§ 142. WINE. 283 



the precipitate obtained as above with alcohol ; the re- 

 mainder, after subtracting this, may be reckoned as calcic 

 malate, although it may contain a little succinate. 



The acetic acid, malic acid, and tartar, taken together, 

 correspond very nearly to the amount of soda used in Ic^ 

 to determine the free acid, each equivalent of tartar neu- 

 tralizing one equivalent of soda. 



0. Free sulphuric acid, if present in the wine under 

 examination, may be detected and determined in the same 

 manner as directed in § 138, h. 



p. Total alkalies. — These may be estimated in the ash 

 obtained in c, or in the following manner. 



To the remaining 30 c.c. of the filtrate from the pre- 

 cipitate by alcohol in /, add 5 c.c. of an alcoholic solution 

 of tartaric acid, whose strength is accurately known, let 

 the mixture stand several days, and titrate 25 c.c. of the 

 clear supernatant liquid with the standard sodic solution ; 

 the rest of the j^otassa, not precipitated in ?, and the soda, 

 have crystallized out, with an equivalent quantity of the 

 tartaric acid that was added; this quantity of acid will be 

 represented by the difference between the amount of sodic 

 solution used in this trial, and that which would be re- 

 quired to neutralize the free acid already in the solution 

 (see ?), plus the 5 c.c. of tartaric acid added. For each 2 

 c.c. of this difference estimate 0.0471 grm. of potassa and 

 add it to the amount in the tartar obtained in I. 



The average composition of v/ine, according to Messier, 

 who examined a large number of European wines, is as 

 follows: Alcohol, 7- 10° 1^; Sugar, 0.1 _ 0.2° |„; Free acid, 

 estimated as tartaric, 0.4 - 0.8°| „ ; Malic acid, - 0.3° |„ ; 

 Acetic acid, 0-0.3°|^; Tannic acid, 0.02 - 0.05° |„. 

 Total dry substance in solution, 1.5 — 2°!^. 



