ANALYTICAL CHEMISTRY
1508
Table I\’.
Reproducibility of Flow Times €or Typical Oil, B
-FlowViscometer Oil R ,100° F.
Average value Viscosity, cs.
D
time. seconds
% deviation
685 74 685 65 685 7 5 685 64 685 31 685.66
0 01 0 00
from mean
0 01 0 00 0 01
66 6 9 1
Viscometer E _____ Flow time, % deviation seconds from mean 222 08 0 00 222 19 0 0; 222 10 0 01 221 9G 0 03 222 05 0 01 222.08
Oil C . 100’ F.
.4\ erage value T‘i,cosity,
CS.
from mean
0.03 0 Oi 0.03 0 03 0 03
B
100.F
0.1 02
oa
-.
% deviation
c w L
66,695
Table I-. Reproducibility of Flow Times for Typical Oil, C Viscometer EViscometer F Flow time, seconds 1216.4 1216.8 1215.6 1215.6 1215.6 1216 0 365.19
110
Flow time, seconds 372 19 372 08 371 84 371 89
371.90 371 98 3 6 5 26
yo deviation
---e I
1
I
Figure 3.
.
?
3
3 6 TIME IN MINUTES 4
7
8
9
10
Time to Attain Temperature Equilibrium
from mean
0.00 0 03 0 04 0.02 0.02
baths and a lowtemperature bath. The constructional details of the auliliary equipment with vhich this viscometer is u-ed and typical data a t temperatures as low as - 100’ F. and as high as 700” F. F\ ill be presented in a later paper. LITERhTURE CITED
a frequency of 1 cycle per 40 seconds. This cyclical nature reduced the error introduced by the temperature fluctuations. It can be Been t,hat the reproducibility is \Tell within the i O . l % of the average value as required by the ASTLI tentative method of test for kinetic viscosity (1). Viscometers A and B were calihrated independent,ly with water, and the viscosities obtained on the same oil are in good agreement. Oils B and C show that t’ie step-up procedure of calibration does not introduce significant errors in the calibration constant, since the difference in viscosities of oil C measured in viscometers E and F is less than 0.027,. Tables I11 to V indicate that adequate calibration can be achieved without the use of master viscometers. I n the cooperative tests conducted by the ASTAl in 1950, reeults obtained using the Zeitfuchs cross-arm type viscometer compared well with the average values obtained from several types of capillary viscometers. The accuracy of the cross-arm viscometer is as good as other capillary vi,xometers. A considerable temperature range can be covered .u-ith thc cross-arm type viscometer by use of ausiliary saturated vapor
(1) Am. Soc. Testing hfaterials, “ S t a n d a r d s on Petroleum P r o d u c t s and Lubricants,” ASTBI Designation D 448-46T,19.50. (2) Barr, G., “A BIonograph of Viscometry.” p. 127, London, Oxford University Press, 1931. J. D.. “Variation of t h e Kinetic Energy Correction with Reynolds Xumber,” thesis, Pennsylvania S t a t e College, 1947. (4) Bingham, E. C., and Thompson, R. R., J . Rheol., 1, 418 (1930). ( 5 ) Bingham. E. C., a n d Young, H. L., J . Ind. Eng. Chem., 14, 1130 (1922). ( 0 ) Cannon, AI. R., ISD.ENG.THEM., ASAL.E D . , 1 6 , 7 0 8 (1944). (7) C a n n o n , A f . R..slid Fenske, 11.R., Ibid., 10, 297 (1938). (8) Ibid., 13, 299 (1941). ( 9 ) Cannon, AI. R., and Fenske, 11.R., Oil Gas J., 3 3 , 5 2 (1935). (IO) FitzSimons, I K D . E B G . CHEJI., .kS.xL. ED., 7,345 (1935). i l l ) Jones, G., and Ferrell, E. J.,C k e m . S U CLondon, . 1939,325. (12) Ruh, E. L., Valker, R. W., and D e a n , E. IT.,IND. ENG.CHEX., ANAL.ED.,1 3 , 3 4 6 (1941). (13) 8n-indelle, J. F . , J . Colloid Sci., 2, 177 (1947). (14) I-bbelohde, L., IXD.ESG. CHELI..ANAI..ED..9 , S5 (1937). (1.5) Zeitfuchs. E. H., Oil Gas J . , 44, S o . 36, 99 ( J a n . 12, 1946). (16) Zeitfuchs, E. H., P i o r . A m . Petroleum Insf.,20 (III),104 (1939). (17) Zeitfuchs, E. H., a n d Lantz, T-., private communication.
( 3 ) Bell,
o.,
R E C E I V Efor D reiiew February 16, 1952. Accepted June 12. 1952.
