NOVEMBER 15, 1935
ANALYTICAL EDITION
TABLEVII.
SOLVENT POWER OF PUREHYDROCARBONS OBTAINEDWITH VARIOUS STANDARD KAURIBUTANOL SOLUTIONS
Hydrocarbons
Solution A From Figure
Calculated
Benzene .~~_.~~. 100.0 Toluene Ethylbenzene Deoahydronaphthalene Methylcyclohexane n-Heptane
94.8 85.1 60.6 51.0 25.4
2 100.0 94.8 85.1 60.6 51.0 25.4
Solution B From Figure
Calculated 100.0 92.4 84.9 58.3 48.3 23.3
2 100 92.8 85.5 59.7 49.8 26.4 IO
TABLE VIII. SOLVENT P O W E R O F 'n-HEPTANE-BENZENE BLENDS (BY VOLUME) Solution A Kauri butanol Solvent value power
Blend %-Heptane Benzene
% 0 20 40 60 80 100
Solution C From Figure
Calculated 100.0 93.3 84.7 58.6 48.1 23.1
103.0 87.5 68.0 49.7 36.0 26.2
100.0 85.0 66.0 48.2 35.0 25.4
Solution B Kauri butanol Solvent value power 113.0 95.6 73.3 51.8 37.1 26.3
From
Figure
2 100.0 94.0 85.8 60.5 49.9 25.4
100.0 93.9 87.0 59.5 48.7 23.7
Solution E From Calcu- Figure lated 2 100.0 93.1 84.7 60.7 48.2 23.4
100.0 93.5 86.1 61.7 49.8 25.4
Blends n-Heptane
Solvesso No. 2
%
%
Kauri Butanol Value
Solvent Power
Solvesso No. 4 Benzene equivalent of standard solution, 113.8 cc. 0 100 No end point 90.36
10 40 70 100 a
90 60 30 0
92.9 64.7 42.1 26.3
Obtained by direct determination.
Inasmuch as the pure paraffin hydrocarbons have the lowest solvent powers as measured by aniline, kauri butanol value, or dimethyl sulfate value, it is very unlikely that commercial solvents will have solvent powers lower than that of n-heptane. For this reason the position of the curve lower than 25.4 per cent solvent power has not as yet been investigated by the authors. Literature Cited C.;Shipp, V. L., and Spelshouse, W. E., ISD.EXG. CHEW,Anal. Ed., 5, 307 (1933).
(1) Beard, L.
(2) International Critical Tables, Vol. 1, p. 215 ( 1 9 2 6 ) . (3) Kiehl, J. R., Am. Paint Varnish Mfm. Assoc., Circ. 319, 585-96 (1927). (4) Stewart, J. R., Ibid., Circ. 378, 143-53 (1931).
RECEIVED July 19, 193.5.
M. R. ASWATHNARAYANA RAO AND BASRUR SANJIVA RAO Central College, University of Mysore, South India
Heatin circuit or rcifaq,,/
I
RIUCBJIVIUD July 18, 1935.
82.0 58.2 38.9 25.4
b Obtained by extrapolating the solvent power curve.
A Simple Automatic Cut-Off for Electric Stills
NTERMITTENT water supply in laboratories often causes the burning out of the electric heating unit of the apparatus for distilling water. An automatic cut-off, Supplied by the manufacturers of a certain still and involving the use of a float actuating a mercury switch, failed to work after use for a few months and caused in this laboratory the loss of the heating units of two stills. The stills are now fitted up with the simple automatic cut-off indicated in the accompanying figure. The glass parts are made of Pyrex and the electrodes dipping in the mercury are of nickel. The device is easily constructed and has been found to be extremely satisfactory.
SOLVES80
Benzene equivalent of standard solution, 113.8 cc.
100.0 85.2 66.0 47.4 34.5 25.4
Results with both solutions show very good agreement, the widest variation amounting to 0.8 per cent for the 60 per cent n-heptane blend. The kauri butanol values of certain hydrogenated products which contain some hydronaphthalene cannot be determined directly. This is caused by the fact that the gum, a t the end point of the titration, precipitates very slowly in the form of a transparent gel and therefore the prescribed end point in this method is not applicable. The solvent power of such products can be found only by determining the solvent power curve of a number of blends with n-heptane and obtaining the data for the pure solvent by extrapolation. The accuracy of this extrapolation method is shown by the results obtained with two hydrogenated solvents, Solvesso No. 2 and Solvesso No. 4. The solvent power curves of n-heptane blends with both solvents are shown in Figure 4 and the values given in Table IX, which shows a comparison of the solvent power of Solvesso No. 2 as directly obtained and also as found by extrapolation from the blending curve. The solvent power of Solvesso No. 4, however, can be obtained only by extrapolation and is included here only as a typical example.
2 100.0 93.9 85.0 60.0 49.8 25.4
Solution D Calculited
TABLEIx. SOLVENT POWERS O F %-HEPTANE AND BLENDS
% 100 80 60 40 20 0
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