Vol.35, 1916] AGRICULTURAL OHEMISTEY — AGROTECHNT. 109 



and more extended examination, during 1911 and 1912, of the changes in the 

 sugar and acid content of several varieties of grapes. The examinations were 

 made at Sandusky, Ohio, and Charlottesville, Va. 



Analytical results obtained from the juice samples submitted indicate that 

 " the total acid percentage is practically the same in the green fruit of Con- 

 cord in both juice and whole-fruit samples, and this relation continues so 

 nearly throughout the entire period that either result may be taken as fairly 

 expressing the content. The total acid is decidedly higher in the juice sample 

 of green Catawba than in the whole fruit for the first three samples taken; 

 then the acid content of both samples becomes about what may be expected of 

 check samples. 



" The results for total tartaric acid in the juice and whole fruit are not 

 so uniform as for total acid. Yet for the Concord samples . . . there is a 

 degree of uniformity which is striking, considering the difficulty of sam- 

 pling. . . . The Catawba samples show much difference in the green fruit, but 

 the later samples approach uniformity. 



" There is a striking dissimilarity in the percentage of tartaric acid for the 

 Concord samples at Sandusky and Charlottesville throughout the period of 

 investigation. Those taken at Sandusky show much less variation than the 

 Charlottesville samples and the former show approximately the same amount 

 at the close of the season as for the partly colored samples first taken, while 

 the Charlottesville samples show a very marked decline in tartaric acid for 

 both the juice and fruit samples. . . . 



" It would appear that the crushed fruit invariably yields decidedly the 

 greater part of the free tartaric acid content when pressed. . . . These results 

 support 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 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 tataric acid." 



The composition of the whole fruit was also studied. " The volume and 

 weight of the Concord berries did not show marked changes in size of the fruit 

 throughout the period of the examinations of the samples, but for Catawba 

 there was a decided increase of about 39 per cent in volume and about 44 per 

 cent in weight. It appears that this late-maturing variety for that season 

 shows considerable change in size and weight of berries during the period from 

 coloring to maturity. 



" On calculating the actual weight of acid in grams present for each sample 

 of 100 berries examined there is shown in a positive manner ... a fairly 

 constant diminution in total weight of this ingredient. . . . There are some 

 apparently abnormal results ; that is, during some periods the actual weight of 

 acid increased slightly, yet this is invariably reversed for the subsequent 

 analysis and the comparison of the first samples and the last taken show a posi- 

 tive loss in total weight of acid present in 100 berries for all the crops analyzed. 

 The data appear to establish the fact that there is a very decided loss in total 

 weight of acid as the fruit ripens." 



The analytical data are presented in detail in tabular form. 



The urease of soy beans, W. C. de Gbaatf and J. E. van dee Zande (CJiem. 

 Weekbl., 13 {1916), No. 10, pp. 258-264) .—From the results of their investiga- 



