Page:A Practical Treatise on Brewing (4th ed.).djvu/194

178 mean time, should be again charged up with liquor, and brought to the proper temperature for going on with the after mashings. The mash having stood its time, let the worts now run from the mash-tun into the under-back. The average heat of the tap should be 148° to 152°; they should drain off in about 45 minutes, and there should be from 45 to 47 barrels at 35 or 36 lbs. gravity, per Long’s instrument.

Get 23 barrels of this first tap into the little copper for ale to be made 42 lbs. per barrel, and immediately afterwards get the remaining 24 barrels into the large wort-copper, at the same time throwing in a few hops. On trying a sample of the worts, we find they weigh 36 lbs. gravity.

If you multiply, therefore, 36, the lbs. gravity per barrel, by 23, the number of barrels in the copper, it will give 828. This, however, is the aggregate gravity as calculated when reduced to a temperature of 60°, without making any allowance for evaporation and condensation. The late Mr. Richardson, of Hull, has given accurate calculations for the necessary deductions to be made; but as we find that by deducting 10 per cent. we come near enough the truth for practice, and have also less trouble, this mode, which also makes allowance for the quantity retained by the hops, has been adopted.