4 BULLETIN 570, U. S. DEPARTMENT OF AGRICULTURE. 



rounded by a sieve mantel oi heavy iron wire. The rice is fed from 

 the top and is rubbed thoroughly between the cone and the sieve 

 before passing out at the bottom. The severity of the scouring 

 may be varied by raising or lowering the cone, thus decreasing or 

 increasing its distance from the wire screen. One or two of these 

 pearling cones are used in addition to one or two sets of hullers. 

 The product taken off by the pearling cone is generally known as 

 " pearling-cone meal" and may be sold as such, although some 

 mills make a practice of mixing this product either with their bran 

 or polish, as demand or price may dictate. 



Brush. — During the milling in the hullers and pearling cone the 

 rice becomes very warm, and, hence, before further treatment it 

 is run to large cooling bins where it is allowed to remain for several 

 hours. A further reason for collecting the grain in bins at this 

 point lies in the fact that a uniform flow of rice to the brush is 

 necessary for good milling, and the brush handles rice much more 

 rapidly than the hullers or pearling cone. It is therefore necessary 

 to store the rice from the hullers and pearling cone until such an 

 amount has been partly milled that a uniform feed for the brush 

 machine is assured before it is started. From these bins the rice, 

 which is now practically white in color, but is more or less rough 

 and unsightly in appearance, is conveyed to the brush to remove 

 more of the inner bran coat and to give the rice a smoother finish. 



The brush consists of a vertical cylindrical frame covered with a 

 thick padding of soft leather strips. This frame revolves at a high 

 rate of speed within a cylinder of wire screen. The rice enters at 

 the top of the brush and is rubbed smooth by friction with the brush 

 and screen while passing to the bottom of the machine. A con- 

 siderable amount of heat develops in the brush, and it is found 

 necessary to cool the brush by passing a stream of air upward through 

 it. This air current carries with it a small amount of polish which 

 is recovered in dust collectors. The material which passes through 

 the screen of the brush, mixed with the small amount of material 

 from the dust collectors, constitutes the rice polish usually found on 

 the market. The rice leaving the brush machine is suitable for 

 market, although, as a rule, it is separated into different grades by 

 a system of screens or graders, and in many cases is given a high 

 finish by the use of a small amount of glucose and talc. 



A graphic diagram of the mill process is shown in figure 1 . 



ANALYSIS OF RICE AND ITS BY-PRODUCTS. 



With a few minor variations the process just described is followed 

 in all rice mills. It results in three by-products, namely, rice hulls; 

 a rice bran, consisting of a mixture of the stone-reel, first-huller, and 

 second-huller brans; and rice polish. 



