ze. 
DISTILLATION OF STUMPWOOD. 98 
or air spaces, the weight decreasing as the cubical content increases. 
An increase of about 10 per cent is said to result from reducing 
average cordwood to the size in which the wood making up the 
samples used in this work was piled and measured, from which 
it would appear that the weights per cord on which the yields are 
computed should be increased by 10 per cent. Owing, however, to 
the irregular shape of the pieces of stump cordwood and the care 
observed in piling the reduced wood closely, it is believed that the 
observed weights are not essentially lower than the average weight 
of a commercial cord of western yellow-pine stumpwood of corre- 
sponding quality. In support of this it was found that of the 3 
cords of stumpwood from near Deary, Idaho, piled and measured 
in the field, when corded again after having been reduced to the 
size in which they were used in the retort, one measured an even 
cord, one 19 per cent less than a cord, and the third 10 per cent 
more than a cord. It seems unnecessary, therefore, to use other 
than the observed weights in calculating results. 
The retort distillations were made on charges of known weights, 
varying from 150 to 200 pounds, depending on the nature of the 
wood. The distillation products were measured in liters per charge 
and the yields reported in gallons per cord. This basis of state- 
ment was selected in preference to the more exact unit-of-weight 
basis, the ton, for example, because of the difficulty of estimating 
the quantity of the several classes of wood on a given acre and 
applying the results to the problems in hand on other than the 
cord basis. The yields can be quickly figured to the ton basis from 
the data given in Table 14. 
APPARATUS. 
In principle, the apparatus (figs. 3 and 4) is essentially an oil- 
jacketed retort (@) in which high-flash cylinder oil, heated to the 
desired temperature, is circulated through closely spaced heating 
coils (6, c, and d) within the retort. The coil system of jacketing 
is preferable to a double shell in that it insures a positive flow of 
the heated oil, and, by dividing the coils into sections, prevents an 
excessive drop in temperature between the incoming and outgoing 
oil. A 3-inch layer of asbestos lagging and pipe covering of the 
same material protects the retort and exterior piping against ex- 
cessive radiation. A coarse wire-gauze screen placed on the jacket 
coils facilitates removal of the charcoal. 
The motor-driven oil pump (/) takes oil from the overflow bamile 
(g) and discharges it through the gas-fired oil heater (e) into the 
a coils (6 and c), from the other end of which it flows back 
into the tank (g). This circulation is maintained with the jacket oil 
as it comes from the heater and is held at 260° C. as registered on 
