5*4 Journal of A gricultural Research voi, i, no. 6 
Table I .—-4 na lyses of Concord grapes in IQI2, giving ihe percentage by weight of acids 
and acid salts. 
Portion analyzed. 
Total acid. 
Total tar¬ 
taric acid. 
Free tar¬ 
taric acid. 
Cream of 
tartar. 
Hulls exhausted with water. 
0.429 
. 141 
1.065 
a o. 589 
•054 
• 7 2 4 
O. 08 
. OO 
. 20 
0. 56 
.07 
• 59 
Juice pressed from hulls. 
Juice pressed from pulp. 
° The results show for the samples of “hulls” a greater content of tartaric acid than the total titratable 
acid of the samples. This is always the case in grape samples where the “acids other than tartaric” fall 
below a certain proportion. 
The results show that the juice pressed from the hulls is very low in 
acid and acid salts, and that, while the organic matter remaining in the 
hulls after pressure is less than half as acid as the pulp, it is rich in tar¬ 
taric acid and cream of tartar, in these regards nearly equaling the 
percentage found in the juicy pulp. The actual weight of the pressed 
hulls was 304 grams, or one-fifth of the original sample of fruit. From 
the results given, it would appear that the hulls when pressed dry still 
retained the crystals observed with the microscope, and actual observa¬ 
tion has demonstrated this fact. The results for tartaric acid and 
cream of tartar settle the point as to the composition of these crystals. 
Analyses of like import were made at Sandusky, Ohio, of samples of 
Catawba and Concord grapes. The results show that the acid content 
of the soft layer of cells attached to the hulls is proportionally richer in 
tartaric acid and cream of tartar than the pulp. 
In 1913 the microscopic examinations were begun much earlier, and 
four varieties of grapes were included—Delaware, Concord, Niagara, 
and Norton. The presence of crystals of bitartrate of potassium could 
be observed before the berries were all colored, and the analyses of 
partly ripe fruit confirm the results of 1912. These samples were sep¬ 
arated into two portions only, the hulls and the pulp, as noted above; 
then each sample was completely exhausted of soluble organic matter 
by repeated macerations and heating in distilled water. Table II gives 
the results for one set of samples from each of two varieties. 
Table II .—Analyses of grapes in IQ13, giving percentage by weight of acids and acid 
salts 
Concord. 
Portion analyzed. 
Total acid. 
Total tar¬ 
taric acid. 
Free tar¬ 
taric acid. 
Cream of 
tartar. 
Hulls.... 
Pulp. 
95 
I- 43 
a l. II 
• 79 
0 
.04 
i- 33 
.82 
Niagara. 
Hulls.. 
0. 67 
a °. 03 
0 
I. 18 
Pulp. 
.96 
• 83 
. 18 
• 57 
* The results show for the samples of “hulls” a greater content of tartaric acid than the total titratable 
acid of the samples. This is always the case in grape samples where the “acids other than tartaric” fall 
below a certain proportion. 
There are crystals other than bitartrate present in the fruit, but this 
paper is intended only to record an observation which may have peculiar 
interest. Further details of the investigation will appear later. 
