344 FOOD AND FOOD ADULTERANTS. 



ASH. 



The ash may be estimated iu the residue from 50 to lOOcc. of the wine. 

 If 50cc. have been used for the estimation of the extract, the same sample 

 will serve conveniently for incineration. Thisoperation is best performed 

 in a muffle, and must be very carefully carried out, at as low a heat as 

 possible. If the ash does not readily burn white, it should be treated 

 with a little water to dissolve the alkali salts, the dish placed in such 

 a position as to bring the water away from the undissolved ash, the 

 water evaporated, and the incineration completed. Little difficulty is 

 generally experienced in getting- in this way a very satisfactory white 

 ash. 



GLYCERINE. 



The estimation of glycerine in wines, if it could be made with exact- 

 ness, would be a very important one, as the glycerine is produced by 

 the fermentation of the sugar, and the quantity formed is presumably 

 fairly constant for the same amount of sugar fermented. This being 

 the case, the quantity of glycerine in a wine should be a good index of 

 the quantity of sugar which had undergone fermentation, and would 

 thus show whether alcohol had been added to the wine. Unfortunately, 

 the amount of glycerine present is so small, and its exact estimation so 

 difficult on account of its volatile nature, that it is rather an unsafe re- 

 liance. The Germans attach considerable weight to the determination 

 in establishing the character of a wine, using the following method : 



One hundred cc. of wine (sweet wines excepted) are evaporated in arooniy, not too 

 shallow, porcelain dish, to about lOcc., a little sand added, and niilk of lime to a 

 strong alkaline reaction, and the whole brought nearly to dryness. The residue is 

 extracted with 50cc. of 96 per 'cent, alcohol on the water bath with continual stir- 

 ring. The solution is poured off through a filter and the residue exhausted by treat- 

 ment with small portions of alcohol. For this 50 to 150cc. are generally sutlicient, 

 so that the, entire filtrate measures 100 to SOOcc. The alcoholic solution is evaporated 

 on the water bath to a sirupy consistence. (The principal part of the alcohol may 

 be distilled off, if desired.) The residue is taken up by lOcc. of absolute alcohol, 

 mixed in a stoppered flask with 15cc. of ether and allowed to stand until clear, when 

 the clear liquid is poured off into a glass-stoppered weighing glass, filtering the last 

 portions of the solution. The solution is then evaporated iu the weighing glass until 

 the residue no longer flows readily, after which it is dried one hour longer in a water 

 jacket. After cooling, it is weighed. 



In the case of sweet wines (containing over 5 grams of sugar in lOOcc.), 50cc. are 

 taken in a good-sized flask, some sand added and a sufficient quantity of powdered 

 slacklime, and heated with frequent shaking in the water bath. Aftet cooling, 

 lOOcc. of 96 per cent, alcohol are added, the precipitate which forms allowed to 

 -eparate, the solution filtered, and the residue washed wit"h alcohol of the same 

 strength. The alcoholic solution is evaporated and the residue treated as above. 



In regard to the performance of the official method, as given above, 

 Dr. Barth 1 adds the following commentaries and cautions : 



In case the residue from the first evaporation with lime becomes entirely dry it 

 should bo moistened with a little alcohol, the residue removed from the sides of the 



1 Die \\Viiiaiialyst>, p. 17. 



