MANUFACTURE OF WOOD- VINEGAR. 217 



as aluminium and copper soaps, in the interior of the wood by 

 saturating it with soda soap and then with aluminium chloride or 

 blue vitriol, or such as barium phosphate by saturating with 

 sodium phosphate and then with barium chloride,, etc. 



By heating to 212 F. the wood remains unchanged; it 

 yields up only sap constituents. If, however, the temperature be 

 increased, for instance to 392 F., a small quantity of sugar is, 

 according to Mulder, formed from cellulose in a closed vessel, 

 and from wood, according to G. Williams, an acid not yet 

 thoroughly known, methyl alcohol (see further on), an oil boiling 

 between 277 and 421 F. and a small quantity of furfurol. 



In the presence of water, wood in a closed vessel is, however 

 already decomposed at about 293 F., if this temperature be 

 kept up for a long time, for instance, a month, the wood, accord- 

 ing to Sorby, being converted into a lustrous black mass with 

 the formation of acetic acid and gases. 



According to Daubree, pine, when heated for some time with 

 water in an entirely closed vessel to 752 F., is converted into a 

 mass having the appearance of stone-coal and approaching an- 

 thracite in its behavior. Baroulier made similar observations, 

 masses resembling stone-coal being formed by pressing sawdust, 

 stems, and leaves together in moist clay and heating continuously 

 to from 392 to 572 F., so that the vapors and gases could 

 escape only very slowly. 



By avoiding all heating concentrated sulphuric acid converts 

 cellulose into a gum-like body, dextrin, which by diluting with 

 water and long digesting is converted into sugar (starch sugar) ; 

 when heated the wood, however, turns black with development of 

 sulphurous acid and complete destruction. By dilute sulphuric 

 acid cellulose is converted into starch, or at least a starch-like 

 body colored blue by iodine and dextrin. Wood is, however, but 

 little affected by it at an ordinary temperature, while at a higher 

 temperature a certain quantity of sugar (starch sugar) is formed, 

 water being absorbed at the same time. This behavior has been 

 utilized for obtaining alcohol by fermenting the sugar with yeast 

 after neutralizing the acid by calcium carbonate, for instance, 

 chalk. The unattacked woody fibre can be used as material for 

 paper. 



