Determination of Alkali Metals in Silicates and ... - ACS Publications

concentration of alkali metal in the sodium and potassium chloride solutions was checked byevaporating 10.0 ml. of each solution in a platinum dish wi...
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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