278 INTERNATIONAL CONGRESS OF VITICULTURE 



in most cases high for 1909. The fruit for that year was poorly ripened in 

 many instances, and the analyses were made promptly before precipitation 

 could occur. The analytical work for the years 1910 and 1911 was completed 

 promptly on the unaltered sample. 



The average sugar content of the several varieties given in the table 

 are remarkably constant for each kind barring samples from Northern Ohio 

 for 1909, but the acid content is not so stable as the sugar content. It is 

 quite probable that the acid is much more readily affected by climatic condi- 

 tions, vigor of plants, healthfulness of foliage, etc., than the sugar content. 

 These comparisons should not be made between the different districts but 

 on samples from the same district. Note this point as to samples of Norton 

 from Northern Ohio and Virginia. The acid-sugar ratio illustrates sharply 

 the variation in the relation of these most important constituents. 



While I am not prepared to propose at this time any final conclusion 

 as to the limits within which the acid-sugar ratio may vary and yet produce 

 a potable wine or unfermented grape juice for beverage purposes, I am quite 

 certain that this cannot be arbitrarily fixed for the several varieties given 

 in the table. Surely when we have sufficient data it will be comparatively 

 simple to fix the ratio within reasonable limits for any particular variety. 

 But because of the fact that the acid properties of the grape juice will vary 

 much in constitution, the resultant by-products will vary likewise in the 

 diminution of acid strength which will result from proper handling of the 

 product. That is, the reduction of acid by precipitation of tartar and the 

 breaking up of malic acid, must necessarily depend upon the percentage of 

 these substances in the total acid properties of the fruit must. 



The bearing on this point on the wine produced is brought out in the 

 subsequent discussion under "Composition of Pure Wines from American 

 Native Grapes." 



Table I which follows presents the average composition, as to the more 

 important organic elements, of eight of our native grapes. 



