6 BULLETIN 952, U. S. DEPARTMENT OF AGRICULTURE. 
The tannin content in the mother liquid from which the cream 
of tartar was crystallized was found to be too low to be considered 
as a commercial product. 
PREPARATION OF GRAPE POMACE FOR THE MANUFACTURE OF 
JELLY AND OIL. 
Scarcely enough pomace is produced at any one factory to pay the 
individual plant for the immediate utilization of both skins and _ 
seeds. Since, however, the pomace as it.1s produced contains about 
50 per cent of moisture, which is conducive to rapid spoilage, atten- 
tion was directed along the line of preparing this wet pomace in such 
a way as to permit it to be stored and manufactured later into the 
various products or to be shipped to some central utilization plant 
which could handle the entire output from the several grape-juice 
plants. 
A plant handling even a comparatively small tonnage of grapes 
could perhaps work up the skins into jelly at a good profit, but it 
could not profitably extract the oil from the seed, since for this 
purpose a large, comparatively expensive oil mill would be required. 
Fig. 4.—A direct-heat drier. 
To extract the jelly stock from the skins they must first be boiled 
in a small quantity of water and then pressed in hydraulic presses. 
This would necessitate either the installing of additional presses or 
the reducing of the quantity of grapes handled; in the latter case 
the output of juice would be curtailed. Experiment has proved that 
the pomace can be satisfactorily dried, the seeds and skins separated, 
and each worked up as desired. There would thus be no curtailment 
of the output of juice because of reduction in the quantity of grapes 
handled, nor would there be any added expense incurred for in- 
stalling additional presses. | 
The pomace may be dried by means of driers of. the direct-heat 
type (fig. 4) or the steam type (fig. 5). In either case the wet pomace 
should be disintegrated and conveyed into the machine in a continu- 
ous stream. Both driers rotate on a horizontal axis. The material 
enters the driers at one end in a continuous stream and passes 
out at the other end in a dry condition. The heated air current 
enters at the discharge end and leaves at the entering end, thus 
working on the counter-current principle. The two types of 
