388 FIELD CROPS FOR THE COTTON^BELT 



certain impurities and cause them to rise, to the top, 

 whence they are skimmed off. (3) Adding 10 pounds of 

 dry, fine yellow clay to every 50 gallons of juice. The 

 particles of clay, on settling to the bottom carry with ttiem 

 much of the suspended impurities. (4) Filtering the juice. 

 (5) The additit)n of a small amount of milk, which coagu- 

 lates and rises to the surface wheh the juice is heated 

 bringing with it a certain class of impurities. (5) When 

 the juice is somewhat acid, a small amoimt of lime is 

 added to the heated juice. 



Skimming, settling and claying are the means most 

 commonly used for clarifying the juice. 



The juice is finally evaporated in large shallow pans. 

 These pans are divided off into compartments and the 

 boiUng juice is made to flow from one compartment to 

 another at such a rate as to concentrate it into sirup by 

 the time the outflow is reached. 



482. Yield. — Soils of average fertility should produce' 

 from 8 to 10 tons of green sorghum. The amount of jliice 

 extracted from a ton of cane will vary with the kind of mill 

 used and the quality of the cane. With the better grade 

 of mills from 800 to 1200 poimds of juice should be secured 

 from a ton of canes. This should yield from 15 to 30 

 gallons of sirup. The sugar content of cane juice varies 

 from 8 to 15 per cent. 



483. Enemies. — Two smuts affect the sweet sor- 

 ghums, viz., the grain smut (Phacelotheca diplospora) and 

 the whole-head smut (P. reiliana). The damage from 

 these diseases is usually light. Both can be partially 

 checked by crop rotation and care in selecting planting 

 seed. The grain smut can be controlled by the hot-water 

 treatment or the formalin treatment as outUned for oat 

 smut, page 339. 



