30 BULLETIN 330, U. S. DEPARTMENT OF AGRICULTURE. 



by milling plants employing mechanical power for operating the 

 machinery. Mortars and pestles were enlarged, and screens, fans, 

 polishing brushes, and hulling stones were introduced. In Louisiana 

 small iron " plantation hullers " were used to scrape or scour off the 

 hulls and the bran coats in a single operation. 



With two or three exceptions, the 55 modern rice mills of the 

 United States in operation in 1914 were located in Louisiana, Texas, 

 and Arkansas. Various complex machines clean and scour the rice 

 and prepare it for the market. Screens and fans remove the foreign 

 material from the rough rice, which is then hulled between large re- 

 volving stones. Fans blow out the loose hulls and paddy machines 

 separate the grain not hulled by the first treatment with the stones. 

 Hullers, pearling cones, and brushes scour from the hulled grain the 

 light-brown bran coat, which is separated in a powdery form through 

 fine wire screens. In the trumbles the rice often receives a coating 

 of glucose and talc approximating two-tenths of 1 per cent of the 

 former and one-tenth of 1 per cent of the latter. The coating mate- 

 rials and the friction in the trumbles produces a bright luster. Grad- 

 ing the milled rice according to the size of particles is effected by 

 shaker frames fitted with screens having perforations of various 

 sizes ; by reels, the sections of which are covered with wire of differ- 

 ent sizes; and by cockle cylinders, which in revolving pick up the 

 broken pieces in depressions in their inner surfaces and deposit them 

 upon an inclosed apron suspended from the stationary axle. The 

 various grades are bagged separately in pockets of 100 pounds each. 



Excessive breakage occurs when rice of the Honduras type is milled 

 in a " plantation huller," and the finished product may have less than 

 10 per cent of whole grains. The Honduras type of rice milled in 

 a modern plant is broken to a considerable extent during the scouring 

 process, which reduces its whole-grain content from 75 per cent as it 

 leaves the paddy machine to 50 per cent as it leaves the brush. The 

 Japan type of rice, on account of its shape, is broken to a less extent, 

 and under similar conditions averages 92 per cent and 80 per cent, 

 respectively, of whole grains. 



Approximately 10 per cent of the weight of the rice kernels of both 

 Honduras and Japan types is removed by the scouring off of bran 

 coat and germ. In other words, the average weight per thousand 

 kernels of rice of the Honduras type is reduced from 24.1 to 22.8 

 grams by the action of the hullers and pearling cone, and then to 22.1 

 grams by the brush. The hullers and pearling cone reduce the weight 

 of the grain of Japan rice from 22.4 to 21.5, and the brush further re- 

 duces the weight to 20.2 grams. 



Chemical analyses show that the old mortar-and-pestle mills re- 

 moved a somewhat smaller proportion of ash, ether extract, and crude 



