WINES. 



341 



The Bavarian Chemists' Union depart from this method by drying 

 the residue to a constant weight. 



It is of great importance that chemists should adopt a uniform method 

 of analysis, as results differ considerably by different methods. This is 

 shown by the following results obtained from the samples analyzed by 

 me, most of which were subjected to analysis by both methods, that is, 

 drying to a constant weight and drying a certain length of time. In 

 the very sweet wines, of course, such as the Angelica, Muscat, &c., con- 

 taining so large a percentage of sugar, it can only be satisfactorily de- 

 termined by using a small quantity, allowing it to flow well over the 

 bottom of the dish, and drying to a constant weight as nearly as pos- 

 sible. 



Comparison of methods for the estimation of extract in wine. 



I have adopted the results obtained from the estimation by drying to 

 a constant weight, and would recommend the following procedure for 

 the determination of extract in wine. Weigh out 10 to 50 grams of the 

 wine (according to its content of sugar) into a flat-bottomed platinum 

 dish, evaporate on the water bath and dry the residue at 100 C. in an air 

 bath, until a constant weight is obtained. This may be known to be 

 the case when by weighing the dish and contents at frequent intervals 

 (15 minutes) the losses in weight are found to be slight and equal for 

 the same length of time of drying. 



ACIDITY. 



The total acidity of wines may be determined by titration with 

 ~ or TTI alkali. The end reaction may be observed by means of a drop 



O -Lvf 



brought into contact with delicate litmus paper, which, while not en- 

 tirely satisfactory, still is probably the best method we have at hand, 

 any means for decolorizing the wine so as to admit of the use of other 

 indicators being likely to change the content of acid. I have found 

 that by the use of turmeric paper in connection with the litmus, the 

 establishment of the point of neutralization is greatly facilitated. 

 4450 No. 13, pt. 3 6 



