56 
CHEMISTRY: RICHARDS AND DAVIS 
Toluene was prepared from commercial pure toluene by shaking with 
successive portions of sulphuric acid until the acid remains colorless. 
Further agitation with mercury until it had ceased to pollute a clean 
mercury surface, washing with water, and many times repeated dis- 
tillation followed. The fraction which came over in the immediate 
neighborhood of 110.31° under normal pressure was retained as pure.* 
Several samples from different sources were employed. 
There follows the record of the last three (and most successful) de- 
terminations of the heat of combustion of napthalene, chosen as a 
standard substance, and of three determinations of the heat of combus- 
tion of toluene, conducted in the thin sealed bulb with a rim of paraffin 
around the top of the containing crucible, as already described. Since 
they were thus all made over about the same range of temperature 
any uncertainty in the calibration of the thermometer largely disappears 
from the result — nevertheless this was carefully calibrated. These 
determinations serve to indicate the consistency attainable by use of 
the precautions just described. 
Napthalene 
NO. OF 
EXP. 
WEIGHT 
NAPTHALENE 
WEIGHT OF 
COTTON FOR 
IGNITION 
SUM OF ALL 
CORREmONS 
t\ 
/: 
CORR. RISE OF 
TEMPERATURE 
degrees 
degrees 
degrees 
degrees 
5 
1.1537 
0.008 
0.0220 
16.008 
20.202 
3.616 
6 
1 . 1002 
0.0095 
0.0260 
16.036 
20.043 
3.618 
7 
1.1023 
0.008 
0.0222 
16.046 
20.059 
3.615 
3.616 
Toluene. 
NO. OF 
EXP. 
WEIGHT 
TOLUENE 
IGNITION MATERIAL 
CORRECTION 
CO 
FOUND 
CORR . RISE 
OF TEMPER- 
ATURE FOR 
1 GRAM. 
degrees 
degrees 
degrees 
degrees 
6 
0.9154 
Paraffin 
0.4256 
None 
15.961 
19.885 
3.822 
0.0982 
Cotton 
0.0036 
7 
0.9986 
Paraffin 
0.4143 
2.0cc. 
15.553 
19.782 
3.820 
0.0953 
Cotton 
0.003 
8 
1.0566 
Paraffin 
0.3348 
1.7cc. 
15.987 
20.357 
3.822 
0.0747 
Cotton 
0.0079 
3.821 
