1138 
Journal of Agricultural Research 
Vol. XXX, No. 12 
THE METHODS EMPLOYED 
Collection and Preparation of 
Samples 
In any work of this character the 
value of the results hinges wholly upon 
the securing of samples for analysis 
which are truly representative of the 
crop as a whole. The method of col¬ 
lecting samples here employed was 
purposely chosen to eliminate the 
errors inherent in the selection of 
small samples of fruit which have been 
pointed out by Denny ( 19 ) and by 
Haynes and Judd ( 28 ) and was made 
easier by the fact that considerable 
quantities of the juice of each variety, 
were desired for other experimental 
purposes. In the case of the varieties 
of which there were only 10 vines, the 
entire crop of the 10 vines was harvest¬ 
ed, thus making a sample of 30 to 75 
pounds. In the case of those varieties 
of which there were 72 or 144 vines 
each, the entire crop could not be used, 
and the owners usually picked the 
fruit of a given variety for sale about 
6 to 10 days before it was judged to 
be fully ripe. Consequently the entire 
planting of a variety was examined 
and a number of vines standing con¬ 
secutively in the row and including 
equal numbers of vines trained by each 
of the methods of pruning employed 
and ranging from 15 to 40 in number 
were reserved for use in this work and 
the picking was postponed until the 
crop was fully ripe. The block of 
vines so chosen was thus as truly 
representative of the whole planting 
of the variety, in appearance and con¬ 
dition of vines and size of crop, as it 
could be made, and the entire crop 
from the block was harvested together, 
the pickers being instructed to leave 
no fruit on the vines. The samples so 
obtained ranged from 50 to 300 pounds 
in weight, usually averaging about 150 
pounds. It is believed that these 
samples were as free from the effects 
of conscious or unconscious selection 
and as truly representative of the 
whole product of the vines as could be. 
As rapidly as picked, the fruit was 
conveyed to a building near the vine¬ 
yard and pressed. Unless otherwise 
noted, all samples were cold pressed, 
i. e., pressed without previous heating. 
A large-size hand cider press was used, 
the grater being adjusted so as to 
burst the individual grapes without 
crushing the seeds. Racks and cloths 
were substituted for the slatted device 
usually supplied with such presses. 
A sufficient number of cloths were pro¬ 
vided to permit the washing of each 
cloth after it was once used and drying 
it before it was used again, and the 
press and racks were thoroughly 
cleaned and washed after the pressing 
of each variety was completed. About 
50 to 65 pounds of fruit could be han¬ 
dled at one pressing. In order to 
accomplish an extraction of juice com¬ 
parable with that obtained by the 
smaller hydraulic presses, a 6-foot 
lever was used and the screw was 
forced down as far as two strong men 
could turn it. After draining had 
stopped, the press was opened, the 
cakes were broken up and returned to 
the cloths and the pressing repeated. 
That the extraction of juice was com¬ 
parable to that obtained in ordinary 
commercial practice by the use of a 
hydraulic press is evidenced by the 
yields of juice obtained, which ranged 
from 6.9 to 8 gallons per 100 pounds of 
fruit. 
Juices expressed in this manner will 
differ appreciably in composition from 
those obtained by pressing small 
samples of fruit through muslin by 
hand, though some workers have as¬ 
sumed that such hand-pressed samples 
accurately represent the composition 
of the crop. The writer has repeatedly 
made analyses of samples made from 
the same lot of grapes, by pressing in 
the press here used, and by crushing 
the fruit, placing it in a strong cloth, 
and squeezing with the hands until no 
more juice could be expressed. In 
every case a less complete extraction 
of juice was obtained by hand pressing, 
as shown by the weight of the residues. 
Hand-pressed samples show consider¬ 
ably lower acid, higher sugar, and 
higher total solids than do those made 
with a press, and these differences, 
superposed upon the error which 
usually occurs in taking small samples, 
give analytical results materially higher 
for sugar and solids than the true ones. 
The juice was received as it drained 
from the press into enamel-lined pails 
of a size sufficient to contain the juice 
from one pressing. As soon as the 
pressing of a variety was complete the 
juice was carried into the workroom 
and sampled. If the juice from a 
variety occupied only one container, it 
was thoroughly stirred while portions 
for the various determinations were 
pipetted into beakers. If the lot of 
fruit was of such size that the juice 
filled two or more containers, an equal 
amount was measured from each, after 
thorough stirring, into another vessel, 
and the samples for analysis were taken 
from this vessel. Thorough agitation 
during the taking of samples is by no 
means superfluous, as many juices 
throw down an abundant flocculent 
precipitate immediately after pressing. 
