WINES. 357 



such a contamination should never be forgotten, especially if any of 

 the symptoms of lead poisoning have been produced by a suspected 

 sample. The search for mineral constituents in wine presents no diffi- 

 culties and need not be further dwelt upon. 



Gummy substances are sometimes added to watered wines to make 

 up for their deficiency in extract. Gum arabic, or commercial dextrin, 

 have been used for this purpose. The addition may be detected by the 

 following method, taken from the German Commission: "lOcc. of 95 per 

 cent, alcohol are added to 4cc. of wine and the whole well shaken; if 

 gums are present the liquid becomes milky and does not clear up com- 

 pletely even after standing several hours. The precipitate formed 

 adheres in part to the sides of the glass, and forms lumps. In genuine 

 wines flakes form after a short time, which subside and remain rather 

 loose. For a more exact test the wine should be- evaporated to a sirup, 

 extracted with alcohol, and the insoluble part dissolved in water. This 

 solution is treated with Ice. hydrochloric acid, heated under pressure 

 for two hours and the reducing power ascertained with Fehling's solu- 

 tion. With genuine wines no considerable reduction is obtained in this 

 way." I have made no trial of this method. 



The adulteration of wines by substituting for it, wholly or in part, the 

 fermented juices of other fruits, such as cider, is a matter difficult of 

 detection. The presence in such wines of malic acid and the absence of 

 tartaric was formerly considered a sufficient proof of the addition, but 

 it is found that in bad years malic acid often predominates in grape 

 juice, and on the other hand various causes may greatly reduce the 

 content of bitartrate of potash, or even cause it to entirely disappear. 

 The proof of such addition by chemical means rests chiefly upon con- 

 elusions drawn from the general composition of the sample analyzed. 

 Often the taste or odor of the residue of evaporation of the sample it- 

 self or of the distillate will give some clew to such addition. Often the 

 recognition of free tartaric acid in such wines will condemn them as 

 artificial, for natural wines contain a very small amount, if any, of the 

 free acid; according to the German Commission never more than one- 

 sixth of the total free fixed acids. Tartaric acid is often added also to 

 wines which have been deprived of part of their normal acidity by the 

 addition of water or sugar solutions. The qualitative determination is 

 as follows: 



To 20 or 30cc. of wine is added precipitated arid finely powdered bitartrate of 

 potash, the whole well shaken and filtered after standing an hour. To the clear 

 solution is added 2 or 3 drops of a 20 per cent, solution of acetate of potash and the 

 whole allowed to stand twelve hours. The shaking and standing of the solution must 

 take place at as nearly as possible the sarne temperature. If at the end of this time 

 any considerable precipitate has separated out, the quantitative estimation should be 

 undertaken. 



Foreign coloring matters are frequently added to red wines, either to 

 brighten and improve the color obtained from the grapes, or, more fre- 

 quently, to cover up the effects of previous dilution. These colors may 

 4450 No. 13, pt, 3 7 



