ALCOHOLS. 311 



last quantities of water, amounting to about 14 per cent., cannot U 

 removed by simple distillation, but may be separated by mixing the 

 alcohol with half its weight of calcium oxide, which combines with 

 the water to form calcium hydroxide, from which the alcohol may 

 now be separated by distillation. 



FIG. 40. 



Cf> 



Liebig's condenser with distilling-flask. 



The alcohol thus obtained, and containing not more than 1 per 

 cent, of water, is known as pure, absolute, or real alcohol. The 

 alcohol of the U. 8. P. contains 91 per cent, by weight, or 94 per 

 cent, by volume of real alcohol, and has a specific gravity of 0.820 

 at 15 C. (59 F.). The diluted alcohol is made by mixing equal 

 volumes of water and alcohol, and has a specific gravity of 0.936; it 

 is identical with the proof-spirit of the U. S. Custom-house and 

 Internal Revenue service. 



Pure alcohol is a transparent, colorless, mobile, and volatile liquid, 

 of a characteristic rather agreeable odor, and a burning taste ; it boils 

 at 78 C. (172 F.), has a specific gravity of 0.797, is of a neutral 

 reaction, becomes syrupy at 110 C. ( 166 F.), and solidifies at 

 130 C. (202 F.); it burns with a non-luminous flame; when 

 mixed with water a contraction of volume occurs, and heat is liber- 

 ated ; the attraction of alcohol for water is so great that strong 

 alcohol absorbs moisture from the air or abstracts it from membranes, 

 tissues, and other similar substances immersed in it ; to this property 

 are due its coagulating action on albumin and its preservative action 



