WINES. 343 



ether-alcohol, and titrated. (The solution of acetate of potash must be neutral or 

 acid. The addition of too much acetate of potash may cause the retention of some 

 bitartrate in solution.) It is best on the score of safety to add to the filtrate from 

 the estimation of the total tartaric acid a further portion of 2 drops of acetate of 

 potash to see if a further precipitation takes place. 



In special cases the following method is recommended for a control 

 over the other : 



Fifty cc. of wine are evaporated to the consistency of a thin sirup (best with the 

 addition of sand), the residue brought into a flask by means of small washings of 96 

 per cent, alcohol, and with continual shaking more alcohol is gradually added, until 

 the entire quantity of alcohol is about lOOcc. The flask and contents are corked 

 and allowed to stand 4 hours in a cool place, then filtered, and the precipitate 

 washed with 96 per cent, alcohol ; the filter paper, together with the partly floccu- 

 lent, partly crystalline precipitate, is returned to the flask, treated with 30cc. warm 

 water, titrated after cooling, and the acidity reckoned as bitartrate. The result is 

 sometimes too high, if pectinous bodies separate out in small lumps, inclosing a small 

 portion of free acids (this error may, however, be avoided by the addition of sand 

 and thorough shaking). In the alcoholic filtrate the alcohol is evaporated, O.Scc. of 

 a 20 per cent, potassic acetate solution added, which has been acidified by a slight 

 excess of acetic acid, and thus the formation of bitartrate from the free tartaric acid 

 in the wine facilitated. The whole is now, like the first residue of evaporation, 

 treated with (sand and) 96 per cent, alcohol, and carefully brought into a flask, the 

 volume of alcohol increased to lOOcc., well shaken, corked, allowed to stand in a cold 

 place 4 hours, filtered, the precipitate washed, dissolved in warm water, and ti- 

 trated, and for 1 equivalent of alkali 2 equivalents of tartaric acid are reckoned. 

 This method for the estimation of the free tartaric acid has the advantage over the 

 former of being free from all errors of estimation by difference. 



I have preferred making the qualitative test for free tartaric acid 

 separately from the bitartrate estimation, and for the latter I have used 

 essentially the first method given, omitting, of course, the i)arallel pre- 

 cipitation with the addition of acetate of potash, modifying it by using 

 only SOec. of the alcohol ether solution for the precipitation and allowing 

 it to stand over night. The titration is nicely performed with phenol- 

 phthaliue and decinornial soda with white wines ; Ice. decinormal soda 

 corresponding to .0188 grams of potassic bitartrate. In the case of 

 dark colored wines I passed them first through a small amount of bone- 

 black, afterwards washing the bone-black thoroughly, so as to avoid the 

 presence of coloring matter in the tartar precipitate. 



SACCHARINE MATTER. 



For the estimation of the saccharine matter use was made of the De- 

 partment method of employing Fehling's solution, already referred to 

 under malt liquors. The Germans usually employ the gravimetric esti- 

 mation, with Soxhlet's modifications, but I believe the other to be fully 

 as accurate, and much more convenient. The wine should be evap- 

 orated about one-third to remove the alcohol, and carbonate of soda 

 added to neutralize the acid. In the case of dark colored wines it is nec- 

 essary to decolorize and clarify them by the use of subacetate of lead or 

 bone-black. If much excess of lead is used it should be removed with 

 sulphate of soda, and if bone-black is used the first portions filtered 

 should be rejected. The amount of reduction is calculated as dextrose. 



