Page:A Practical Treatise on Brewing (4th ed.).djvu/107

Rh that period, than can possibly be the case in a process of from forty to seventy hours, or even sometimes shorter.

It will always be found also, that beers having undergone a healthy and not too vigorous fermentation, will acquire fulness from age; while on the contrary, those undergoing a long fermentation lose their fulness, and very often become sour.

Many brewers are in the practice of using yeast by measure. This is a very uncertain mode of procedure, as yeast will vary in weight many pounds per gallon. The surest and best mode of applying yeast is by weight, and when we are not thoroughly acquainted with its quality, it should always be mixed with a small portion of worts at a temperature of from 80° to 90°; and should be seen rising in whatever vessel it may have been mixed, before it is added to the worts in the fermenting tun.

When worts are got together in the gyle-tun at a temperature under 60° F., about 1 lb. of yeast to 10 lbs. gravity per Long’s instrument, will be found to produce a loss of 1 lb. in attenuation, for every degree gained in heat. This is a good working rule. When the fermentation (from unsoundness in the worts or other causes) does not go on regularly, the beer is apt to get yeast-bitten; and the quantity of yeast used, is blamed as the cause. This evil, however, more frequently arises from too