xii. a, 3 Wells: Destructive Distillation 113 



show a likeness in size, color, specific gravity, and apparent 

 moisture content. 



A separate lot of each kind of woods was kiln-dried until the 

 moisture content seemed uniform. The whole specimen was 

 then placed in a tight container, and from this the daily charge 

 was taken and distilled. From eight to thirteen charges were 

 made from each specimen and specific gravity and moisture de- 

 termination made on each charge- The averages for these de- 

 terminations are found in Table I. The specific gravities were 

 taken by the usual method. The measure of the moisture was 

 not that of the total volatile substance below 108° C, which 

 in many cases would contain oils, but a measure of the volatile 

 part taken up by pure calcium oxide. The determination was 

 made by passing the volatile matter through a tube of calcium 

 oxide, afterward heating the tube for three hours at a temper- 

 ature of 185° C. sufficiently high to volatilize all oils present and 

 yet not to drive off water from the partially slaked lime. 



Destructive distillation was selected as the method for distill- 

 ing the woods, the reason being that it seemed to give the 

 highest yields of the commercial products — methyl alcohol, 

 acetic acid, tars, and charcoal. Steam distillation might have 

 shown interesting results regarding the resinous products 

 obtainable, and this method may be applied later to certain 

 classes of woods that are known to be high in resinous content. 

 The destructive method is that in general use in the distillation 

 of hard-wood waste, and for that reason also it is used here to 

 furnish experimental data of comparative value. 



In determining a laboratory method for the distillation, it 

 seemed advisable to have a temperature control. During 1913 

 experiments were made in this laboratory by utilizing an oil- 

 jacketed retort. In the use of the oil-jacketed retort a heavy 

 hydrocarbon oil was heated and kept in circulation by the aid 

 of an electrically controlled Kinney pump, which was connected 

 to the retort so that it supplied cold oil from the storage tank 

 and also accelerated the circulation of the hot oil about the 

 retort. Coils of various sizes and forms were tried as heating 

 surfaces for the oil. The most satisfactory surface seemed to 

 be that of a piece of iron pipe 17 centimeters long by 13.5 centi- 

 meters in diameter, capped at both ends, the caps being bored 

 to accommodate a 1-inch circulation pipe. 



The heat was furnished by two Meker burners connected to 

 the laboratory gas supply. The loss of heat by radiation was 

 cut down by placing a heavy shell of asbestos cement over the 



