114
BEER.'
upon the -whole cf the goods. The percolating wort is allowed to flow off, hy three ormore small stopcocks round the circumference of the mash-tun, to ensure the equal dif-fusion of the liquor.
The first sparge being run off in the course of twenty minutes, another similar oneis affused ; and thus in succession till the whole of the drainage, when mixed with thefirst mash-wort, constitutes the density adapted to the quality of the ale. Thus, thestrong worts are prepared, and the malt is exhausted either for table beer, or for areturn, as pointed out above. The last sparges aie made 5° or 6° cooler than the•first.
The quantity of hops seldom exceeds four pounds to the quarter of malt. The mannerof boiling the worts is the same as that above described; but the conduct of the fer-mentation is peculiar. The heat is pitched at 50°, and the fermentation continues froma fortnight to three weeks. Were three brewings made in the week, seven or eightworking tuns would thus be in constant action ; and, as they are usually in one room,and some of them at an elevation of temperature of 15°, the apartment must be pro-pitious to fermentation, however low its heat may be at the commencement. No moreyeast is used than is indispensable; if a little more be needed, it is made effective byrousing up the tuns twice a day from the bottom.
When the progress of the attenuation becomes so slack as not to exceed half a poundin the day, it is prudent to cleanse, otherwise the top-barm might re-enter the body of thebeer, and it would become yeast-bitten. When the ale is -cleansed, the head, which hasnot been disturbed for some days, is allowed to float on the surface till the whole of thethen pure ale is drawn off' into the casks. This top is regarded as a sufficient preservativeagainst the contact of the atmosphere. The Scotch do not skim their tuns, as the Lon-don ale brewers commonly do. The Scotch ale, when so cleansed, does not require tobe set upon close stillions. It throws off' little or no yeast, because the fermentationwas nearly finished in the tun. The strength of the best Scotch ale ranges between 32and 44 pounds to the barrel; or it has a specific gravity of from 1-088 to 1-122, accordingto the price at which it is sold. In a good fermentation, seldom more than a fourth ofthe original gravity of the wort remains at the period of the cleansing. Between onethird and one fourth is the usual degree of attenuation. Scotch ale soon becomes fine,and is seldom racked for the home market. The following table will show the progressof fermentation in a brewing of good Scotch ale:
20 barrels of mash-worts of 42§ pounds gravity = 860-620 — returns 6~L = 122
12 ) 982-6
pounds weight of extract per quarter of malt = 81
Fermentation:—
March 24. pitched the tun at 51°: yeast 4 gallons.
Temp.
Gravity.
25.
52°
41 pounds.
28.
56°
39
30.
60°
34
1.
62°
32
4.
65°
29 added 1 lb. of
5.
66°
.25
6.
67°
23
7.
67°
20
8.
66°
18
9.
66°
15
10.
64°
14-5 cleansed. *
The following table shows the origin and the result of fermentation, in a number ofpractical experiments:—
Original Gravity of- the Worts.
Il)s. per Barrel ofSaccharine Matter.
Specific Gravity ofthe Ale.
Lbs. per Barrel ofSaccharine Matter.
—
Attenuation, or Sao-eharum decomposed.
1-0950
88-75
1-0500
40-25
0-478
1-0918
85-62
1-0420
38-42
0-552
1-0829
78-125
1-0205
16-87
0-787
1-0862
80-625
1-0236
20-00
0-757
1-0780
73-75
1-0280
24-25
0-698
1-0700
65-00
1-0285
25-00
0-615
1-1002
93-75
1-0400
36-25
0-613
* BkEWINQ (Society for diffusing Useful Knowlsdge), p. 156.