Page:The American Cyclopædia (1879) Volume III.djvu/268

 262 BREWING In the ordinary process of fermentation, in which the yeast rises to and remains at the sur- face, the gluten is not all rendered insoluble, but some of it remains in the beer, and on ex- posure to the air absorbs oxygen, and produces a ferment by which the remaining sugar is transformed into alcohol and carbonic acid, and the alcohol, again, into vinegar. The fermen- tation of Bavarian beer occupies a much longer time than that of common ale. The latter, as we have seen, occupies only six or eight days, while the other requires from four to six weeks, or even longer. The wort, which is prepared very much in the same manner as for other beers, is pumped from the hop back into the shal- low coolers in the upper story of the brewery, and is reduced, either in them or by afterward passing it over the refrigerator, to about 45 F., as speedily as possible. It then passes into the fermenting tuns, which are placed in cool rooms or cellars having a temperature of 40 to 45. The yeast is stirred into the wort, and in the course of two or three days the fermentation commences with the appearance of very minute bubbles of carbonic acid gas, which ascend and carry some of the yeast and the gluten to the surface, but do not retain it there ; for the glu- ten absorbs oxygen from the air, and the insolu- ble ferment Vhich it forms is deposited at the bottom of the tun as a viscous sediment, leav- ing the surface of the liquid exposed to the ac- tion of the air. The gluten is thus converted into yeast by atmospheric oxidation, and in time is entirely removed without the decomposition of all the sugar. Only as much has been trans- formed into alcohol and carbonic acid as it is desirable to have the beer contain. This kind of fermentation is called Uhterydhrimff, or bot- tom fermentation, and the yeast, which differs from common yeast, is called Unterhefe, or bottom yeast. Ordinary fermentation, in which the yeast forms upon the surface of the wort, is called Obergahrung,or top fermentation,and the yeast thus formed, Oberhefe, or top yeast, and, according to Liebig, is in a state of putrefaction, while bottom yeast is in a state of eremacau- sis, or decay. The precipitated yeast has not the capacity of exciting ordinary fermentation, but ordinary yeast may be employed in excit- ing slow fermentation at a low temperature, which causes a yeast to be deposited at the bottom which, by being used a few times, may be converted into the yeast of bottom fermen- tation. After the beer has been fermented sufficiently it is drawn off into large casks and allowed to lie for several months in cellars or cool rooms, which are kept at a temperature of between 40 and 45 F. A very slight fermen- tation and fining process here continues, until at last the beer is perfectly transparent and free from all fermentable matter. On account of this treatment it is called Lagerbier. Many of the modern lagerbier breweries now use enormous quantities of ice to cool the rooms in which the beer is fermented and stored. These rooms may be so constructed that the temper- ature can be perfectly controlled ; and as the air retains no more moisture than it does in u cellar, it being generally near the dew point in either case, the ice-cooled rooms are liked by those who use them, particularly as the brewing can be conveniently carried on dur- ing the summer months. Manufactured grape sugar is now used by many of the lagerbier brewers to furnish an excess of material for the production of alcohol, thus allowing a smaller percentage of gluten in the wort. As the gluten in the Bavarian process is the chief substance to be eliminated, this practice allows the fermentation to be completed in a shorter time than when malt only is used. When the grape sugar contains no acid or other objec- tionable matters, the practice results in econ- omy, but only on account of the saving of time, as the price of the manufactured sugar is fully equal to the cost of producing it in the wort from malt. Adulterations. A few years ago ale drinkers were alarmed by a report that strychnine was used in the manufacture of ale. Dr. Ure gives the following reasons for consid- ering this report groundless : "1. Strychnine is an exceedingly costly article. 2. It has a most unpleasant metallic bitter taste. 3. It is a noto- rious poison, and its use in any brewery would ruin the reputation of the brewer. 4. It can- not be introduced into an ordinary beer brewed with hops, because it is entirely precipitated by infusions of that wholesome, fragrant herb. In fact, the quercitannic acid of hops is incom- patible with strychnia and all its kindred alka- loids. Hence, hopped beer becomes in this respect a sanatory beverage, refusing to take up a particle of strychnia, and other noxious drugs of a like character." Mr. Herepath has given a test for the detection of picrotoxine, the active principle of the eoceulus Indicia, which is based upon the property possessed by char- coal of separating it from its aqueous solution. An excess of acetate of lead is added to the beer to throw down the lupuline and other ex- tractive matters, the excess of lead in the fil- trate removed by sulphuretted hydrogen, and the excess of this gas removed by boiling. The solution is then evaporated to a sirup, and agi- tated with animal charcoal, which will absorb any picrotoxine that may be present. On cool- ing, the charcoal is collected on a filter, washed with a small quantity of water, and dried at 212 F. The charcoal is then boiled in pure alcohol, which being filtered will upon evapo- ration yield crystals of picrotoxine if the beer was adulterate'd with it. If the evaporation is slowly and carefully conducted, the picrotox- ine will separate in well defined quadrilateral prisms, sometimes in needles, and, when the evaporation has been rapid, in beautiful plu- mose tufts. Picrotoxine is inodorous, intensely bitter, and neutral to vegetable colors ; dis- solves in 150 parts of cold, in 25 parts of boil- ing water, and in 3 parts of boiling alcohol of specific gravity 0.800. Picric acid, which is said to be used in the adulteration of beer, may