308 University Geologicai Survey of Kansas. 
products, appointed at the third International Petroleum Con- 
gress at Bucarest, is now at work. Since the oils found in 
different fields differ in many respects it is necessary to adapt 
the method to local needs. 
PRELIMINARY EXAMINATIONS. 
Upon undertaking the examination of Kansas crude oils it 
was therefore thought advisable to make preliminary distilla- | 
tions in order to determine the temperature at which ‘“crack- 
ing” or decomposition begins, and also to find out how to pro- 
ceed in order to prevent cracking as far as possible. 
Two samples of crude oil, No. 3, from Urbana, and No. 4, 
from Humboldt, were distilled under ordinary atmospheric 
pressure, from a half-liter distilling flask which was provided 
with two thermometers, one showing the temperature of the 
oil in the flask, the other the temperature of the vapors. The 
results are plotted in curves in the lower right-hand portion 
of plate XLI. 
Small circles upon the curves mark the progress of the dis- 
tillation. The horizontal distance to any given circle, measured 
from left to right, indicates the total percentage, by weight, of 
oil collected up to the time the observation was made. The 
vertical height of the same circle indicates the specific gravity, 
or density, of the portion collected at that time. The number 
of degrees noted adjacent to the circle shows the temperature, 
Centigrade, reached by the vapors when the portion was re- 
‘moved. 
It will be seen that nearly 10 per cent. of gasoline having a 
specific gravity of about 0.75 was collected below 150° C. 
During the distillation of the kerosene, which includes all that 
portion of the oil which passes over from 150° to 300° C., the 
rise in temperature and increase in specific gravity is propor- 
tionate to the percentage of oil distilled. Beyond this point, 
however, the specific gravity of the distillate reaches a maxi- 
mum of about 0.84 when about half the oil is distilled, after 
which the gravity decreases until more than 80 per cent. has 
been distilled. This is due to the fact that certain constituents 
of the oil are decomposed by the heat into simpler or lighter 
products, some of which are gaseous but most of which are 
liquids, and a small portion consisting of solid charcoal or 
coke. This process is technically known as “cracking,” and 
many attempts have been made to employ the cracking process 
