EXAMINATION OF BITUMINOUS ROAD MATERIALS. 7 
testing flame. The testing flame is obtained from a jet of gas 
passed through the piece of glass tubing and should be about 5 milh- 
meters in length. 
The flash test is made as follows: The oil cup should first be 
removed and the bath filled with cottonseed oil. The oil cup should 
be replaced and filled with the material to be tested to within 3 
millimeters of the flange joining the 
eup and the vapor chamber above. 
The glass cover is then placed on the oil 
cup and the thermometer so adjusted 
that its bulb is just covered by the bi- 
tuminous material. The Bunsen fiame 
should be applied in such a manner that 
the temperature of the material in the 
cup is raised at the rate of about 5° 
C. per minute. From time to time 
the testing flame is inserted in the 
opening in the cover to about half 
way between the surface of the ma- 
terial and the cover. The appearance 
of a faint bluish flame over the entire 
surface of the bitumen shows that the 
flash point has been reached and the 
temperature at this point is taken. 
The burning point of the material 
may now be obtained by removing the 
elass cover and replacing the thermom- 
eter in a wire frame. The tempera- 
ture is raised at the same rate and the 
material tested as before. The tem- 
perature at which the material ignites 
and burns is taken as the burning point. 
At the conclusion of this test the ie. 9—New York State Board 0’ Health 
flame should not be blown out for dan- Geese 
ger of splashing the hot material. A metal cover or extinguisher should 
be employed for this purpose by placing it over the ignited material. 
OPEN-CUP METHOD. 
A number of open-cup oil testers have been devised which are 
similar in design and give practically equivalent results. This type 
is shown in figure 10. It consists of a brass oil cup a of about 100 
cubic centimeters capacity. The outer vessel 6 serves as an air 
jacket. No glass cover is used in the open-cup method. A suitable 
8016°—Bull. 314—15 3 
