131 
Kaperiment 1V.—The meat from four nuts was ground and spread in a 
layer of a depth of about 3 centimeters in shallow glass dishes. 'The 
initial temperature was 60°. 
Actual time of drying, 9 hours. 
Maximum temperature, 75° C. 
Vacuum, 660 millimeters. 
Steam pressure, 0.7 kilo per square centimeter (about 10 pounds). 
Kaperiment V.—Four coconuts were split in halves and put into the 
machine, the latter being left partly open and with no vacuum. 
Actual time of drying, 11 hours. 
Highest temperature, 86° C. 
Steam pressure, 0.7 kilo per square centimeter (about 10 pounds). 
Therefore, under the best conditions obtainable (temperature 85° and 
vacuum 635 to 660 millimeters), the minimum time required for vacuum 
drying was five and one-half hours." ; 
If we are to form our judgment from the great efficiency of the 
vacuum evaporators used for sugar solutions and for many other liquids, 
it might be supposed that this process would be equally advantageous 
for coconuts. However, the two conditions are altogether different. In 
the case of solutions we have a thin layer of liquid in direct contact with 
a heated surface, the evaporation taking place so rapidly that the space 
above the liquid is constantly saturated with moisture; the main object 
of these machines is to remove and condense the surplus water vapor as 
rapidly as possible and by so doing to allow the evaporation to proceed at 
a comparatively low temperature. The water in coconut meat, on the 
other hand, which at the most is not greater than 50 per cent of the 
total weight of material, under the best conditions, diffuses very slowly 
through the cells of the copra to the surface, the removal of moisture- 
laden air therefore becoming a matter of secondary importance. The 
principal consideration is the constant application of as much heat. to 
the entire surface of the material as the latter can endure without becom- 
ing burnt. That this condition is not fulfilled in the best manner ‘by 
a vacuum drier is chiefly due to the poor conductivity of the rarified air 
which it is necessary to heat. Although the temperature of the steam 
plates in the drying oven is from 100° to 110°, that of the partial 
vacuum immediately above and surrounding the copra, even after several 
hours, rarely rises above 75°. To this local superheating for a long 
period of time at the point of contact with the plates, probably is due the 
brown color and slightly burnt taste which vacuum-dried copra almost 
invariably possesses. 
For the sake of comparison I append the following table showing the 
"This does not include the time necessary to produce steam and to heat up the 
drier. These items must~ be considered unless the apparatus is: to run con- 
tinuously. ; Beer tat in aby 
