CHEMICAL COMPOSITION OF AMERICAN GRAPES. 13 



INVESTIGATION OF 1909. 



During the season of 1909 preparation was made to extend the 

 work by equipping a laboratory at Sandusky, Ohio. Accommodation 

 was thus provided for handling a large number of samples and for 

 making fermentation experiments on the different varieties of wine 

 grapes. The report on the fermentation experiments is not, how- 

 ever, included in this report, which deals only with the composition 

 of the fruit samples. A canvass of the Lake Erie district and as 

 far east as the central New York grape district was made during 

 August and September, 1909, and correspondents were selected at 

 several points of importance who were relied upon for samples of the 

 crop for the laboratory work, and a number of whom rendered 

 valuable assistance. The samples were sent by express or boat, 

 usually in small baskets, to the Sandusky laboratory, where the 

 notes on quality and the chemical examinations were made. 



This arrangement furnished a large number of samples direct from 

 the growers, but others were also secured from the wine cellars in 

 Sandusky at such periods as seemed most likely to furnish data on 

 the full range of the fruit crushed for wine. However, samples from 

 the wine cellars were not usually considered as representing indi- 

 vidual crops during 1909, but were regarded as a composite of the 

 stock on hand at the time the sample was taken. From the American 

 Wine Company composite samples were taken of the expressed juice 

 as it was collected in the settling tank. Such samples are reported 

 under the names of the several cellars. 



The data determined at the time of sampling during 1909 comprise 

 a Brix reading on the fresh must, and titration for total acid as soon 

 as the sample was crushed and pressed; in most cases the sample 

 was further analyzed by determining the specific gravity by pyk- 

 nometer, the total solids, sugar-free solids, and total sugar. Inver- 

 sion was only resorted to when the results showed excessive sugar- 

 free solids by direct determination. Volatile acid was not deter- 

 mined on the fresh fruit during 1909, as the data for the previous 

 year showed this to be unimportant. Samples which were not 

 analyzed as fresh fruit were treated with pure mercuric chlorid and 

 stored for analysis later, 0.2 gram being used for 400 cc of juice. A 

 correction for the use of mercuric chlorid was found to be unneces- 

 sary when the pure crystallized salt is used. The results on acid in a 

 juice are usually lower if the sample has stood in a bottle for some 

 tune, owing to the precipitation of crude " tartar." Tests on a 

 number of varieties showed this to amount approximately to 0.064 

 gram per 100 cc for white juice and 0.051 gram for red juice. The 

 results given in the table are not, however, affected by this fact, 

 because the acid was determined in the fresh juice. 



