io8 FOREST UTILIZATION 



C. Further treatment. 



The gases, condensed to a liquid a large proportion of which is 

 water, are then treated with lime. Lime neutralizes the pyrolig- 

 neous acid, forming acetate of lime. 



The liquid is then redistilled, wood alcohol going over first, water 

 next. The residue is boiled down in open pans to the consist- 

 ency of a sugar, the acetate of lime of commerce. From it acetic 

 acid and its salts are derived in chemical works. 



D. The output. 



One hundred volumes of air dry wood furnish up to forty-eight 



volumes of pyroligneous acid. 

 One and three-quarters cords of beech yield 2,650 pounds of 



liquids, 25 gallons of tar and 700 pounds of charcoal. 

 The 2,650 pounds of liquids furnish 200 pounds of acetate of lime 



and 9 gallons of 82% wood alcohol. 



E. Use : Acetate of lime is used by the chemical industry in the 



manufacture of acetic acid and of the salts of acetic acid. 

 Wood alcohol is used largely in the manufacture of varnishes, 

 dyes, celluloid and especially for heating. It is poisonous. 



§ XXXVI. TRUE OR AETHYL ALCOHOL AND ITS MANUFACTURE. 



A. Principle underlying the process. 



Wood boiled under pressure in the presence of acids yields sugar 

 (dextrose). This sugar, freed from the acid admixed, is allowed 

 to ferment under the influence of yeast and changed into aethyl 

 alcohol. 



B. Raw material : 



Cottonwoods, linden, yellow poplar are said to be superior to the 

 . heavy hardwoods as well as to conifers. Possibly chestnut wood, 

 from which the tannin is withdrawn in tannin extract factories, 

 may answer as a raw material. Unless sawdust is available, the 

 wood is prepared, sawed and pounded as if it were to be used in 

 the manufacture of chemical fibre. 



C. Process : 



The acid used does not enter into any chemical combination with 

 the wood. It merely acts by its presence and is said to be most 

 efficient when in statu nascendi. Sulphuric acid, sulphurous 

 acid, hydrochloric acid or a mixture of these and similar acids 

 are used. 



The temperature of the lead-coated vats containing acid and vifood 

 is gradually raised to about 250° F. Hydraulic pressure is also 

 applied, either before or after the boiling process. As a matter 

 of fact, the partial conversion of cellulose into starch seems to 

 be due to pressure— not to boiling. The acid is then neutralized 

 and the temperature reduced to about 85° F. By the addition of 

 yeast (fed on phosphates of potash and of ammonia) a violent 

 fermentation of the sugar is started, ending within thirty-six 



