June 15,1925 Environment and Chemical Composition of Grape Juices 1171 
vigor and general condition of the 
vines in that year, with a total rainfall 
of 35.57 inches, compared favorably 
with that of 1919, with a total rainfall 
of 58.25 inches, as well as with that 
of other years of more nearly normal 
precipitation, the variations in rainfall 
can not have played a determining 
role in chemically modifying the crop. 
Records of relative humidity were 
not kept at the Vineland station during 
the work. Detailed records are kept 
at Atlantic City and Philadelphia. 
Examination of these records indicates 
that the departures from normal 
humidity year after year are so in¬ 
considerable as to make this factor of 
no significance, and the location of 
Vineland makes it very probable 
that the same conditions prevail there. 
The Vineland temperature records 
show very slight departures from the 
50-year mean, which is no doubt due 
to nearness to the seacoast. These de¬ 
partures are too small to be signifi¬ 
cant when considered alone. 
The climatic factor which stands out 
as varying most widely from year to 
year is the amount of sunlight received 
by the plants during the growing 
period. Location subjects the Vine- 
land territory to occasional periods of 
overcast, cloudy weather at any time 
during the growing season and to fre¬ 
quent showers and fog in the late 
summer. The number of clear days 
in the period March 1-September 30, 
inclusive, varied as follows: 1919, 134; 
1920, 110; 1921, 119; 1922, 114; 1923, 
120. As pointed out in the discussion 
of climatic conditions, the number of 
clear days alone does not give an accu¬ 
rate idea as to the seasonal sunshine 
received, as partly cloudy days also 
contribute some sunshine. The num¬ 
ber of days reported as partlv cloudy 
are: 1919, 42; 1920, 70; 1921, 54; 1922, 
50; 1923, 60. In the system of re¬ 
cording used by the Weather Bureau 
branch stations, days having four- 
tenths to seven-tenths of the hours of 
possible sunshine prevented by clouds 
are classed as partly cloudy. It has 
been assumed that in the aggregate the 
partly cloudy days furnish 50 per cent 
of the possible sunshine. It is probable 
that this approximates the actual facts 
as closely as is possible in the absence 
of an accurate detailed record. 12 The 
taking of 50 per cent as an average very 
probably somewhat underestimates the 
actual amount of sunshine received, 
but does not affect the results for pur¬ 
poses of comparison. Proceeding upon 
this assumption and adding to the clear 
days for each year one-half the number 
of partly cloudy days, we have for 1919, 
155 days; for 1920, 145 days; for 1921, 
146 days; for 1922, 139 days; and for 
1923, 150 days. These figures present 
as close an approximation to the 
amount of sunlight in each of the years 
as can be arrived at from the data in 
hand. Ranked in the order of amount 
of sunlight, 1919 stands first, 1923 
second, 1920 third, and 1922 fourth. 
1921 must be separately considered, 
since the young shoots of most varie¬ 
ties were killed by frost, which retarded 
development for two or three weeks and 
reduced the size of the crop in that year. 
Consequently the amount of sunlight 
received during the season can not be 
used as a basis for comparing the crop 
with those of other years, as an un¬ 
known portion of the time, varying 
with variety, was required for recovery 
from the injury and the crop produced 
was subnormal in amount. 
As has been pointed out in the dis¬ 
cussion of the analytical data, 1923 
had a slightly larger number of vari¬ 
eties attaining maximum sugar con¬ 
tent than 1919, although 1919 had five 
days more sunlight in the period chosen 
for comparison. It was stated in the 
discussion of climatic conditions for 
1923 that the year was one of late 
ripening, the harvest period extending 
through October 11, the fruit of the 
majority of the varieties remaining on 
the vines a week to 10 days longer 
than usual. As the period September 
20 to October 11, inclusive, was one of 
high temperature and uninterrupted 
sunshine, conditions for photosyn¬ 
thetic activity were optimum, and the 
crop stored considerable sugar after 
the close of September. It is probable 
that by reason of this fact that this 
crop received fully as much sunlight as 
did that of 1919. The two years are 
characterized by the large number of 
varieties having high sugar, 1919 hav¬ 
ing 15 with maximum and 12 with 
next - to - maximum quantities, while 
1923 had 18 with maximum and 17 
with next-to-maximum contents. That 
years of high sunshine are also years 
of generally low acidity is also clear, 
1919 having the maximum in 20 
varieties and next-to-maximum in 9. 
Astringency determinations were made 
only for the years 1921-1923, inclusive, 
12 It is probable that there is considerable variation in the use of the term “partly cloudy” by different 
observers. For example, the record for March, 1921, at Atlantic City, states that the 8th, 12th, 21st, 22d 
and 27th had 92, 97, 89, 91, and 98 per cent of possible sunshine, yet it classes them as partly cloudy, while 
March 14, 1923, is classed as clear, although it is recorded as having 69 per cent of possible sunshine. July 
9, 1923, is recorded as partly cloudy, yet as having 100 per cent possible sunshine. (Monthly Meteoro¬ 
logical Summary, Atlantic City, N. J., Form 1030, for dates given.) 
