92 TRANSACTIONS OF THE 
force some of the gases containing hydrogen and carbon 
back into the air purifer. 
The nitrogen was determined by the ordinary ‘“Kjel- 
dahl” method, distilling the ammonia into standard sul- 
phuric acid and titrating back the excess. 
The sulphur was determined by the Sprague-Ebaugh 
modification of the Eschka method which consists in baking 
a weighed sample with zinc oxide and sodium carbonate. 
The sulphur is oxidized to the sulphate and leached out with 
water, filtered, acidulated with hydrochloric acid and pre- 
cipitated and weighed as barium sulphate. 
The ash may be determined by reweighing the boat 
after combustion or by heating a one gram sample in a 
platinum dish till all carbon is burned off, and then re- 
weighing. In two cases the ash was analyzed. The com- 
positions are given in a separate table below Table 2. This 
analysis shows the mineral matter of rock asphalt to be of 
silicious nature. 
Table 3 records the results of a series of solubility 
tests. These results give the amount of hydrocarbon that 
can be dissolved by 100 grams of the solvent. The method 
was as follows:—a quantity of hydrocarbon was placed in 
a bottle in contact with a small amount of solvent. The 
bottle and contents were agitated for 18 hours by a water 
motor and shaking apparatus, and then the solution was 
filtered off. A weighed quantity of the solution was 
evaporated and the residue weighed and calculated to 100 
grams of solvent. All of the solvents tested were first 
tried qualitatively hot and cold, and where solubility was 
found a quantitative determination was made. Quantitative 
determinations with hot solvents were made only where in- 
creased solubility was found in the qualitative test. The 
hot extractions were made in a bottle fitted with a reflux 
condenser, the solvent being boiling. The hot extractions 
are starred in Table 3. 
Table 4 gives the results of fractional distillations of 
the hydrocarbons. A ten gram sample was placed in a 
glass distilling flask and heated until some material came 
over. Fractions were taken according to the table given. 
