218 VINEGAR, CIDER, AND FRUIT- WINES. 



Concentrated hydrochloric acid colors wood rose color to violet 

 red and then rapidly destroys it. Dilute hydrochloric acid, on 

 heating, forms sugar ; but, according to Zetterlund, the quantity 

 of absolute alcohol obtainable in this manner is very small, 

 amounting to about 2.3 per cent, of the weight of the wood.* 

 By macerating wood with dilute hydrochloric acid at an ordinary 

 temperature, the cellulose is not changed, but the so-called lignin 

 seems to be dissolved. By forcing dilute hydrochloric acid by a 

 pressure of two atmospheres into trunks provided with the bark, 

 and subsequent washing out in the same manner with water, and 

 drying by means of a current of air at 98.6 F., wood acquires 

 great plasticity. In a moist state wood thus treated can be 

 pressed together to one-tenth of its original volume. 



Hydriodic acid reduces the wood to several hydrocarbons, 

 water being formed and iodine liberated. 



Concentrated nitric acid, or, still better, a mixture of it and 

 sulphuric acid, converts cellulose, for instance, cotton, into gun- 

 cotton ; wood is colored yellow and partially dissolved. Dilute 

 nitric acid, for instance, of 1.20 specific gravity, has no effect in 

 the cold, and but little when heated. 



By bringing cellulose in contact with dilute aqueous solutions 

 of alkalies, it is colored blue by iodine, and consequently a starch- 

 like substance is formed, but no humus-like bodies ; from wood 

 only the lignin is extracted, the woody fibre remaining unchanged. 

 By heating with strong alkaline lyes, or, still better, by fusing 

 with solid caustic alkalies, acetic acid is, according to Braconnot, 

 first formed and then oxalic acid. The latter acid is frequently 

 obtained by this process. 



On heating shavings with sodium sulphide an abundant quan- 

 tity of acetic acid (sodium acetate) is formed ; the addition of 

 sulphur to caustic soda seems to have the effect of preventing the 

 formation of oxalic acid. 



< According to prior experiments by Bachet, it is, however, claimed that 

 up to 23 per cent, of sugar can be obtained from wood by boiling 10 to 12 

 hours with water containing one-tenth of hydrochloric acid. 



