566 



FORESTRY AND IRRIGATION 



December 



wooden strips 4 inches wide and 

 placed about one inch apart. Under 

 this grating water is boiled by a fire 

 placed on the ground under the iron 

 bottom, and the chipped bark rests on 

 the grating. The grating thus keeps 

 the bark out of the water and the 

 steam alone, as it rises through the 

 still filled with bark, extracts the oil. 



After filling the still with finely 

 chipped bark the top is placed on and 



iron water pipe. In some cases it is 

 bent to form a connection with the 

 side of the vat ; in other cases a wood- 

 en plug is wedged into the opening of 

 the vat, through which an auger hole 

 is bored, taking a right angle turn in 

 the center of the block of wood. In 

 the other side of the plug, at right 

 angles to the side against the vat, the 

 straight pipe is inserted, thus obviating 

 the necessity of bending the pipe and 



Fig. I. Black Birch Tree Peeled for Oil. 



held firmly in position by sticks and 

 wedges. The steam rising through 

 the grating and permeating the bark 

 extracts and vaporizes the oil and car- 

 ries it to the top and through an iron 

 pipe or worm. This "worm," how- 

 ever, is not coiled as in the condensers 

 of liquor stills, but is a simple straight 



plugging the opening in the vat around 

 the pipe. 



The iron pipe is laid in a trough 

 through which the water from a brook 

 is deflected. The steam and vaporized 

 oil passing in mixture into the worm 

 is condensed there and the resulting 

 water and oil trickles by drops into a 









