V O L U M E 20, NO. 7, J U L Y 1 9 4 8
681
Table 1. Titration oC Sodium Carbonate Solutions* Volume of &SO. A".
Na?COa
N~~CO* Taken M1. 10.00 25.00 4n.00
moo
L"
mu-
tion Gram o.1060
n.z6&n
0.2
N M1. in.02
25.03
n.4240 40.00 0 . 2 6 ~ 0 ... 0,6625
...
deviation from mean
M1. 0.01
0.02
Used A". &vistion 0.6 froln mean A'
1x1. ...
iM1.
1O:Oo 26.08
n:Oi
...
0.02
.. ..
.. ..
0.02 40.00 1.06oo .,. ., 40.05 0.03 All v&lues represent average 01 five deterrninationi. 25.00
rhcoJ Found
Gram 0.1062 0.2653 0.4240 0.2650 0.6632 i.0612
~ ~ lion
% fO.lQ +0.11 0 0
+O.I~ +O.II
red The first transition occu~sat a pH of 4,0 with the appearance of a faint color. At a p~ of 3 4 an emphatic and sharp change to purple takes place. This was the end point to which %lltitrations were conducted, The final conversion to n bluish purple takes place new a pH of 3.0.
I n the electrometric standardization of the sulfuric acid six determinations were made on esch solution. Results of determinations on the 0.2 N acid showed au average deviation from the mean of 0.03%; those of determinations on the 0.5 N acid showed an average deviation from the mean of 0.0140/0. The indicator titrations were conducted in Erlenmeyer flasks i resting a on a white background. Five determinations were made on each of 10.00-, 25.00-, and 40.00-ml. volumes of the sodium carbonate solutions. One drop of 0.1% indicator was used for each 10 ml. of solution a t the end point. Titrations were conducted to the first definite purple color. No eolar standard was used; the color response is so good as to render such a standard superfluous, and artificial light or daylight can be used with equal &. *.r t i" r. i. o" n ~" ." ~". I..
Results given in Table I indicate the precision and accuracy obtainable when the new indicator is used. Comparable results were obtained i n 6 series of determinations in whioh samples of solid carbonate were titrated directly. One may conclude that the new indicator is satisfactory for ordinary titrations of sodium cmbonate with sulfuric acid. LITERATURE CITED
EXPERIMENTAL DETAILS
I n the experimental work standmd 0.2 N and 0.5 N solutions of sodium carbonate were prepared by dissolving the reagent grade salt in carbon dioxide-free distilled water. Sulfuric acid solutions
honate solutions, with the experimental indicator. Experimental conditions were equalized as far as possible by employing the same burets for the electrometric and the indicator titrations.
(1922). (3) MoIlvaine, T.C.,J . B i d . Chem.,49.183-6(1921). (4) Sehulte, Gustav. "Farbstofftabellen," p. 293, Berlin, Weidmernnsche Buchhandlung. 1929. ( 5 ) Taras, M., ANAL.Cniu., 19,339-41 (1947). (6)Willard. H.H., and Furman. N. H., "Elementary Quantitstive Analysis," p. 115, New York. D. Van Nostrand Co.. 1935. R ~ c m v mJune 13, 1947
Kinematic Viscometer Tube Cleaning Apparatus JAMES MCGLYNN, Socony-Vacuum Laboratories, Technical Seruiee Department, Brooklyn, N . Y . ANY petroleum laboratories, where large numbers of kinematic viscosity determinations are made, are confronted with the problem of cleaning the modified Fenske-Oswald kinematic viscometer tubes. This operation normally, in addition to being time-consuming, requires large volumes of solvent, necessitates a large stock of tubes, and is accompmied by high breakage. This paper describes an apparatus by means of which a number of tubes may he attached to a manifold and solvent circulated through them until the mineral oil has been thoroughly flushed out. From one to eight viscometer tubes can he cleaned in
approximately 5 minutes. I n the author's laboratory this allows twice as many tubes to be washed in unit time. The use of this equipment results in a reduced consumption of solvent for cleaning and cuts down the amount of tube breakage by reducing the required handling. A somewhat similar apparatus has previously been affersd for sale by laboratory supply houses, includiag C. J. Taglisbue Company, Park & Nostrand Aves., Brooklyn, N. Y. The apparatus described in this article may he purchased from the Emil Greiner Co., 1151Sixth Ave., New York, N. Y. APPARATUS
