14 
BULLETIN 1308, U. S. DEPARTMENT OF AGRICULTURE 
Table 3. — Data on determination of total phenols in J^O cubic-centimeter samples 
of saponified cresol solution H B in experiment 6 
Experiment number 
Other additions besides kerosene 
Maxi- 
mum 
tempera- 
ture 
Apparent 
percent- 
age of 
phenols 
1.6 c. c. of NaOH sol. (1 c. c. = 0.516 g. NaOH). 
°C 
280 
Per cent 
44 8 
b 
Ditto, plus 2 g. NaHC03 
48 8 
Ditto, plus 4 g. NaHCOj 
277 
280 
260 
281 
320 
50 1 
d„. 
4 g. NaHC03 only; no NaOH 
50 
e . - 
do 
48 
f 
Ditto, but using "toopel" kerosene 
50 1 
g 
4 g. NaHCOs; 5 c. c. medicinal mineral oil 
49 9 
The data of Table 3 show that sodium bicarbonate is effective in 
neutralizing an excess of sodium hydroxide. The original saponified 
cresol solution was made to contain a slight theoretical excess of 
alkali (4.23 weight per cent against 4.03 theoretical), but the further 
addition of a 50 per cent excess of sodium hydroxide was taken care 
of by sodium bicarbonate when enough was present. 
Experiment 6 (e) was purposely run to a low maximum tempera- 
ture, which was evidently insufficient to expel all phenols. In experi- 
ment 6 (f ) the kerosene had been previously " topped " to a tempera- 
ture of 210° C. and the lower boiling fraction of about 24 per cent 
discarded, but no greater recovery of phenols was effected by the use 
of this material. Except for experiment 6(e) the maximum tempera- 
ture noted was not a matter of choice, but was the maximum obtain- 
able after which the thermometer began to drop owing to the high 
viscosity of the residue which cut down the rate of heat transfer and 
led to charring on the bottom of the flask. But evidently a nearly 
quantitative recovery of phenols is effected if the distillation is car- 
ried to this point. 
In further work it seemed better to sacrifice a certain degree of pre- 
cision by reducing the volume of the sample to 25 cubic centimeters, 
thus expediting the distillation, rendering the expulsion of phenols 
more certainly complete and eliminating the necessity for making a 
correction, always an undesirable feature in a practical method of 
analysis. Using two portions of 10 cubic centimeters each of sul- 
phuric-acid solution for the acid extraction, the total volume of ex- 
tract will be practically the same as that resulting in the assay of 
commercial cresol and will be automatically corrected for by the 
other errors of opposite sign inherent in the process, as in the assay 
of commercial cresol. 
EXPERIMENT 7 
Saponified cresol solution H B, 25.15 cubic centimeters, was dis- 
tilled from a 200 cubic centimeter flask with 75 cubic centimeters 
kerosene and 2.5 grams sodium bicarbonate. Except for two experi- 
ments a thermometer was not used, for it was found that the maxi- 
mum temperature was always above 280° C. and that it was surely 
passed if the distillation was continued until the distillate began to 
come over strongly yellow owing to incipient charring of the residue. 
The distillate was extracted in the tar-acid funnel with two portions 
of 10 cubic centimeters of sulphuric-acid solution of specific gravity 
1.505. The second extraction removed not more than 0.20 cubic 
