384 FOOD AND FOOD ADULTERANTS. 



(5) If in samples of wine taken from any business concern adulteration is shown, 

 a bottle of the water is to be taken which was presumably used in the adulteration. 



(6) It is advisable, in many cases necessary, that, together with the wine, a copy 

 of these resolutions be sent to the chemist. 



A. Analytical methods. 



Specific gravity. --In this determination use is to be made of a picnometer, or a 

 Westphal balance controlled by a picnometer. Temperature 15 C. 



Alcohol. The alcohol is estimated in 50-100cc. of the wine by the distillation method. 

 The amount of alcohol is to be given in the following way : In lOOcc. wine at 15 C. 

 are contained n grams alcohol. For the calculation the tables of Baumhauer orHeb- 

 ner are used. 



(The amounts of all the other constituents are also to be given in this way ; in 

 lOOcc. wine at 15 C. are contained n grams.) 



Extract. For this estimation 50cc. of wine, measured out at 15 C., are evaporated 

 on the water bath in a platinum dish (85mm. in diameter, 20mm. in height, and75cc. 

 capacity, weight about 20 grams), and the residue heated for two and one-half hours 

 in a water jacket. Of wines rich in sugar (that is, wines containing over 0.5 grams 

 of sugar in lOOcc.) a smaller quantity, with corresponding dilution, is taken so that 

 1 or at the most 1.5 grams extract are weighed. 



Glycerine. One hundred cubic centimeters of wine (for sweet wines see below) are 

 evaporated in a roomy, not too shallow, porcelain dish to about lOcc., a little sand 

 added, and milk 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 frequent stirring. The solution is poured oft' through a filter, and the 

 residue exhausted by treatment with small quantities of alcohol. For this 50 to lOOcc. 

 are generally sufficient, so that the entire filtrate measures 100-200cc. 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 in the 

 weighing glass until the residue no longer flows readily, after which it is dried an 

 hour longer in a water jacket. After cooling it is weighed. 



In the case of sweet wines (over 0.5 grams sugar in lOOcc.) 50cc. are taken in a 

 good-sized flask, some sand added, and a sufficient quantity of powdered slack-lime, 

 and heated with frequent shaking in the water bath. After cooling, lOOcc. of 96 per 

 cent, alcohol are added, the precipitate which forms allowed to separate, the solution 

 filtered, and the residue washed with alcohol of the same strength. The alcoholic 

 solution is evaporated and the residue treated as above. 



Free acids (total quantity of the acid reacting constituents of the wine). These are 

 to be estimated with a sufficiently dilute normal solution of alkali (at least one-third 

 normal alkali) in 10 to 90cc. wine. If one-tenth normal alkali is used at least lOcc. 

 of wine should be taken for titration; if one-third normal, 20cc. of wine. The drop 

 method (Tupfel method*), with delicate reagent paper, is recommended for the estab- 

 lishment of the neutral point. Any considerable quantities of carbonic acid in the 

 wine are to be previously removed by shaking. Those " free acids " are to be m-k- 

 oned and reported as tartaric acid (C^HeOe). 



Volatile acids. Those are to bo estimated by distillation in a current of steam, and 

 not indirectly, and reported as acetic acid (CaRiOi). The amount of the "fixed 

 acids " is found by subtracting from the amount of " free acids " found, the amount of 

 tartaric acid corresponding to the " volatile acids" found. 



llilnrtnite of potash and free tartaric acid. (a) (Qualitative detection of free tartarie 

 acid: 20-30cc. of the wiuo are treated with precipitated and linely powdered bitar- 

 trate of potash, .shaken repeatedly, filtered oft' after an hour, and 'J-:? drops of a - Ji> 

 per cent, solution of acetate of pota-li added fn the clear filtrate, ,<ind the solution 



