50 COMPOSITION OF AMERICAN WINES. 



In case the wine is shown to have received an addition of alcohol, 

 and a figure greater than 12. 5 is obtained by adding together the vol- 

 ume per cent of alcohol and the total acidity expressed as grams of 

 sulphuric acid per liter, the volume per cent corresponding to the per 

 cent by weight of "natural" alcohol is added to the total acidity 

 expressed as grams of sulphuric acid per liter (6. 53 X grams tartaric 

 per 100 cc). If the sum thus obtained is less than 12.5 the wine is 

 considered by the municipal laboratory to have received additions of 

 both water and alcohol. 



TOTAL ACIDS. 



European wines rarely contain less than 0.40 gram or more than 

 1.5 grams of total acids, calculated as tartaric, per 100 cc. The acid 

 content is often diminished by aging, by the separation of cream of 

 tartar, and by the action of certain micro-organisms. On- the other 

 hand, it may be increased by concentration and by the formation of 

 succinic and lactic acids. 



Mr. Curtis found the average total acid content in California wines 

 six months old to be 0.525 per cent for red wines and 0.570 per cent 

 for white wines. He regards as suspicious a wine which contains 

 less than 0.450 per cent. 



VOLATILE ACIDS. 



Marked variations have been noticed in the volatile-acid content of 

 wines made in dissimilar climates. This is probably largely due to 

 the differences in the temperature of fermentation. According to the 

 Freie Vereinigung bayerischer Vertreter der angewandten Chemie 

 a white wine containing more than 0.09 gram of volatile acids per 

 100 cc or a red wine containing more than 0.12 gram is to be regarded 

 as abnormal, and a white wine containing more than 0.12 or a red 

 wine containing more than 0.16 gram is to be condemned. 



It seems probable that wider limits are necessary for the American 

 wines. While it is true that excessive acidity is objectionable, and 

 that as the methods of fermentation are more nearly perfected the 

 volatile-acid content is reduced, yet it is possible that with like meth- 

 ods of fermentation the American wines will give a somewhat higher 

 volatile-acid figure than many of the European wines. In this respect 

 the American wines have improved very much in the last few years. 

 It is believed that if the products of the wineries whose samples are 

 described in this bulletin could now be examined the volatile-acid 

 content would be very much lower. A marked improvement has been 

 made in this respect in California wines in the past few years, as 



