Page:A Practical Treatise on Brewing (4th ed.).djvu/85

Rh opinion may have arisen from a mistake in calculating the difference of the extract as shown by the taps, between these taps, and the actual gravity of the boiled worts in the gyle-tun—or the difference, as some call it, between the raw and boiled gravities. An erroneous method of calculating the extract per quarter is followed by some brewers, who value the gravity of the worts as they ﬂow from the mash-tun, instead of taking the gravity of the worts from the coolers as they go into the fermenting tun; thus showing a disparity of from 10 to even 20 per cent. more than the malt actually produces. We shall, however, be able to show, when we afterwards treat of extracts, that both gravities, if properly taken, must be precisely the same, only deducting for the quantity retained by the hops in the different boilings, which is afterwards transferred from one wort to the other in regular progression, so as ultimately to leave in the hops only a very trifling portion of the extract.

There is also a difference of opinion as to the use of open and dome coppers. For fine pale ale, there can be very little doubt that open coppers are preferable, although dome-coppers, (where a free evaporation of steam is allowed without much pressure) can do little harm. It is to be recollected, however, that in proportion to the perpendicular column of worts in the copper, and also to their greater specific gravity, charring will take place.