66 BULLETIN 983, U. S. DEPARTMENT OE AGRICULTUEE. 



size of the material that is to be cooked, as, for instance, sawdust will 

 extract more readily than larger material. As the sugars are readily 

 soluble, only a short extraction period is necessary — that is, from 5 to 

 10 minutes on each cell — making a total extraction period of 50 to 75 

 minutes. This period, however, will be governed in part by the 

 length of time that it takes the water to drain through each cell, and 

 this in turn depends on the size of the cell. 



The cells should not be too large, else the extracting water will not 

 pass through the material easily, and there will be a tendency to 

 channel. The amount of water used should be such as to make the 

 resulting acid extract 11° to 12° Brix, the proper concentration for 

 fermentation. The Brix will rise another degree on neutralization. 



As in laboratory work, so in regular practice, a large number of 

 extractions or washings with small amounts of liquid will give a 

 better extraction or a more thorough washing with a more concen- 

 trated extract than will fewer extractions with larger amounts of 

 water for each extraction. 



NEUTRALIZATION AND SETTLING. 



After extraction the acid extract is nearly neutralized with lime 

 or a high-grade limestone. For this purpose a magnesia stone is 

 undesirable. For a number of reasons it has been found preferable 

 to cool the acid juice to 100° F. or less before it is neutralized. During 

 neutralization the temperature will rise a few degrees. The extract 

 is then allowed to stand and settle out the sludge of calcium sulphate. 

 As this usually requires from 15 to 18 hours, adequate tank capacity 

 is required. 



COOLERS. 



The clear juice is then drawn off and passed through coolers to 

 reduce its temperature to from 80° to 90° F., after which it goes into 

 the fermenting tanks. The coolers should be of copper, and their 

 size will depend upon the temperature of the water supply available. 

 As the calcium sulphate in the neutral juice will partially crystallize 

 out during the cooling, the coolers should be so designed as to be 

 easily taken apart and cleaned. 



FERMENTATION, DISTILLATION, ETC. 



A 96-hour fermentation period is permitted; hence a 4-day fer- 

 menter capacity is required. The size of the individual fermenter 

 will be determined largely by the outdoor mean temperature and 

 other local conditions. The other apparatus is the standard distillery 

 equipment in use in grain and molasses distilleries. 



