Mr Long, in his patent dated 1790, has recommended the hops to be boiled or macerated in water, sufficient to CONTI' them for 10 hours ; at which time, the heat (in creased by degrees from the beginning,) is to be only 175°. This gradually increasing heat is to be continued 4 hours longer, and made to boil slowly for the last ten minutes: the extract thus produced is to be let on through a cooler or worm pipe, into the gyle tun, where it is to he mixed with the first wort, which has been boiled a very short time without hops. The hops are to be boiled again twice, in order to make extracts for the second and third worts.
This operation is performed by spreading out the boiling wort in a thin sheet exposed to the action of the air, that it may be brought to the proper heat for work ing or fermenting. It is a great object, that the cooling should be performed as expeditiously as possible ; for the taint of foxing, before mentioned, is otherwise in danger of overtaking the beer in this process, if it con tinues as much as 12 hours. The wort, therclore, should be laid at such a depth in the coolers, that they will cool it in about 7 or 8 hours to the temperature of near ly 60 degrees, which, generally speaking, is about the average temperature for pitching or setting to work. To effect this, the wort in summer should not be laid at a greater depth than one, two, or three inches; but in winter, it may be as deep as 5 inches. In the hot sum mer months the worts must be got as cold as the wea ther will permit ; and it is found that the coldest period of the 24 hours is about 3 o'clock in the morning, at which time, therefore, they should be set to work. In the winter they may be let down at any hour when they arrive at the proper temperature.
The wort should not be suffered to remain in the coolers after they are sufficiently cold, or a slow fer mentation may commence, from the sediment left in the cooler by a former process This, which is called set ting the backs, is very prejudicial.
Of Fermentation in the Gyle Tun.
From this process, the beer obtains its strength and spirit, by converting the sugar extracted from the malt, into alcohol and spirit, and separating the redundant part of the mucilage in the forms of yeast and lees. In this process, an immense quantity of carbonic acid gas, or fixed air, is given out from all parts of the fluid. During fermentation, the constituent parts of the wort arc at first decomposed, and afterwards a recomposition takes place in a new order, causing the change above mentioned. The sweet taste of the wort disappears; it loses its viscidity, from the separation of mucilage and gluten, which takes place ; its specific gravity is consi derably diminished ; and a spirituous and inebriating quality is given to the liquor. When the wort is let down at the proper temperature from the coolers, into the gyle tun or square, a requisite proportion of yeast is added to it, and in a short time the fermentation com mences. Its first appearance is a white line or border on the surface of the liquor, commencing at the sides of the tun, and gradually advancing into the middle, till the whole surface is covered over with a white scum, form ed of very minute bubbles of gas, which increase in size as the fermentation advances, and cot er the liquor to a depth of several inches with a froth of yeast. The tem perature of the fluid increases considerably ; and during all this time, the rising of the bubbles of gas, causes an incessant sound and a great agitation of the fluid. Part
of the bubbles burst as they arrive at the surface, and the film of yeast which enveloped them sinks, until it is borne up again by the ascending i ubbles. These films form at first a yellow, and, as the process advances, is brown dirty covering to the head of yeast, giving it the appearance of rocks. In this state the fermentation is considered as at its crisis, and afterwards diminishes. The yeast, which was at first a thin watery substance, quickly melting down into a fluid, has now become vis cid and tenacious, which is the cause of the increased size of the bubbles, as they will hear greater distension without bursting. When the head begins to sink, which it does, first in the middle of the tun, the fermentation is to be checked by cleansing, that is, dividing it into small casks, and allowing any farther yeast which it may pro duce, to flow off as fast as it is formed. The proper management of the fermentation intimately depends upon the temperature to which the wort is cooled, when the yeast is put to it. The violence of the fermentation is increased with the heat ; and if this is too great, the pro cess advances so quick, as not to be readily checked when at its proper stage, but will go on to produce the acetic fermentation either wholly or partially, before it has sufficiently precipitated the mucilage, or. in the lan guage of the brewer, purged itself, and consequently it has an unpalatable mixture of acid from the excessive fermentation, and of bitter from the redundant mucilage. In the other excess, that is, too low a heat for the fer mentation, the decomposition of the wort takes place ; but this, not being succeeded by the proper reunion of the parts, produces an unpalatable half fermented liquor, containing a combination of sweet spirit and bitter, and sometimes an approach to putridity. The medium is to be sought for between 80 and 40 degrees of the thermo meter; the exact temperature varying with the circum stances of the preceding operations, the temperature of the atmosphere, and the liquor which is intended to be produced. In some of these (as in strong pale ales,) the object of the brewer is to form a beer of the greatest possible strength and spirit, very clear and fluid, of a fine light colour, without containing much of the vegetable fla vour. Such liquor approaches to wine. In the other extreme, as brown ales and porter, a fullness of palate, deep colour, glutinous taste, and vegetable flavour, are produced, by retaining part of the farinaceous matter, and giving to it an agreeable taste by the fermentation, rather than expelling it totally, as in the first instance. In making the required varieties, in the manner of the fermentation, to meet these intentions of the brewer, the quantity and quality of the yeast employed, as well as the temperature, must be considered. 'Tit yeast pro duced from the fermentation of strong beer is the most proper to effect that temperate and regular fcrnient-tion of the beer, which is described ; perhaps. from the tenacity of its substance, it does not so suddenly com municate the gas it contains to the fluid which it is in tended to put in fermentation. The yeast of weak small beers should not be used, when the other can be procured ; for, though its fermentable powers are slight, it is apt to act violently for a short time, and then cease, probably from the thin light mucilage. of which the gas bubbles are formed, bursting as soon as they are put in, and communicating their contents to the wort.