CHEMICAL COMPOSITION OF AMERICAN GRAPES. 9 



The two elements of prime importance in the grapes used for the 

 manufacture of unfermented grape juice, for wine making, or for 

 other by-products, are the amount of sugar and the amount of acid 

 present in the fruit; hence the work undertaken in 1908, the first 

 season at Sandusky, was confined almost wholly to sampling and 

 examining crops of grapes found at the various wineries and juice 

 factories, and to observations of the methods of vinification employed. 

 A small amount of wine was made for technical study. It was un- 

 fortunate that the investigations could not have been begun at the 

 opening of the vintage season in 1908, because the crop was especially 

 good that year for making high-class products, but it was impossible 

 to make preparations for more extensive operations than those 

 indicated. 



PEEPAEATION OF THE SAMPLE FOE ANALYSIS. 



The samples of fruit secured for 1908 were taken at the various 

 wine cellars directly from the packages as they arrived at the cellars, 

 and the name and address of the grower was invariably entered on 

 the records with each sample. About 4 pounds of fruit were taken 

 for a sample, and care was taken to secure an average of the crop. 

 These samples were crushed and pressed by hand in the laboratory 

 of the Duroy & Haines Co., who kindly furnished facilities for this 

 work. 



The preparation of the samples is a matter of considerable impor- 

 tance. Experiments on crushing in a mortar by using a pestle, on 

 crushing by hand in porcelain vessels, and also with small hand 

 grinders were made. After careful tests by these methods it was 

 found that crushing by hand is the best method of procuring a sample. 

 In this way each grape is crushed practically to the same extent, and 

 the whole mass is reduced to a pulp so much more homogeneous 

 than by any other method tried, that this one was adopted for all 

 work during the years 1909 and 1910. The stems were in every case 

 left in the pulp. 



When crushed to a pulp the sample was transferred to a piece of 

 cheesecloth folded double, spread over a porcelain dish, and the pulp 

 was pressed by gathering the edges of the cloth firmly in one hand 

 and gently squeezing the mass until the juice was extracted. The 

 pulp is in this manner reduced to a ball in the cloth, and by gripping 

 this firmly with the free hand and applying pressure properly a care- 

 ful operator can reduce the pulp to about the condition of dryness 

 arrived at by applying 1,500 pounds direct pressure in a hydraulic 

 press. The amount of pressure used will affect considerably the acid 

 present in the expressed juice; hence care is required in this manipu- 

 lation to secure comparable results. 

 5874 Bull. 14511 2 



