gravity of one barrel of the first worts for every 60 lbs. of hops used in the first boiling. This in the second boiling will be replaced by nearly an equal quantity of worts, of the same gravity as turned out of the copper, which, in making the calculation, is to be deducted from the aggregate of the second worts, and so on with a third wort if necessary.
Having thus made accurate calculations of the actual number of pounds gravity we have in the gyle-tun, the aggregate amount of pounds gravity is to be divided by the number of pounds gravity per barrel the beer is intended to be made; the quotient is the number of barrels at said gravity, which can be produced. All we have now to do is to turn out of the copper such a number of barrels as will make up our calculated quantity in the
