252 GLITCIC ACID. 



4 per cent, comes very near the 3' 7 per cent, given 

 by the above-mentioned chemists. 



If glucic acid be really present in wine, and the 

 wine be treated in the manner described (p. 248), the 

 acid will be found in the liquid which has been filtered 

 from the lime salt precipitated by alcohol. If the 

 glucic acid be saturated with caustic potassa, it com- 

 bines with it and forms a neutral salt, which is inso- 

 luble in alcohol ; but if, as was the case here, it be 

 saturated with chalk, an acid salt is formed, from 

 which no precipitate can be formed by alcohol. The 

 alcoholic liquid, separated from the neutral salt, con- 

 tains not only all such acid glucate of lime as may be 

 present, but likewise the sugar of the wine, nearly all 

 the tannic acid, and such other substances as, under 

 these circumstances, are soluble in alcohol. 



The alcohol was distilled, the residue dissolved in 

 water, and precipitated with basic acetate of lead, 

 which gave rise to a copious precipitate. 



After the lead had been removed from the liquid, 

 which was drawn off, the presence of sugar was indi- 

 cated by the copper test. 



The precipitate of basic acetate of lead was sus- 

 pended in water, sulphuretted hydrogen conducted 

 through it, the liquid warmed in order to expel sul- 

 phuretted hydrogen again, milk of lime added in order 

 to separate the tannic acid which was present in large 

 quantity as a basic lime salt. The liquid was filtered, 

 carbonic acid conducted through it, then warmed, and 