Determination of Kerosene in Kerosene-Gasoline Mixtures JOHN E. BRIDGES Western Counties Laboratories, Bristol, England
T I S common practice t o examine mixtures of kerosene and
I gasoline, for control purposes, by methods based on distillation, specific gravity, or refractire index. The following is suggested as an alternative method. For a batch of samples, i t is quicker than distillation. X standard distillation takes about 2.5 minutes. I n the following method, the prdiminary standardization can be done in about this time, and subsequent titrations a t about 5 minutes each. Another advantage is the increased sensitivity for small concentrations of gasoline, for the “tops” of gasoline and the “bottoms” of kerosene overlap in most instances. The method is empirical, and can be uscd only for checking blends of kno-ivn constituents. METHOD
The reagent is a 0.1% solution of amaranth in approximately 95% ethanol. (Amaranth is used t o facilitate the detection of tn.0 phase$.) Five milliliters of the sample are pipetted into a 100-ml.
stoppered cylinder and the ethanol reagent is added in 0.25-ml. portions from a buret. The whole is shaken vigorously after each addition and the tube is then held up to the light for examination. At first the emulsion will rapidly separate into tu-o layers, but as the miscibility point is approached this separation decreases, though the contents remain distinctly cloudy. T h e true end point may be clearly seen when the addition of 0.25 ml. causes the solution to change from cloudy to clear. This is the miscibility point. Experiments shovi that the miscibility point depends on four variables (see Tables I to 111). 1. The kerosene-gasoline ratio 2. The alcohol-mater ratio, in the alcohol used 3. The temperature 4. The types of kerosene and gasoline being examined Consequently it is essential t o standardize factors 2, 3, and 4. Factors 2 and 4 are readily kept constant by standardizing the alcohol reagent against knov-n mixtures of the actual gasoline and kerosene knon-n t o be present in the mixture. The method is not applicable to mixtures of unknon-n origin.
V O L U M E 2 4 , NO. 9, S E P T E M B E R 1 9 5 2 Table I.
1509
Effect of Kerosene Content on the Alcohol Required for Dissolution
Tziiip..
C.
20
Alcohol used, 93.4% by volume a t 15.5' C. Gasoline used, British pool spirit Alcohol Required for Kerosene Gasoline hIiscibility Point, 111. 70 by volume Si1 100 19.5 80 20 i "37.5 'O 50 50 12.0 21.5 142.0
12
Table 11. Effect of Strength of Alcohol Used on Data Shown in Table I
Iiil 20 50
Alcohol used, 9.7.3L;: by volume a t 13.3° C. Gasoline used, British pool spirit Alcohol Reqiiired for Kerosene Gasoline BIiscibility Point, AII. % by volume 14.5 h-il 100 20 80 23.5 46.5 50 50
TEinp..
C.
20
100 80
[E 54.5
12
50
Table 111. The temperature effect has been investigated over the range 12' to 20" C., and the follon-ing facts emerge (Table 111). For niistures containing up t o 2OY0kerosene, a temperature difference lietween standardization and determination. of 1 C., will amount to only about 0.25% on the apparent kerosene content (1.25% error). For mixtures richer in kerosene, this variable becomes inereasingly critical, until a t 50% kerosene a departure from the standardization temperature of 1 " C. is equivalent t o an error of 0.75% on the apparent kerosene content (1.50% error). If the laboratory temperature is fairly constant, this temperature effect can he ignored, but if great precision is required, this
50
20
50
100 80
50
Temperature Effect Expressed as a filean Coefficient, from 12" to 20" C.
Kerosene in Mixture, Yo h'll 20
Xi1
93.4% Alcohol, 111. per 1' Rise 0.125 0 . 2.50 0.56:3
92.3% Alcoho1,'MI. per 1' Rise 0.188 0.313 1.000
variable may be eliminated by standardizing the alcohol inimediately before the set of determinations. The relevant results are set out in Tables I to 111. R E C E I V Efor D review October 24, 1951. Accepted June 5 , 1952.
Equilibrium Constants in the Interaction of Carbonyl Compounds with Hydroxylamine NATII.AN SHAROS, Tlie .4gricuZturaZResearch Station AND
AH.IROS KATCHALSKY, The W'eitrnann Institute of Science, Rehocot, Israel
HE decrease in p H accompanying the rezction of amino acids rand of aldehydes is used extensively for the analytical determination of amino acids and peptides. Levy ( 2 ) evaluated, from the p I I depression, the equllibrlum constants of the formol interaction. Equilibrium constants of the interaction of aldoses with amino acids and peptides &-ere determined in a similar manner b y Ilatchalsky (1). Recently, Roe and 3IitcheIl (3) proposed the use of the p H drop, folloii-ing the mixing of hydroxylamine hydrochloride n ith carbonyl compounds, as a rapid means for the quantitative analysis of aldehydes and ketones. The data given by Roe and hfitchell comply satisfactorily 'i\ ith the theory proposed for the interaction of aldose- and amino acids and may be used for the evaluation of suitable equilibrium constants. The proposed mechanism of the interaction is: K
HOSHs+ &H O S H L +A
30
20 I
n Q
cn
.0
&
c
10
+H+ 0
where A is the carbonyl compound.
10 20 Conc. of butyraldehyde x103
D
Figure 1. Determination of Equilibrium Constant L f o r Interaction of Butyraldehyde and Hydroxylamine
Hydrochloride In aqueous solution, Equation 12
Let us denote the total concentration of the carbonyl compound by 0 and the total concentration of hydroxylamine by CB. Denoting the initial concentrations by a subscript o we get
+ A:KOH + (+",OH), SHzOH + 'Tu"30H + A:NOH
CA = A, = A CB = (",OH),
(3)
=
(4) hIaking use of Equation 3 and the equilibrium Equation 2 we find
A :SOH =
L.CA.KH,OH 1 L.
+ h"m
The concentration of S H L O Hat the pII a t the end of the euperiment (about pH 2.5) is sufficiently small to make L.SHLOH< 1. Therefore, A : S O H = L.CA.SH,OII
