The wort, after receiving in the mash tun the extract of fermentable matter from the malt, requires to be boiled with the hops, that it may imbibe the essential oil of those plants. Another object of the boiling is, to coagulate the excess of mucilage which is unavoida bly extracted from the malt in =shim, for if this were suffered to remain in solution in the beer, it would ne ver become fine, but would always be cloudy, in spite of the most powerful precipitants. The boiling hardens this mucilage in the same manner, probably, as the white of an egg acquires solidity by boiling ; and for the same reason, perhaps, as albumen is one of the constituent parts of malt; the boiling curdles the muci lage, before suspended, and equally dispersed through the wort into the distinct fecula, leaving the fluid be tween them clear and transparent. These fecula arc af terwards deposited in the coolers, thrown out in the form of yeast in fermenting, and, lastly, in the Ices of the beer, thus freeing it from matters which would otherwise have remained in solution. The heat which is given is that of boiling. In an open copper a greater heat than this cannot be given; but in the close copper, the heat is somewhat increased, by forming steam of sufficient elastic force to raise a column of water, of the depth of the pan. A considerable quantity of water is boiled off in steam, which tends to concentrate the wort, and render it stronger. It is by the quantity thus evaporated that some brewers form their judgment of the wort being sufficiently boiled. Others draw their conclusion from the transparency of the wort, or from its containing fecula. This is called breaking of the wort, or curdling. The duration of the boiling is very various among different brewers. It must always be continued till the breaking appears ; and perhaps a much longer continuance of the boiling is injurious, for the fecula or flakes of coagulated matter are observed to become larger, the longer the process continues; and from an experiment of Mr Combrune, it appears, that, if these flakes arc collected, and boiled in water, the extract will ferment, and yield a viscous liquor. Hence they contain a portion of the fermentable matter, and therefore should not be separated by boiling, farther than is necessary, reserving the minute separation of such matters from the beer to be effected by the fer mentation, in the form of yeast and lees.
Thus boiling the wort too short a time, leaves in it more of the gross parts of the extract of the malt than can be thrown out by the fermentation; and at the same time the lime of the hops will not be sufficiently ex tracted. On the other hand, too much boiling causes a waste of fermentable matter, by producing more fe cula than is necessary for the former condition; and the hops, by being boiled too much, after having given out their agreeable essential oil, communicate a gross bit ter oil, which is unfavourable to a sufficient fermenta tion for producing the requisite spirit in the beer. It will readily be seen, that the medium cannot be attain ed, without attending to the circumstances of the pre vious process of the mashing, and the nature of the malt, and also to the quantity and quality of the hops, and the length of beer drawn, that is, the quantity of beer intended to be produced from a certain quantity of malt. The greater the portion of the farinaceous mat
ter which has been extracted from the malt, the longer boiling will be necessary to curdle it. This will hap pen from malt imperfectly made, or from too low heat for the mashing. The first wort is generally boiled a much shorter time than the succeeding one, that the hops may not be so much impaired at the first, but that they may yield sufficient oil to the second and thirct worts. One hour for the first wort, two for the second, and four for the third wort, are recommended for beers, which are intended to be kept twelve months, having a large proportion of hops, that is 121b. to the wort pro duced by one quarter of malt, and which is intended to be fermented at about 40 degrees of temperature. For small beer only half an hour is necessary for the first wort; one hour for the second ; and two hours for the third. The quantities to be evaporated during the boiling are equally various for different kinds of beer ; and therefore we cannot say any thing of it in this place, further than that its extremes are from 5th the quantity of wort to Hops contain a fine essential oil, which has an agree able bitter flavour. They are requisite to preserve the beer from the acetic fermentation, which would other wise take place immediately after the spirituous fer mentation ceases. The addition of the hops checks the disposition to ferment in such a degree, that the beer may be kept a sufficient time in a state of slow fermentation, to acquire strength and spirit, and to pre cipitate the farinaceous matter suspended in it, without becoming sour. On this account, the quantity of hops which are put to the beer, depends upon the length of time it is intended to be kept before it is drunk, on the length drawn, and also on the heat at which the beer is intended to be set to work in the gyle tun. The hops are put in the copper and boiled with the first wort, and are again used to boil with the succeeding worts. The quantity is as various as the different kinds of beer. Twelve pounds to the porter produced from 1 quarter of malt is judged sufficient to preserve such beer for 12 months, when fermented at 40 degrees ; but, in the heat of 60 degrees, double the quantity of hops will scarcely preserve the beer during the same time. For small beer to be fermented at 40 degrees, Sib. to the quarter will be sufficient; but at 60 degrees, it will re quire 6 lb. of new hops, or 61 lb. of old hops, which are such as have been kept one year, and have, in conse quence of this, lost sonic of their good qualities; but this difference is not worthy of notice, when only small quantities are used. It ought to be observed, that small beer is not generally intended for keeping any consider able length of time. Some breweries, from the great space necessary to store their hops, have in some sea sons, when they required a great stock, adopted a me thod of pressing the bags in a strong press to about their original space, and confining them in this state by cords ; a process which is thought to preserve them better than if they were unconfined.