52 BULLETIN 949, U. S. DEPARTMENT OF AGRICULTURE. 
The sensitiveness of the thermometer shall be such that when cooled to a tempera- 
ture of 74° C. below the boiling point of water at the barometric pressure, at the time 
of test, and plunged into free flow of steam, the meniscus shall pass the point 10° C. 
below the boiling point of water in not more than 6 seconds. 
The thermometer shall be set up as for the distillation test, using water, naphthalene 
and benzophenone as distilling liquids. The correctness of the thermometer shall 
be checked at 0° and 100° C. after each third distillation until seasoned. 
(c) Condenser. — The condenser tube shall have the following dimensions: 
Mm. 
Adapter 70 
Length of straight tube 185 
Width of tube 12 to 15 
Width of adapter end of tube 20 to 25 
(d) Stands. — Two iron stands shall be provided, one with a universal clamp for 
holding the condenser, and one with a light grip arm with a cork-lined clamp for hold- 
ing the flask. 
(e) Burner and shield. — A Bunsen burner shall be provided, with a tin shield 20 cm. 
long by 9 cm. in diameter. The shield shall have a small hole for observing the flame. 
(/) Cylinders.- — The cylinders used in collecting the distillate shall have a capacity 
of 25 c. c.j and shall be graduated in 0.1 c. c. 
(4) The apparatus shall be set up as shown in figure 28, the thermometer being 
placed so that the top of the bulb is opposite the middle of the tubulature. All con- 
nections should be tight. 
(5) One hundred cubic centimeters of the dehydrated material to be tested shall 
be placed in a tared flask and weighed. After adjusting the thermometer, shield, 
condenser, etc., the distillation is commenced, the rate being so regulated that 1 c. c. 
passes over every minute. The receiver is changed as the mercury column just 
passes the fractionating point. 
The following fractions should be reported : 
Start of distillation to 110° C. 
110 to 170° C. 
170 to 235° C. 
235 to 270° C. 
270 to 300° C. 
Residue. 
To determine the amount of residue, the flask is weighed again when distillation 
is complete. During the distillation the condenser tube shall be warmed when nec- 
essary to prevent the deposition of any sublimate. The percentages of fractions 
should be reported both by weight and by volume. 
32. STANDARD METHOD FOR DETERMINATION OF SOFTENING POINT 
OF BITUMINOUS MATERIALS OTHER THAN TAR PRODUCTS (RING- 
AND-BALL METHOD). 
(A. S. T. M. Standard Method, Serial Designation, D 36-19.) 
Note. — It was recommended by the conference that this method be followed 
for both asphaltic and tar products 
(1) The softening of bituminous materials generally takes place at no definite mo- 
ment or temperature. As the temperature rises, they gradually and imperceptibly 
change from a brittle or exceedingly thick and slow flowing material to a softer and 
less viscous liquid. For this reason, the determination of the softening point must 
