98 DEPARTMENT BULLETIN 1216, U. S. DEPT. OF AGRICULTURE 
furnace. Whatever the method of heating employed, the temperature during 
the entire seven-minute period shall be not less than 950° C. and should be as 
near that temperature as possible. At the end of this period the flame shall 
be removed, the crucible transferred to a desiccator and permitted to cool, after 
which, it shall be weighed. The residue in the crucible after ignition shall be 
reported as "fixed carbon" (that is, coke). 
3. The test shall be conducted in a part of the laboratory free from drafts. 
4. The percentage of coke obtained in accordance with section 2 shall be 
calculated on the basis of the original sample of oil. 
Example. — With a retort distillation of 29 per cent of residue at 355° C, the 
residue containing 28 per cent of fixed carbon : 
„ . . ., 29X28 t 
Coke in oil = 1r>f) =8.1 per cent. 
62. METHOD OF TEST FOR DISTILLATION OF CREOSOTE 
OIL 
(A. S. T. M. standard method (4), serial designation D*246-27 T) 
This is the same method as given under method No. 52 ( see p. 77 i . method 
of test for distillation of tars and tar products. 
63. METHOD OF SAMPLING AND TESTING WOOD BLOCK 
1. Sampling. — Ten blocks shall be taken as a sample. 
2. Measurement and weight. — Each block is measured for length, breadth, and 
thickness and the total volume in cubic inches of the 10 blocks is computed. 
The whole number of blocks are weighed to the nearest gram, or one-eighth 
ounce, and the weight in pounds per cubic foot of the block is calculated. 
ANALYSES 
3. The sample for analysis shall be obtained by boring into the end grain of 
all the blocks, according to Figure 43. 
4. Moisture. — Take 25 grams of borings and place in a 250-cubic-centimeter 
Erlenmeyer flask and pour on about 75 to 100 cubic centimeters of water- 
saturated xylol. Connect the flask to a condenser with a short tube and distill 
off the xylol rapidly, continuing the distillation to near dryness, collecting the 
distillate in a cylinder graduated to tenths of a cubic centimeter. The distillate 
will consist of xylol and water. The water will separate and collect in the 
bottom of the cylinder, where the amount may be read off and calculated in 
percentage. 
5. Oil.— Take a C. S. & S. capsule or a folded hard paper (C. S. & S. No. 575) 
which has been previously extracted with benzol and dried. Weigh into this 
about 5 to 10 grams of borings, making the weighing in a weighing bottle. 
The capsule and borings are then extracted in some suitable extraction appa- 
ratus, using benzol as the solvent until the washings run through practically 
colorless. Chloroform is then substituted for benzol as the solvent until the 
washings again run through practically colorless. The extraction removes from 
the borings water, rosin, and oil. 
6. Rosin. — The benzol and chloroform washings are united and shaken out in 
a separatory funnel with a 3 per cent solution of sodium carbonate, or pref- 
erably sodium hydrate, using about three 100-cubic-centimeter portions. The 
alkali washings are drawn off and united, acidulated with sulphuric acid, and 
then shaken out with petroleum ether. The ether washings are united and 
filtered into a tared flask, evaporated on a hot plate, and the residue dried in 
the oven. This residue represents mainly rosin, although there is a possibility 
that it may contain some tar acids from the oil. The amount of oil with which 
the block is impregnated is obtained by taking the percentage of extract as 
determined under " oil " and subtracting from it the percentage of water plus 
rosin. 
