Page:Encyclopædia Britannica, Ninth Edition, v. 4.djvu/319

Rh is long enough; stock ales should have half an hour or an hour extra. The finest pale ale is never boiled longer than one hour. Where it is necessary to have two boilings in one brewing, the second copper should boil rather longer than the first. The boiling during the first twenty minutes should be brisk, in order to break the wort.

Cooling.—When the wort has boiled the necessary time, it is turned into the hop-back to settle. The hop-back is a utensil made of wood or iron, and fitted with a false bottom of perforated plates ; these plates retain the hops in the back, whilst the wort is drawn off into the coolers. The wort should be allowed fifteen or twenty minutes to settle in the back, and when run on to the coolers should be thoroughly bright. In many breweries coolers are not used, the wort running direct from the hop-back through the refrigerator into the fermenting tun. When practicable this is an excellent plan, for worts often take harm whilst lying exposed on the coolers. In every brewery of any note the worts are cooled artificially by means of a refrigerator. Of these there are several kinds, but all are constructed upon the same principle, which is that of allowing a thin stream of wort to trickle over pipes containing a running stream of water. The water is either run direct from the mains or is pumped by an engine from a well. In every instance it is necessary that the water shall be several degrees colder than the heat the wort is to be "pitched" at, as brewers call it, in other words, the heat at which the wort is let down into the fermenting tun. This "pitching heat" varies very much. Beers pitched at high heats, say from 62° to 66°, come soonest into condition, but do not keep so well. Under ordinary circumstances 60° appears to be the best heat at which to start fermentation, or, in the case of strong ale, 58°.

Fermentation.—The fermenting tun may be round or square, open or closed, and made of wood or stone. Stone squares are universal in the northern counties of England, but are rarely met with in the southern and midland counties. When beer is fermented in a stone or slate square, it should never be pitched at a lower heat than 66° or 68°; for these utensils are very cold, and there fore liable to check or stop the fermentation. Every fermenting tun should be fitted with an attemperator. The attemperator consists of a series of pipes fixed within the tun, and having its inlet and outlet on the outside. It should be possible to run hot or cold water through these pipes at any hour, so that the temperature of the gyle can be raised or lowered at pleasure. The work performed by that natural process which we call fermentation is the conversion of saccharine matter into alcohol. It plays a most important part in the brewer's art, and deserves his most careful attention. In order to obtain a quick and regular fermentation, the brewer employs yeast, or barm, as it is called in some parts of the country. Great care must be taken that the yeast used shall be perfectly fresh and healthy, for it must never be forgotten, that it is impossible to obtain a good fermentation from bad yeast. Yeast that comes from porter should never be used in pale or delicately flavoured ales, as it is apt to impart a burnt taste and high colour. The quantity of yeast required depends upon the strength of the wort and the quality of the water. Strong worts require more yeast than weak ones ; and the same rule applies to hard waters as compared with soft. Worts of about 20 ℔ gravity should do well with 1 ℔ of yeast per barrel, whilst stronger worts require twice that quantity. As we have said, 60° seems to be the best heat at which to pitch wort, unless it is of a high gravity, or the fermenting tun be built in a very warm place, in which case the temperature of 58° will not be too low. The appearance of a gyle of beer during the earlier stages of a good fermentation is very beautiful. At first the whole surface is covered with a thick white foam, which, within a few hours, curls itself into every imaginable shape and form. This increases in height, until it presents the appearance of a number of jagged rocks of snowy whiteness. With these the artistic beauties of the fermentation disappear, although the fine thick head of yeast which follows delights the eye of the practised brewer, for it tells him that his fermentation is drawing towards a successful end. But the progress of the fermentation must not be judged by appearances alone. Samples should be taken from the tun at least twice a day, and weighed with the saccharometer. By this means the brewer tells at what speed the sugar is being converted into alcohol ; and when he considers the process has gone far enough, he stops it by taking away the yeast, which operation it; termed cleansing. At the end of the first twenty-four hours, the gyle should attenuate 1 ℔ in every three or four hours, whilst the temperature should rise from 1° to 2° during the same space of time. The fermentation may proceed quicker than this without any harm ensuing ; but if it does not reach the minimum speed of 1 ℔ in four hours, it may be said to be sluggish, and requires assisting. This is done by "rousing" the gyle every two hours with a utensil made for the purpose. Wort fermented in stone or slate squares must be roused every hour and a half, without exception. If unchecked the temperature of the gyle will rise to 76° or even 80°. Any heat above 72° is likely to affect the beer injuriously, for at that temperature the acetous fermentation commences. At the same time, beers for quick consumption may be allowed to rise a few degrees higher, and will perhaps be improved by the increase of temperature. The attemperator must be used to prevent the gyle reaching too high a heat.

Cleansing is the act of removing the yeast from the beer, in order to stop the fermentation. There are three modes of cleansing 1st, by simply skimming the yeast off as it rises to the surface ; 2d, by running the beer into casks, and then allowing the yeast to work out through the bung holes; and 3d, on what is called the Union, or Burton system, which is the second plan with some improvements. When beer is cleansed in the second or third mode, it is necessary to keep the casks or Unions full to the bung. They must, therefore, be refilled every two hours, either by hand or by a self-acting apparatus invented for the purpose. Brewers differ as to the time when the operation of cleansing should commence ; and, indeed, it is difficult to fix any Limit, as much depends upon the character of the ale and the appearance of the fermentation. In the writer s opinion strong ales, worked in casks or on the Burton system, should be cleansed when they have attenuated down to 12 or 14 ℔ ; weaker beers and pale ales should be allowed to go quite 2 ℔ lower before being cleansed. Stout and porter should be cleansed rather earlier than any kind of ale, in order that they may drink full in the month. When all the yeast has worked out of the beer, it is ready for the last process.

Racking and Storing.—Ales intended for quick con sumption should be racked so soon as clean, or they will be found flat and out of condition. A few of the finest hops should be put into the cask ; and in the case of pale ale the quantity should not be less than 1 ft) to the barrel. The finest strong and India paid ale should be stored between two and three months before being tapped, and even at that age, must be considered young. Ales intended to be stored some months should have a porous vent peg placed in the shive to keep the ale from fretting, and save the head of the cask from being blown out.