390 FOOD AND FOOD ADULTERANTS. 



(2) A slight excess of sodic carbonate is added to the filtrate from (1). Two cubic 

 centimeters of a solution of plumbic subacetate are added to 40cc. white wine and 

 5cc. to 40cc. red wine, the solution is filtered and Ice. of a saturated solution of sodic 

 carbonate added to 21 or 22.5cc. of the filtrate. 



(:?) The kind of apparatus used and the length of the tube are to be given, and re- 

 sults estimated in equivalents of Wild's polaristrobometer with 200inin. tubes. 



(4) All samples rotating more than 0.5 to the right (in 220mm. tubes, after treating 

 as above), and showing no change, or but little change, in their rotatory power after 

 inversion, are to be considered as containing unferrnen ted glucose (starch sugar) resi- 

 due. 



(5) Rotatory power of less than 0.3 to the right shows that impure glucose has not 

 been added. 



(6) Wines rotating between 0.3 and 0.5 to the right must be treated by the alcohol 

 method. 



(?) Wines rotating strongly to the left must be fermented and their optical prop- 

 erties then examined. 



VIII. Sugar. This is to be determined by Soxhlet's or Knapp's method. The 

 presence of unfermented cane sugar is to be shown by inversion, &c. 



IX. Potassic bitartrate. The determination of potassic bitartrate as such is to be 

 omitted. 



X. Tariaric, malic, and succinic acids. (1) According to Schmidt and Hiepe's 

 method. 



(2) Determination of tartaric acid according to the modified Berthelot-Fleury 

 method. 



(3) If the addition of 1 gram finely powdered tartaric acid to 100 grams wine pro- 

 duces no precipitate of potassic bitartrate, the modified Berthelot-Fleury method must 

 be employed to determine free tartaric acid. 



XI. Coloring matter. (1) Only aniline dyes are to be looked for. 



(2) Special attention is to be paid to the spectroscopic behavior of rosaniline dyes, 

 as obtained by shaking wines with amyl alcohol before and after saturation with 

 ammonia. 



(3) A qualitative test for alumina is not sufficient evidence of the addition of 

 alum. 



XII. Nitrogen. To be determined according to the ordinary method. 



XIII. Citric acid. Presence to be shown by a qualitative test, as baric citrate. 



XIV. Sulphuric acid. To be determined in the wine after adding hydrochloric acid. 



XV. Chlorine. To be determined in the nitric-acid solution of the burnt residue 

 by Volhard's method. 



XVI. Lime, magnesia, and phosphoric acid. These are determined in the ash fused 

 with sodic hydrate and potassic nitrate, the phosphoric acid by the molybdenum 

 method. 



XVII. Potash. Either in the wine ash, as the platinum double salt, or in the wine 

 itself, by Kayser's method. 



XVIII. Gums. Presence shown by precipitation by alcohol ; 4cc. wine and lOcc. 

 96 per cent, alcohol are mixed. If gum arabic has been added, a lumpy, thick, stringy 

 precipitate is produced; whereas pure wine becomes at first opalescent and then 

 flocculent. 



METHODS OF JUDGING PURITY (BeurtheilllUg). 



Part I. 



I. Commercial wines may be defined as follows : (a) The product obtained by the 

 fermentation of grape juice with or without grape skins and stems. (1>) The prod- 

 uct obtained by the fermentation of pure must, to which pure sugar, water, or infu- 

 sion of grape skins has been added. It must contain not more tli:m 1> per cent, 

 alcohol and 0.3 per cent, sugar, and not less than 0.7 per cent, acid, estimated as tar- 



