74 
BULLETIN 1216, U. S. DEPARTMENT OF AGRICULTURE. 
requires To he brought to a higher temperature than 38° C. in 
order to render it completely fluid, it shall he tested at the 
lowest temperature at which it is completely fluid and a cor- 
rection made by adding 0.0008 to the observed specific gravity 
for each degree centigrade above 38° C. at which tbe test is 
made. This correction factor does not apply with equal accu- 
racy to all oils, but serious error due to its use will be avoided 
if the foregoing precaution is observed with respect to avoiding 
unnecessarily high temperature. Before taking the specific 
gravity the oil in the cylinder should be stirred thoroughly with 
a glass rod, and this rod when withdrawn from the liquid should 
show no solid particles at the instant of withdrawal. Care 
should be taken that the hydrometer does not touch the sides 
or bottom of the cylinder when the reading is taken and that 
the oil surface is free from froth and bubbles. 
Distillation. 
Distillation 9. (a) Retort. — This shall be a tubulated glass retort of the 
retort form and approximate dimensions shown in Figure 10 with a 
capacity of 250 to 290 cubic centimeters. The capacity shall be 
measured by placing the retort with tbe bottom of tbe bulb 
and tbe end of tbe offtake in the same horizontal plane, and 
pouring water into the bulb through the tubulature until it 
overflows the offtake. The amount remaining in the bulb shall 
be considered its capacity. 
..>'Approx.lt9cm. 
■Approx. 2, 85 an. 
Jpprv/. 
t.ZScm. 
Capacity of Bulb 
2S0fo290cc. 
Fig. 10. — Retort for distillation test. 
Condenser (b) Condenser tube. — The condenser tube shall be a suitable 
tube. form of tapered glass tubing of the following dimensions: 
Diameter of small end: 12.5 millimeters; permissible vari- 
ation, 1.5 millimeters. 
Diameter of large end: 28.5 millimeters: permissible vari- 
ation 3.0 millimeters. 
Length: 360.0 millimeters: permissible variation, 4.0 milli- 
meters. 
Shield. ( f ') Shield. — An asbestos shield of the form and approximate 
dimensions shown in Figure 11 shall be used to protect the re- 
tort from air currents and to prevent radiation. This may be 
covered with galvanized iron, as such an arrangement is more 
convenient and more durable. 
Receivers. (d) Receivers. — Erlenmeyer flasks of 50 to 100 cubic centi- 
meter capacity are the most convenient form. 
Thermometer. (e) Thermometer. — The thermometer shall conform to the fol- 
lowing requirements: 
The thermometer shall be made of thermometric glass of a 
quality equivalent to suitable grades of Jena or Corning make. 
It shall be thoroughly annealed. It shall be filled above the 
mercury with inert gas which will not act chemically on or 
