16 BULLETIN 1308, U. S. DEPARTMENT OF AGRICULTURE 
ered into the distilling flask already containing To cubic centimeters 
of kerosene. The pipette is clamped vertically with its tip just below 
the surface of the kerosene and allowed to drain five minutes. The 
contents of the flask are then distilled to decomposition at a rate 
of not more than 2 drops per second from the condenser into the 
tar-acid separatory funnel. The distillate in the funnel is thor- 
oughly shaken with 25 cubic centimeters of sulphuric acid solution, 
allowed to stand at least one-half hour, and then measured at 25° C. 
after the sulphuric acid has been thoroughly drained off. It is next 
extracted with three portions of sodium-hydroxide solution with a 
minimum period of rest between each agitation and separation as 
follows: (a) 100 cubic centimeters and three hours; (b) 80 cubic 
centimeters and two hours; (c) 60 cubic centimeters and one hour. 
After thorough draining it is again measured at 25° C. The differ- 
ence between the two measurements multiplied by 4 represents the 
volume percentage of total phenols in the sample. 
Precautions. — No loss of the upper layer on the removal of stop- 
pers or from leaky stopcocks may be permitted. All insoluble matter 
at the interface should be left with the upper layer in each separa- 
tion. If such insoluble matter is of significant volume at the end, 
about 5 cubic centimeters of sulphuric acid solution may be added, 
the tube well rotated in a vertical position between the palms of the 
hands, left at rest 15 minutes, and then drained for measurement. 
All drainages should be as complete as possible, and all readings 
should be made while the funnel is actually within a water bath of 
the prescribed temperature, as, for example, an ordinary liter 
cylinder. 
PROCEDURE FOR SAPONIFIED CRESOL SOLUTIONS 
The graduated cylinder is filled above the mark with the sample 
and a thermometer is used as a stirrer while the temperature is 
brought to 25° C. After withdrawal of the thermometer and the 
elimination of air bubbles all froth is removed with filter paper and 
the level of the liquid adjusted to the mark by aid of a pipette. The 
contents of the cylinder are completely transferred to the distilling 
flask by rinsing with 75 cubic centimeters of kerosene in successive 
portions; then 2.5 grains of sodium bicarbonate are added, or more 
if indicated necessary by the excess alkali determination, and the 
contents of the flask are mixed by swirling for one minute. The con- 
tents are then distilled at a rate of not more than 2 drops per second 
from the condenser into the tar-acid separatory funnel until the 
distillate comes over strongly yellow. The distillate in the funnel 
is shaken twice with 10 cubic-centimeter portions of sulphuric-acid 
solution, allowing at least one-half hour between each agitation and 
ensuing separation. After complete drainage of the second acid 
extract the distillate is measured at 25° C. and thereafter handled as 
prescribed in the procedure for cresol, except that the extraction with 
100 cubic centimeters of sodium-hydroxide solution is omitted. 
Precautions. — In addition to the precautions noted in the pro- 
cedure for commercial cresol, special attention is necessary to avoid 
boiling over. The distillation is to be started with a low flame verti- 
cally under one side of the flask. As frothing lessens, the flame is 
moved toward the center, but it is then necessary to watch for a 
sudden, spontaneous increase in the violence of boiling that occurs 
