210 FOREST PRODUCTS 



run into cooling ovens located immediately in front of the retort house in 

 the open air. The first cooling oven is about 8 to lo ft. from the charring 

 oven and the second cooling oven about an equal distance beyond the 

 first cooHng oven. The accompanying photographs show the arrange- 

 ment of the cooling ovens in relation to the retort house. The cooling 

 ovens appear to be the same in size, shape and construction as are the 

 ovens themselves. However, the sides are only of ]%-in. steel and usually 

 there are doors at both ends. There are no bottoms to these cooling 

 ovens as they rest directly on the ground. Dirt is piled around the base 

 to prevent the admission of air. 



The cars with the heated charcoal, after the distilling process, are 

 rolled directly into the first cooling oven. As soon as the air is admitted 

 on the opening of the doors, the charcoal bursts in flame and as soon as 

 possible after the cars are rolled into the cooling oven the doors are 

 hermetically sealed, so that the charcoal will cool slowly. The charcoal 

 is left for twenty-four hours in the first cooling oven, twenty-four hours 

 in the second cooling oven, then is left at least forty-eight hours in an 

 open shed or in the open air, and after being loaded on the freight cars it 

 is left standing for at least twelve hours before shipping. This means 

 a total of one hundred and eight hours from the time of heating to the 

 time of leaving the yard. A government regulation prescribes this pro- 

 cedure because " punky " knots hold fire for a long time in the charcoal 

 and it is necessary that these extreme precautions be taken to prevent 

 burning of the cars. 



In some of the plants, an outlet pipe is used near the top of the 

 cooling oven to permit the escape of the acid fumes. It is claimed by 

 some that this saves the eating of the iron by these fumes. 



Still House. 



The provision for re-distilling the pyroligneous liquor is usually 

 housed in the old plants along with the cylindrical retorts, but in the 

 more modern oven plants the apparatus is placed in a separate fire- 

 proof building, usually in close proximity to the power-house or in con- 

 nection with it. 



The equipment of the still house consists principally of the settling 

 tubs, neutralizing tubs, storage tubs, steam pans, copper and iron stills, 

 condensers, fractionating column, etc., required for the three principal 

 distillations previously described. Although the equipment in some 

 small details may vary in each plant, the general process of separating 



