1G 



BULLETIN 656, U. S. DEPARTMENT OP AGRICULTURE. 



change from the supersaturated to the saturated condition is very 

 gradual, so that the time allowed for the precipitation has a decided 

 effect upon the amount of cream of tartar retained in solution. 

 This is shown in Table 9, wherein it will be noticed that the cream of 

 tartar content has diminished during the additional one year of 

 storage. Shaking a grape juice hastens the precipitation of cream 

 of tartar, and brings about an equilibrium much more rapidly than 

 simply allowing the juice to stand undisturbed. It seems therefore 

 that the process of manufacture could be shortened, if after a few 

 days' storing the juice were given a thorough shaking, and then 

 allowed to stand for the rest of the storage period. It also seems 

 reasonable to believe that this extra manipulation would give a 

 much brighter finished product. 



Table 9. — Chemical composition of Concord grape juice after 4 months' storage and after 



16 months' storage. 



Storage period. 



Months. 

 4 



Gms. 

 17.43 



16 



17.48 



4 



16.47 



16 



16.47 



4 



17.85 



16 



17.80 



4 



19.00 



16 



19.10 



4 



18.53 



16 



18.48 



4 



18.79 



16 



18.80 



4 



17.85 



16 



17.80 



16 



18.87 



Maximum: 

 4 



19.00 



16 



19.10 



Minimum: 

 4 



16.47 



16 



16.47 



Average: 

 4 



18.11 



16 



Average loss 



18.10 

 .01 



Peret 



0.07 



.07 



.13 

 .14 



.05 

 .07 



.07 

 .07 



.06 

 .07 



.13 

 .07 



.07 

 .07 



.20 

 .13 



c2rH 



Gms. 

 14.45 

 14.60 



13.87 

 14.00 



14.42 

 14.54 



15.70 

 15.90 



15.06 

 15.20 



15.48 

 15.60 



14.30 

 14.55 



15.47 

 15.64 



15.70 

 15.90 



13.87 

 14.00 



14.84 

 15.00 





Gms. 

 14.40 

 14.70 



13.82 

 13.98 



14.36 

 14.64 



15.77 

 15.95 



15.06 

 15.30 



15.68 

 15.58 



14.43 

 14.49 



15.41 

 15.64 



15. 77 

 15.95 



13.82 

 13.98 



14.87 

 15.04 



Gms. 

 2.9S 

 2.88 



2.60 

 2.47 



3.43 

 3.26 



3.30 

 3.20 



3.47 

 3.28 



3.31 

 3.20 



3.55 

 3.25 



3.48 

 3.23 



3.55 

 3.28 



2.60 

 2.47 



3.27 

 3.10 



Gms. 



0.95 



.94 



.83 

 .S3 



1.10 

 1.06 



1.11 

 1.14 



1.13 



1.10 



1.13 

 1.14 



1.19 

 1.20 



1.09 

 1.10 



1.19 

 1.20 



1.07 

 1.06 



Gms. 



0.68 



.67 



.65 

 .60 



.82 

 .72 



.69 

 .65 



.83 

 .70 



.65 

 .60 



Gms. 



0.15 



.20 



.13 

 .16 



.27 

 .28 



.37 

 .41 



.22 

 .26 



.37 

 .41 



Gms. 



0.58 



.51 



.57 

 .49 



.58 

 .41 



.43 

 .35 



.54 

 .38 



.55 

 .36 



.56 

 .38 



.56 

 .41 



.58 

 .51 



.43 

 .35 



Gms. 



0.31 



.25 



.31 

 .26 



.35 

 .26 



.23 

 .22 



.22 



.31 

 .25 



.35 

 .26 



.23 

 .22 



.30 

 .24 



.06 



o"3 



a-ss 



.5 05 



fiSg 



Cc. 

 31.0 

 27.0 



30.4 

 25.8 



30.8 

 21.6 



23.0 

 18.6 



28. 8 

 20.0 



29.0 

 19.4 



30.0 

 20.0 



29.6 

 21.8 



31.0 

 27.0 



23.0 

 18.6 



29.1 

 21.8 



7.3 



Cc. 

 4.2 

 4.6 



4.4 

 3.8 



5.8 

 7.6 



4.4 

 7.0 



4.6 

 6.0 



4.4 

 6.2 



4.2 

 6.0 



6.0 

 6.0 



6.0 

 7.6 



4.2 

 3.8 



4.8 

 5.9 



9 I 

 Eh 



Gms 

 0.16 

 .14 



.13 

 .12 



.26 

 .20 



.33 

 .16 



.33 

 .16 



.22 



.17 



.26 

 .16 



Small amounts of alcohol have a decided effect on the general 

 clarification of a juice, lowering the viscosity and insuring a better 

 precipitation of cream of tartar. Table 11, group 2, shows that 



