8 BULLETIN 314, U. S. DEPARTMENT. OF AGRICULTURE. 
closed by the cover b. To the conical bottom of a is fitted a conical 
outflow tube c, exactly 20 millimeters long, with a diameter at the 
top of 2.9 millimeters and at the bottom of 2.8 millimeters. This 
tube can be closed and opened by the pointed hardwood stopper d. 
Pointed metal projections are placed on the inside of a at equal dis- 
tances from the bottom and serve for measuring the charge of mate- 
rial, which is 240 cubic centimeters. The thermometer e is used to 
ascertain the temperature of the material to be tested. The vessel 
ais surrounded by a brass jacket f, which holds the material used as 
a heating bath. either water or cottonseed oil, according to the tem- 
perature at which 
the test is to be 
made. <A tripod g 
serves aS a support 
for the apparatus 
and also carries a 
ring burner A by 
means of which the 
bath is directly 
SS a = heated. The meas- 
|__ ©! ee Heh uring cylinder of 100 
| 
| cubic centimeters 
| capacity, which — is 
sufficiently accurate 
for work with road 
materials, is placed 
directly under the 
outflow tube. 
iat 
TNR 
Jj = As all viscosity de- 
ee terminations should 
Fic. 4.—Hngler viscosimeter. 3 
be compared with 
that of water at 25° C., the apparatus should be previously calibrated as 
follows: The cup and outlet tube should first be scrupulously cleaned. 
A piece of soft tissue paper is convenient for cleaning the latter. The 
stopper is then mserted in the tube and the cup filled with water at 
25° ©. to the top of the projections. The measurimg cylinder should 
be placed directly under the outflow tube so that the material, upon 
flowing out, will not touch the sides, and the stopper may then be — 
removed. The time required both for 50 and 100 cubic centimeters 
to run out should be ascertamed by means of a stop watch and the 
results so obtained should be checked a number of times. The time 
required for 50 cubic centimeters of water should be about 11 seconds 
and for 100 cubic centimeters about 22.8 seconds. 
Bituminous road materials are tested m the same manner as water 
and the temperature at which the test is made is controlled by the 
bath. The material should be brought to the desired temperature 
