182 CHEMISTRY. 



Quantity of Alcohol in Wine. 



To ascertain the quantity of alcohol in wine, 



Add to one part, by measure, of the wine to be 

 examined, one part of concentrated solution of sub- 

 acetate of lead ; a dense insoluble precipitate will en- 

 sue, which is a combination of the test liquor with the 

 colouring, extractive, and acid matter of the wine. 



Shake the mixture for a few minutes, pour the 

 whole on a filter, and collect the filtered fluid, which 

 last contains the spirit and the water of the wine, 

 together with a portion of the subacetate of lead. 



Add, in small quantities at a time, to this fluid, 

 warm, dry, and pure subcarbonate of potash, which 

 has been previously freed from water by heat, until 

 the last portion thus infused remains undissolved. 

 The alcohol or spirit contained in the fluid will thus 

 be separated; for the subcarbonate of potash ab- 

 stracts from it the whole of the water with which it 

 was combined ; the spirit of the wine forming a dis- 

 tinct stratum, which floats on the aqueous solution of 

 the alkaline salt. 



If the experiment be performed in a glass tube, 

 from half an inch to two inches in diameter, and gra- 

 duated into 100 equal parts, the per centage of the 

 spirit in a given quantity will be at once perceptible, 

 and in this manner the strength of any wine may be 

 examined. 



