Hed Charcoal — Distilled Products of Wood. 153 



more rapidly in proportion than a forest of large trees. The process 

 of assimilation may be compared to that observed in animal life, 

 where the structures are formed in early life. 



Red Charcoal. 



613. About 1836, a method was introduced in France for semi- 

 carbonizing wood, by placing it in chambers at the mouths of fur- 

 naces, and exposing it to a heat by which the water and acetic acid 

 are expelled, and the combustible gases left. This product, some- 

 times called " terrified wood," is used in melting pig-iron for cast- 

 ing and other purposes. It ignites freely, does not impair by keep- 

 ing, and bums with a copious flame and intense heat. It is said 

 for certain purposes to afford 30 per cent more of heat than fully- 

 burned charcoal. The process being stopped just at the point 

 where carbonization begins, the wood retains its texture and ap- 

 pearance ; it may be split, cut, or sawed, but has lost its strength, 

 and is of a reddish brown color. 



Distilled Products of Wood. 



614. In all forms of kilns the volatile products may be condensed 

 and saved. The smoke is drawn from the kilns and condensed. The 

 methylic alcohol or wood-spirit is first separated by distillation ; the 

 residue of dilute acetic acid is then neutralized with lime, and 

 evaporated to dryness. About two gallons of the wood spirit are 

 produced from the smoke of a cord of hard wood, and when puri- 

 fied it may be applied to all chemical uses for which common alco- 

 hol is employed, but chiefly in making paints and varnishes. After 

 the spirits are distilled out, the residue, with lime added, yields 

 about 200 pounds to the cord. It is chiefly used in making white 

 lead. 



615. Besides these, a large number of chemical products may be 

 derived from the distillation of wood, having use in calico printing, 

 and in other industries, and the value from a given quantity of 

 wood from these sources, at present prices, amounts to more than 

 twice that of the charcoal made at the same time. The gases re- 

 maining in this process have not much illuminating power, but are 

 used in supplying a part of the heat required for the evaporation. 



