SUGAR AND ACID IN GRAPES DURING RIPENING. 9 
our previous determinations and show that the Concord juice loses 
free tartaric acid more completely than the Catawba. 
The results for cream of tartar show that in every instance save 
one the juice sample carries a smaller percentage of cream of tartar 
than the whole fruit. The one exception, No. 3588, is affected by 
an evident error and is excluded from consideration. The excess, in 
per cent, of cream of tartar in the whole fruit is sufficient to support 
a previous statement that this substance exists as crystals and that 
some of these are retained in the pulp when the fruit is pressed. 
The constant increase of cream of tartar both in the juice and fruit 
samples follows naturally from the disappearance of free tartaric 
acid. The results for 1912 are in this respect more logical than those 
for 1911. 
The data given under fixed acids other than tartaric are considered 
by the authors to be remarkably interesting. It is shown that the 
total content of tartaric acid remains nearly constant, especially 
when the whole fruit samples are compared, but these other acids, 
which we have considered as mostly malic, show such a steady aad 
sharp decline that one is forced to accept conclusions derived from 
the data given in Table 5. The reduction in the percentage of acid 
under this head reaches two-thirds to three-fourths of the entire 
amount given for the first samples taken. 
ANALYTICAL RESULTS ON THE JUICE SAMPLES. 
CROP OF 1911. 
In Table 1 the condition of the fruit on the vines at the time of 
sampling and the results of the analyses of samples both at the 
Sandusky and Charlottesville laboratories are given in detail. The 
period covered by the analyses at Sandusky was carried beyond the 
wine-ripe condition, except in the case of the Norton, which was 
destroyed by the berry moth x before it was fully ripe. This con- 
tinuation of the analyses was for the purpose of following the changes 
that occur in the fruit even to the natural destruction of the crop. 
The high temperature of the fall season at Charlottesville is not 
favorable to holding samples at that point after they are fully ripe, 
hence the data for that locality cover only the period to full maturity. 
1 Polychrosis viteana Clemens. 
12253°— Bull. 335—16 2 