The kinematic viscometer tube cleming apparatus (shown in Figure 1) consists of the following park: Solvent reservoir construeted of sheet brass having a capacity of approximately 3 gallons. G.E. explosionproof motor, 1\20 h.p., 110-volt, 60cycle, I-phase, G.E. catalog No. 5 KH 23 AC 15. Centrifugal pump, capacity 3 gallons per minute, M. L. Oberdorfer Brass Company, Syraeusc, N. Y. Valve manifold far connecting the modified Fenske-Ostwald kinematic viscometer tubes to the system. Pressure relief valve set a t 1pound pressure per square inch. Line filter, Located on the discharge side of the pump. Rack for supporting the viscometer tubes in an inverted position. An amembly drawing of the equipment is shown in Figure 2 (key cocks &s indicated on this drawing are to he preferred to the needle valves shown in Figure 1). PROCEDURE
Figure 1. Kinematic Visoometer Tube Cleaning Apparatus
The solvent reservoir is charged with a light petroleum solvent. The usual precautions relative to the use of inflammable solvents should he observed. The viscometer tubes, drained of excess oil, are connected to the valve manifold in inverted positions. The large-diameter side arm of the viscometer is connected to the manifold by means of a 2-inch length of thick-walled synthetic rubber tubing, 0.375 inch in inside diameter. The smdlll-diameter side arm of the tube is placed in the opening in the topof the reservoir and supported in the rack provided. The valves are opened
682
ANALYTICAL CHEMISTRY
and the solvent is forced into the large side arm of the tube, discharging through the small side arm into the reservoir. The circulation is continued until the tubes are washed free of oil. The valves are closed, and the tubes are removed from the apparatus, rinsed with acetone, and dried by drawing air through them. The entire Cleaning operation for eight viscometers requires approximately 5 minutes. When the oil concentration in the solvent is such that the vi>cometers are not thoroughly cleaned, the solvent is pumped of the reservoir by attaching a length of synthetic rubber tuhirig to one of the valve outlets and is discharged to a suitable container for disposal. Three gallons of solvent will clean approximatelv three hundred tubes.
4 ' \
I
,
I
b
d
I
, Figure 2.
3.
4. 5. 6. 7. 8.
9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20.
RECEITED 4ugUst 11, 1947.
1,
\
1.
Of additives. Except for cases as mentioned below, no condition has been encountered where a light petroleum solvent will not satisfactorily clean the tubes iyhen the procedure as outlined is followed. Viscometer tubes soiled with used oils, asphaltic materials, or way products are rinsed with a suitable solvent before being mounted on the apparatuq, in order to avoid exceSaive contamination of the solvent in the reservoir,
.
21
2.
The author's laboratory has had occasion to test large numbers of competitive,used, and compounded oils containing many types
1,s inch copper tubing, coiiimrrcial T w o l/z inch coupling nuts, cominerciul ' T n o connector couplings. commercial Wood pump base Oberdorfer centrifugal pump 311 X 5/16 inch flexible coupling, coiiiriiarcial G.E. explosionproof motor, 1 '10 h.p.. 172.5 v . p . i n . . 1I , i - w l r , alternating current Wood mounting base Brass mounting plate 4 brass tank supports Brass compression elbow 12 brass No. 5-40 flat-head machine screwy 1-lb. check valve 9 brass tees, I / P X l / r X ' ~ r i n c h I / r inch brass pipe plug s;3 inch copper tubing 4 coupling nuts 3 connector couplings 11, inch brass elbow Brass tank, 9 X 2 4 X 6 inches ( S o . 14 gage)
Diagram of .ipparatiis 21. Brass tube strap bar 22. Brass tank cover 23. 31s inch brass pipe plug 24. 16 brass S o . 4 flat-head wood screws 25. 31 brass KO.5-40 round-head machine screws 26. 8 commercial KO.4-40 flat-head machine s c r e w 27. 8 steel spring clips 28 8 rubber hose 29. Copper catch tray 30. 8 brass nipples 31. 8 brass ground key cocks (Lunkenheimer), '1, inch 32. 8 brass nipples, 1/4 inch 33. 3 brass nipple straps 34. 2 brass street elbows 35. Oil filter 36. 6 brass KO,12 round-head wood bcrews 37. 8 brass KO.5 round-head vood s c r e w 38. Brass draincock 39. 2 brass tube strap bar supports 40. 2 brass 11, inch 20-thread round-head machine screws
