4 ENOL.OGICAL STUDIES. 



of the greatest importance. As is well known, the predominant acid 

 in ripe grapes is tartaric. The presence of this acid, either in a free 

 state or in combination with lime or potash, is necessary to give to 

 the grapes the peculiar flavor for which they are noted. In other 

 words, the acid content of the grape is one of the ingredients of chief 

 importance from an organoleptic point of view. A grape which is 

 without acid would be totally insipid, and would yield a juice not 

 much better than sweetened water. On the other hand, a grape juice 

 in which the acid is excessive is unpalatable, at least to most persons. 

 Hence the production of a grape with the proper degree of acidity to 

 give character and not enough to impair taste is of great importance. 



The studies which have been made and which are detailed in the 

 following pages throw much light on this important problem, even 

 though they are far from complete, indicating what varieties of 

 grapes and what conditions of environment give the best results. 



Equally important from the point of view of vinification is the 

 sugar content of the grape. The only source of natural alcohol in 

 wine is fermentation of the sugars which exist in the original grape. 

 These sugars exist in combination with other bodies, many of which 

 enter into the finished product and serve to give it character and 

 quality. In fact, the smaller the quantity of alcohol which can be 

 secured in the finished wine, and at the same time permit of its 

 manufacture and keeping, the better. Other things being equal, the 

 wine which has the smallest percentage of alcohol is to be preferred. 

 The data which have been secured indicate the varieties of grapes 

 which give the best percentage of sugar for proper fermentative 

 purposes. 



These studies will lay broad and deep the foundation for the prac- 

 tical working out of the problem of the utilization of grapes for the 

 various purposes for which grape products are employed. While the 

 work has been carried on under the general direction and supervision 

 of the Chief of the Bureau of Chemistry, the details of it and the 

 technique of the processes have been in the hands of Mr. William B. 

 Alwood, who has given to the work his undivided attention and has 

 with enthusiasm and success attacked the many problems which 

 have been presented. 



H. W. WILEY, 



Chief of Bureau. 



WASHINGTON, D. C., March 10, 1911. 



