SUGAR AND ACID IN GRAPES DURING RIPENING. 21 



Table 3. — Comparison of sugar and add elements in Cataviba fruit, 1911-12. 











Tartaric acid. 









Dates when 



Sugar. 



Total acid. 











I ixed acids 



other than 



tartaric. 



Cream of 



sampled. 



Total. 



Free. 



tartar. 



1911 



1912 



1911 



1912 



1911 



1912 



1911 19 



12 



1911 



1912 



1911 



1912 



1911 



1912 



Aug. 20 



Sept. 9 



7.22 



6.68 



3.35 



3.02 



0.98 1 



08 



0.22 



0.65 



2.75 



2.10 



0.75 



0.41 



Aug. 23 



Sept. 12 



9.46 



9.35 



2.96 



2.48 



1.01 



90 



.22 



.45 



2.35 



1.80 



.80 



.40 



Aug. 27 



Sept. 17 



11.58 



10.38 



2.21 



2.12 



.79 



90 



.15 



.47 



1.74 



1.44 



.65 



.45 



Aug. 30 



Sept. 24 



12.32 



11.33 



1.98 



1.74 



.74 



73 



.08 



.20 



1.57 



1 28 



.67 



.53 



Sept. 3 



Oct. 1 



15.24 



12.75 



1.50 



1.63 



.59 



80 



.05 



.31 



1.18 



1.07 



.53 



.54 



Sept. C 



Oct. 7 



16.08 



13.79 



1.28 



1.53 



.53 



80 



.03 



.23 



1.00 



1.02 



.48 



.61 



Sept. 10 



Oct. 16 



16.28 



15.35 



1.19 



1.34 



.57 



78 



.19 



.23 



.81 



.83 



.37 



.61 



Sept. 13 



Oct. 23 



17.28 



15.01 



1.12 



1.28 



.60 



64 



.08 



.08 



.78 



.91 



.50 



.59 



Sept. 20 



Oct. 29 



19.44 



16.49 



.99 



1.22 



.48 



75 



.00 



.23 



.73 



.73 



.53 



.57 



Sept. 27 



Nov. 4 



19.94 



16.77 



.89 



1.28 



.50 



S4 



.00 



.23 



.63 



.74 



.53 



.71 



Oct. 4 



Nov. 8 



19.45 



16.39 



.95 



1.09 



.58 



79 



.04 



.29 



.64 



.55 



.56 



.52 



The crop of 1911 was of excellent quality for wine making pur- 

 poses, while that of 1912 was distinctly poor, yet the sugar content 

 varies only about 3 grams at the final examinations given in Table 3. 

 This result agrees with our study of general crop samples in good 

 and poor crop years, as shown in Bureau of Chemistry Bulletin 145. 



The acid elements are more difficult and complex as to comparison. 

 In total acid the crop of 1911 exceeds that of 1912 for the first several 

 samples compared, but gradually declines until it falls below the 

 latter. The final difference, however, is not marked. The fact 

 that free tartaric acid in appreciable quantity continues present in 

 the 1912 crop is important from a manufacturing point of view, 

 because this acid can not be eliminated from the products except 

 by the artificial introduction of a base such as potassium or calcium. 



The fixed acids other than tartaric (malic) are interesting in that 

 for the good crop year (1911) the values obtained in the early stages 

 were much greater than in 1912, while at the end of the season the 

 two crops were about alike. The total tartaric acid of the poor 

 crop (1912) sensibly exceeded that of the 1911 crop and the free tar- 

 taric acid markedly exceeded that found in 1911 in the early samples 

 and at the time of harvesting still maintained this excess. 



The remarks on the analytical results for cream of tartar given 

 under "Crop of 1911" apply to the consideration of the results 

 obtained for the juice samples analyzed in 1912. The juice samples 

 of 1912 also show exceptions which, though not so marked, are 

 noticeable. The varieties sampled in 1912 show, with one exception, 

 an increase of cream of tartar as the fruit matured, whereas in 1911 

 the samples are not uniform in this regard. This lack of logical 

 results in regard to the content of cream of tartar, and also other 

 considerations, led us to examine whole fruit samples in 1912. The 

 fruit sample was treated in such manner that the entire content of 



