V O L U M E 21, NO. 4, A P R I L 1 9 4 9 Table I.
507
Comparison of 3- or 5-111. Pycnometers with 25311. Specific Gravity Bottle Viscosity, Cs. a t 200 c. 3.7
Light oil Uediuni oil Viscous oil Vi-cous black oil
d;oq
0.8390
,520
0.9311
i2no
0.9433
216.50
0.9647
104 X Deyiation of Indiyiduai Determination Cup type Side-arm typr 1 2 1 2 -3 ,.. +1 -1 0 ... +1 ... +1 ... 0 ... -1 -3 -1 0 t l -3 0 0 t i 0 0 0 +1 -2 +1 -1 0 -1 0 +I -8 t l (1 0 0 -2 -1
1-aplithenir aril1
2300
0,9749
0 +1
0
... ... -1
-1
-2
-2
-t
-2
1
1
0 1
Table 11. .Accuracy of 3- or T,-ml. Pycnometers
..
. . . . . . . . . . . .
. . . . . .
.Ir. del-iation
...
nierits showed that 10-nil. pycnonieters were no mole accuratr and that 1-nil. pycnometers gave densities accurate withill + 0.0006. Speed. Each determination requires 15 to 30 minutes of thr operator's time, depending on the viscosity of the sample. The elapsed time is somewhat longer, eqpecially when thf, siphonmy technique i i u-ed for filling.
...
Light oil AIediuiii oil
Viscosity, Cs. a t 200 c. 24
0.8992
420
0,4298
dio'L
104 X Deriation of Indiyidual Determin&Kii Side-arm c u p type type -1 -3 -2 -3
from the rack and placed in the therniostated bath. The liquid level is maintained between 6.0 and 6.4 in the long a r m by attaching a rubber tube and applying suction.
Accuracy. Table I shows a coniparison of densities deteriiiined in the 3- or 5-mI. sizesof the two typesoi'p?'cilometer by twi operators and in n 25-nil. specific gravity bottle for oils ranging from 4 t o 22,000 cs. a t 20" C. The agreenieiit among the three instruments is good and the precision from both the cup type and side-arm type is *0.0001 to 0.0002 gram per nil. Table I1 s h o w that the accuracy of individual measureiiieiita in the two types is also of the order of +0.0002. T h e densities of the oils used to determine accuracy were determined xithin *0.0001 on 100-nil. samples by the Sational Bureau of Standards. Several pycnometers of the cup type and side-arm type were used for the measurements shown in Tables I and 11. The two types of pycnometer give equally accurate results. It is reconimcnded t h a t a 3- or 5-nil. pycnometer he used for routine dettmi~in:~tionaccurate within *0.0002 gr~iiiipt.r ml. l
