12 



BULLETIN 330, U. S. DEPARTMENT OF AGRICULTURE. 



been observed in use in the mills of the United States. In some 

 cases a second trumble without glucose and talc feeds supplements 

 the work of the first, and it is generally conceded that the extra 

 friction gives to the rice a brighter and more desirable luster. 



Table II shows the percentage of rice-coating material used in a 

 large number of mills in Louisiana, Texas, and Arkansas. The fig- 

 ures given were calculated by ascertaining the daily output of the 

 mills and the corresponding gallons or pounds of coating materials 

 actually being applied. The considerable variation in the quantities 

 of the coating material used, as shown in the maximum and minimum 

 columns of the table, is due to the difference in the quality of the 

 various lots of rice and to the interpretation of trade demand by the 

 mill management. The averages show that the Honduras and Japan 

 types of rices receive about the same quantities of coating materials, 

 which approximate two parts of glucose and one part of talc per 

 thousand parts of rice. 



Table II. — Glucose and tale added to milled rice. 





Number 



of 

 samples. 



Glucose (per cent). 



Talc (per cent). 



Type of rice. 



Average. 



Maxi- 

 mum. 



Mini- 

 mum. 



Average. 



Maxi- 

 mum. 



Mini- 

 mum. 





29 

 8 



0.20 

 .19 



0.46 

 .26 



0.06 

 .09 



0.07 

 .09 



0.30 



.20 



0.02 





.05 







Grading machines. — From this stage to the ultimate bagging the 

 problems met with pertain to the grading of the clean rice. How- 

 ever, if the rice is damaged or very inferior because of the presence 

 of red rice, it is often bagged ungraded and sold as " line " rice. The 

 shaker frame, which was the earliest device used for grading rice, is 

 simply a framework, mechanically operated, which supports a set of 

 inclined flat metal screens. These screens are removable at will and 

 are numbered according to the sizes of the round perforations in 

 them. The unit of measure is a sixty-fourth of an inch; hence, a 

 No. 8 screen has holes eight sixty-fourths of an inch in diameter. 

 Shaker frames are still used in practically all mills, to aid in the 

 grading work. In most cases a considerable proportion of the 

 " fancy head " grade is removed on the screens before the rice goes 

 to the cockle cylinder. 



If the quality of the rice being milled is exceptionally good an 

 extra fancy head grade is made, which consists of the largest and most 

 nearly perfect grains of the lot, with only a small percentage of broken 

 particles. This commercial grade, if of the Honduras type, consists 

 of that rice which does not pass through a No. 8^ screen on the shaker 

 frame, and, if Japan, a No. 7^ screen. In passing the rice over the 



