10 BULLETIN 35, U. S. DEPARTMENT OF AGRICULTURE. 
grapes held as well in this coarse sawdust as in the fine material and 
that the large particles separated readily from the grapes and could 
be easily shaken or blown out. 
A most effective method of dislodging the sawdust is by means 
of an air blast, which frees the particles from the bunches without 
in any way injuring their appearance. When large quantities of the 
grapes are to be separated from the filler it is advisable to accom- 
plish the work by means of such a device. In the investigations of 
the Bureau of Plant Industry a tray or frame covered with wire net- 
ting of one-fourth inch mesh has been used to good advantage. The 
packages of grapes are emptied into the trays or on the frames, and 
by means of an air blast the sawdust particles are- blown through the 
wire netting, leaving the fruit free. For grapes with a tender skin 
this blast should not be too strong, 10 or 15 pounds pressure being 
ample to dislodge all the particles. The use of an air blast is not 
necessary to free the grapes from the coarser grade of sawdust, dis- 
lodgment being accomplished by merely shaking the bunches, as is 
done with the cork-packed grapes. The air blast greatly facilitates 
the work, however, and its use is suggested from that standpoint 
alone. 
The quality of the sawdust and its method of preparation are 
of prime importance. It is necessary to have the redwood abso- 
lutely pure, as the slightest mixture of other woods, such as pine, 
cedar, or spruce has been found to taint the flavor of the grapes very 
quickly. Those who are interested in the packing of California 
grapes in this way should use every precaution to obtain redwood 
sawdust of the best quality. Some of the inquiries received by the 
Bureau of Plant Industry indicate that the importance of this point 
is not always sufficiently appreciated. Plates I, II. and III show 
natural-size photographs of the different grades of ground cork and 
redwood sawdust under observation during the course of the work. 
Plate 1, figure 1, shows the size and shape of ground-cork particles 
taken from a barrel of imported Almeria grapes. The suitability 
of this material is well known and no comment is necessary here. 
Plate I, figures 2 and 3, show the nature of the cork used in the 
Bureau experiments to show the relative adaptability of cork and 
redwood sawdust as grape-packing materials. It will be noticed that 
the coarser grade shown in Plate I. figure 2, is more uniform than is 
that used by the Spanish packers. Plate 1, figure 3, shows the fine 
cork used to determine whether or not the small size of the sawdust 
particles was responsible for the better holding quality of the grapes 
in that material. Plate I, figure 4, shows a sample of ground cork 
waste offered by one of the cork-manufacturing companies during 
1912. The shreddy nature of this material makes it unsuitable for a 
