4 BULLETIN 330, U. S. DEPARTMENT OF AGRICULTURE. 
cellulose structure of epicarp and perisperm and a 30 per cent de- 
crease in the quantity of pentosans. 
MILLING METHODS. 
EVOLUTION OF RICE MILLING. 
The rice hull is so stiff and hard as to be quite inedible, and its 
removal from the grain is in reality the fundamental process of rice 
milling. To accomplish this, various devices have been used in the 
United States. The pounding of the grain in a wooden mortar with 
a pestle by hand was succeeded by the employment of mechanical 
devices for raising the pestle and by the use of larger mortars and 
pestles covered with metal on their wearing surfaces. In some local- 
ities a further refinement of the process consisted in substituting 
revolving stones as a hulling agent before the rice was pounded. 
In Louisiana the same object was later accomplished by a machine 
called the " plantation huller," in which the rough rice was hulled 
and scoured by friction between corrugated iron surfaces. Modern 
mills employ large revolving stones for removing the hulls and a 
series of scouring machines for polishing the grain. 
PRIMITIVE METHODS. 
FARM MORTAR-AND-PESTLE MILLING. 
In early times, when the production was small and consumption 
was confined largely to the producing area, simple and cheap methods 
of milling were adequate. The farm mortar was made by burning 
or scraping a conical cavity in a block of hard wood, and the pestle 
was prepared from a cylindrical stick of similar wood by shaping and 
pointing each end and cutting down the center to a size suitable for 
a handle. Such a pestle was about 3 feet long and weighed from 
10 to 15 pounds. Figure 3 shows the type of wooden mortar and 
pestle formerly used in milling rice for home consumption. The 
rough rice was pounded until practically all the grains had been 
hulled and the broken hulls, acting" as an abrasive, had scoured off 
a considerable portion of the bran coat. The loose hulls and bran 
were blown away by the wind when the pounded mass was poured 
from an elevated pan to a receiver below. Before cooking such rice 
it was necessary to remove by hand picking the remaining paddy 
or unhulled grains, which were always present. Since the capacity 
of a mortar was generally less than a bushel and the operations were 
all done by hand, this method was inadequate for the milling of rice 
except on a small scale. 
MORTAR-AND-PESTLE MILLS. 
As the demand for rice increased, it was found economical to em- 
ploy larger mortars and mechanical means for pounding and winnow- 
