8 BULLETIN 330, U. 3. DEPARTMENT OP AGRICULTURE. 



capacity of 600 barrels of 162 pounds each, two sets of stones are 

 generally employed. Since the revolving motion of the stones tends 

 to keep the grains on end and all the grains in a lot of rice are not 

 uniform in length, it is found most economical to adjust the stones at 

 a. sufficient distance apart so that the best and longest grains are not 

 broken and at the same time a maximum percentage of rough rice is 

 hulled. If the stones are set too close together, it is also found that 

 the germs are removed from some of the grains instead of remaining 

 to be scoured off with the bran. The average results of the mechan- 

 ical analyses of several samples of rice of the Honduras type col- 

 lected directly from the stones are as follows : Hulled rice, 65.5 per 

 cent ; rough rice, 15.3 per cent ; and hulls, 19.2 per cent. 



Fans. — From the stones the mixture of hulled rice, rough rice, and 

 hulls is elevated to the upper mill floor to be fanned. The fanning 

 device is very similar in this case to the one used in removing the 

 dust and weed seeds from the original rough rice. The same forced 

 air that separates the hulls from the rice usually takes them to the 

 fuel house near, the boiler room, where they are eventually used as 



Fig. 4. — Typical paddy machines used in modern rice mills to separate the unhulled rice 

 (paddy grains) from the hulled rice in the process of milling. 



fuel for the mill, or, if they are not to be burned, to a grinding ma- 

 chine, where they are prepared for the market. Practically all rice 

 mills make use of the hulls as a source of power for heating the 

 boilers. Analyses of many samples of the Honduras type of rice 

 taken from the fans show how efficiently the loose hulls are removed 

 in this machine. The average results are as follows: Hulled rice, 

 81.9 per cent; rough rice, 17.2 per cent; and hulls, 0.9 per cent. 



Paddy machine. — The paddy machine is a device designed to sepa- 

 rate the rough from the clean rice in the mixture, which has been 

 fanned practically free from hulls. Essentially it consists of a large 

 inclined mechanically operated shaker, the surface of which is inter- 

 rupted at regular intervals with small vertical metallic plates which 

 divide the rice and aid gravity in making the separation. As the 

 shaking proceeds the rough rice grains, being lighter, gradually move 

 upward from the center feed and pass over the high side of the 

 machine into a trough, while the heavier, hulled grains are collected 

 under the lower side. The separation may be varied by changing 

 the speed of shaking, the angle of incline of the platform, or the 



