336 PLANTS USED BY INDIANS OF MENDOCINO COUNTY, CAL. 
and it fits so closely and is held so firmly to the stone that no meal is 
lost. This process requires a very considerable amount of time, and 
consequently the everlasting thump, thump, thump, of the pestle is a 
characteristic sound heard at many of the Indian settlements about 
midday. 
Although the meal thus produced is quite fine, it is mixed to a 
greater or less extent with coarser "partic ‘les, which are most carefully 
removed in the following manner: The meal is spread out evenly on 
the separator, a circular piece of hasket-work shown in fig. 72, and then 
the separator being held inclined toward the body, the meal is, by 
vigorous shaking, thrown up and down upon it until all of the coarser 
particles have rolled off into the basket which has been placed to receive 
them. This product, however, is not considered fine enough. The 
meal is easily loosened up by tapping the plaque gently. The shaking 
operation is then repeated again and again until at about the seventh 
time it adheres so firmly that it has to be beaten off by sharp blows 
with a long bone which is kept at hand for the purpose. Any stray 
bits of meal that have dropped around the baskets are carefully scraped 
up from the ground by means of a brush made of the outer fibers of 
soap root (CAlorogalum pomeridianum) and carefully added to that 
which has to be reground. Very little dirt gets into the meal in this 
way, for the ground is either so selected as to have a hard, damp, and 
even surface which can be kept free from supertluous dirt by sweep- 
ing, or, which is more generally the case, it is already hard and greasy 
from long-continued use. 
The meal thus carefully ground is still astringent and bitter on 
account of the tannin and the bitter principle which the acorns contain 
in quantities varying with the different species. Both of these sub- 
stances are deleterious to health and interfere with digestion, and 
hence it has been found necessary to remove them as completely as 
possible before the meal can be used for food. Water will remove 
both. It would, however, be practically impossible to dissolve them 
out from such an oily ms terial if the meal were not first ground to an 
impalpable powder. The reason for taking so much pains in that pro- 
cess Is therefore quite evident; a very great additional advantage lies in 
the fact that the finer the meal the more easily and fully it is digested, 
The process of removing the bitter substance and the tannin. is 
essentially the same with all the tribes, and consists in mixing the 
meal with water ina shallow depression which is made in sand or some 
porous material and allowing the water to percolate through the mass 
until the bitter taste has disappeared. A couple of hours are usually 
required for the operation. As originally carried out this filtration 
was done in sandy soil, and that is the kind of place still preferred; 
but since the Indians have been located on farms of their own, several 
have erected special sand filters and a few of them have substituted 
