of sugar, the continued generation of carbon-dioxide keeping the lighter particles in suspension.

ROTTEN FERMENTATION.

This manifests itself by a foul odor arising from the fermentation, which is best observed by blowing into the Kräusen head. Cause: Infection by bacteria of putrefaction. (See "Contaminations of Yeast.") For treatment see Bacteria Turbidity. ROPY FERMENTATION.

In top fermenting beers. The beer becomes stringy or ropy. Cause: Infection, usually by bacillus viscosus.

VACUUM FERMENTATION SYSTEM.

The important features of this system are:

1. The fermentation is conducted in closed glass enameled steel tanks, avoiding necessity of varnishing.

2. There is no contact with the atmosphere.

3. Sterilized air only is admitted, under perfect regulation during the fermentation.

4. Fermentation being conducted under a partial vacuum, there is a continuous removal of carbonic acid gas as fast as generated, which, together with admission of sterilized air, causes a continuous rousing of the beer.

5. The fermentation is completed within seven days from the kettle.

VACUUM FERMENTATION PLANT AND FITTINGS.

The special apparatus used in the vacuum fermentation system are as follows (see illustration):

1. Beer inlet with cap.-2. Pipe support for three-way fixture. -3. Gate valves for attemperator connections.-4. Air filter.-5. Air sight feed with glass.-6. Air check and stop cock.-7. Racking cock with strainer (formerly called spring racking valve).— 8. Racking-off cock with cap and chain with half-inch air pipe connection.-9. Bracket for yeast valve support.-10. Manhole cover.-11. Beer outlet for bottom elbow.-12. Yeast strainer.— 13. Top or large ear for manhole crab.-14. Bottom or small ear for manhole crab.-15. Crab, wheel and screw for manhole plate -16. Testing cock with rubber nipple.-17. Thermometer. -18. Air cock with elbow for hose connection.-19. Three-way fixture for vacuum, gas and air connections.-20. Top cask connection. The half-inch valve in the air pipe just above the air sight feed fixture is not shown in the marginal fittings, nor is the testing glass (bottle), used on testing cock.

The dimensions of the tanks are as follows:

Inside diameter of all tanks, 7 feet 6 inches.-Outside diameter of all tanks, 8 feet.-Dish of tops and bottoms, 10 inches.— Height of each ring, 30 inches.-Height of legs, 18 inches.-Bottom of tank above floor, 7 inches.-Height of tank over all, three rings, 10 feet 2 inches.-Height of tank over all, four rings, 12 feet 6 inches.-Height of tank over all, five rings, 15 feet 3 inches.

The capacity of tanks is as follows:

Three-ring tanks hold full 85 barrels.-Four-ring tanks hold full 110 barrels.-Five-ring tanks hold full 135 barrels.

The following cellar space is required:

As far as refrigeration is concerned, it will then require icenrachine capacity over the cooler to 7° to 71% R., for cooling the vacuum cellar 22,000 cubic feet at 6° R., for cooling the beer, say, to 1° R., and for cooling the racking-room as usual. Estimates by experts place the ice-machine capacity required, complete, at thirty tons for such a plant.

The chip tanks and carbonating tanks are the same as the vacuum tanks, except that they are made of heavier steel and reinforced to stand excessive pressure. The fittings of these tanks are also of bronze, and specially adapted to their purpose. These tanks are steel, glass enameled.

FERMENTATION.

The preparation of the wort is identical with the method employed for wort intended for open fermentation. The wort is cooled to 46° to 49° F. (61⁄2° to 712 R.), and run into the starting tub or directly into fermenting tank. Yeast is added as soon as cooling is commenced, and the quantity is 3 per cent of the total extract in wort in pounds, or about 4 to 1 pound per barrel. The temperature of the fermenting cellar is 43° to 48° F. (5° to 7° R.). If the wort has been run into an ordinary starting-tub, it is run or drawn by vacuum into the fermenter as soon is the Kräusen appear, generally in 12 to 16 hours. If the wort

has been run into the fermenter directly from the cooler it need not be drawn into another fermenter until the final stage of fermentation. The fermentation may also be finished in one fermenter only, if desired. When the beer has been collected in the fermenter, the vacuum is regulated to 15 to 18 inches, and this is maintained during the fermentation. The amount of filtered air desired to be passed through the fermentation can be exactly regulated and observed. The amount of air and the time for which it is to be admitted depend upon various conditions. The general practice is to admit the filtered air as soon as 15 to 18 inches of vacuum has been reached in the fermenter. The admission of air is continued generally for 48 to 96 hours. The temperature of the fermentation is allowed to rise to 51° to 53° F. (81⁄2° to 91⁄2° R.), depending on conditions and results desired. When about 90 to 95 per cent of the final apparent attenuation has been reached, lowering of the temperature is proceeded with in the usual way. The vacuum is maintained until the saccharometer indications remain stationary for six hours, when the vacuum is relieved by allowing filtered air to enter at the top of the fermenter. The fermented beer is allowed to rest from 24 to 48 hours, for the yeast to settle out, and for cooling to the desired temperature before running into the chip-casks, which is generally 36° to 39° F. (2° to 3° R.).

SAMPLE FERMENTATION.

1st Obser- 20 3d 4th 5th Obser- 6th 7th vation. Obs. Obs. Obs vation. Obs. Obs.

The treatment on chips is identical with that now in ordinary practice for stored beer. If the beer is intended for carbonating, it is cooled to 33° to 32° F. (1⁄2° to o° R.), and this temperature maintained for 48 to 96 hours, depending upon the composition of the beer and the character of the yeast that has been em

ployed in its fermentation. After being held at so low a tcmperature for the necessary time, it is filtered. Care must be taken that the temperature does not rise during filtration. The filtered beer is then forced through the carbonator and charged with the gas collected during the fermentation, and is then stored for 12 to 24 hours in a cask under pressure, and then racked off.

COLLECTING CARBONIC ACID DURING THE FERMENTATION. About 12 to 24 hours before starting to collect gas the air is shut off, but the vacuum kept on. The vacuum-pump conveys the gas to a small cylinder. When the gas pressure in this cyiinder reaches about 3 to 4 pounds, this pressure opens the steam valve to the compression pump. This pump forces the gas into steel cylinders to a pressure of 150 pounds, or more, if desired. If the gas pressure in the small cylinder falls below 3 pounds the steam valve on compression pump closes. In this way the gas collection works quite automatically.

CARBONATING.

The desired gas pressure in the carbonator, generally 23 to 25 pounds, is regulated by a reducing valve between the gas storage tanks. The back pressure on the carbonated beer is generally about 15 pounds. Of course, the pressures vary according to the desired quantity of carbonic acid gas the carbonated beer is to contain.