102 
formly as possible all around the outside of the retort. As the tem- 
perature inside the retort increases from 100° to 700° F., the liquid and 
some of the solid portions of the wood are converted into gas and 
vapor, and pass out of the retort through a copper "worm" inclosed 
in a cold-water tank and are collected in the form of wood-gas, naptha, 
acid, and oil. When the oil ceases to run, the fires under the retort 
are j>ut out, the bitumen is drawn off through, a tube coming from the 
bottom of the retort, and the latter is then allowed to cool off. As soon 
as possible, therefore, the doors of the retort are opened and the char- 
coal raked out. The operation is thus finished, and the retorts are 
ready for a fresh charge. 
Timber and lumber which is to be treated with this oil must be first 
prepared to receive it. Timber is taken directly from the river by large 
derricks, is landed on the wharf, is stripped of its bark, and then ex- 
posed to the sun for a week or ten days to dry. At the end of this 
time it is placed (one stick at a time) on trucks, is rolled into the car- 
bonizing cylinder, is there exposed from about ten to twenty minutes 
to an intense radiated heat, and is then withdrawn charred to a depth 
of one-fourth of -an inch, thoroughly dried to a depth of three-fourths of 
an inch, and thoroughly heated to a depth of several inches. 
The carbonizing cylinder consists of a wrought-iron cylindrical tube 
about 21 feet long by 28 inches in diameter, set in a brick furnace, 
fired at the side and midway of its length, the cylinder being brought 
to a proper and uniform heat by means of a wood fire, the heat and 
flames of which pass by vertical and horizontal flues along and all 
around the cylinder. The cylinder is further provided with a small rail- 
road track and iron carriage on the inside, for the convenient handling 
of the timber. Sawn lumber is not usually charred, but is sometimes 
kiln-dried or semi-charred ; the objection to the charring being that it 
destroys the sharp edges of the lumber. The charring or carbonizing 
of the process, therefore, consists in taking the timber and subjecting it 
to a dry radiant heat within the suitable cylindrical surfaces in such 
manner as to drive out of the timber most of its sap and albuminous 
matter (ordinarily about five pounds to the square foot), drying the 
inside of the timber, charring its outside, and leaving the wood with its 
j)ores open and in condition to be completely filled with the wood-creo- 
sote oil thereafter applied to it. 
Charred timber, once thoroughly carbonized, will not crack under 
subsequent exposure to the sun and air. If further properly treated 
with wood-creosote oil, it will withstand all attacks of atmosphere, 
moisture, and animal life, and will last for years anywhere. 
This process for carbonizing and creosoting timber is such that it does 
not injure the fiber of the interior of the wood. It is one of the sim- 
plest, cheapest, quickest, most effective, and most successful processes so 
far known for artificially seasoning and preserving wet or green timber, 
in cases where the want of time or money do not allow a thorough natu- 
