998
INDUSTRIAL AND ENGINEERING CHEMISTRY
The solutions marked “unadjusted” in Table I were made up with tap water to the desired concentrations. I n the bactericidal tests, dilutions were also made with t a p water in order to approximate actual conditions of use.
Bactericidal Tests The technique used in carrying out the bactericidal tests was essentially that described by the United States Deparb ment of Agriculture (6). Eschericia coli and Staphylococcus aureus were used as test organisms. The sample solutions were made up to a given dilution with water of the same p H which had been adjusted with dilute sodium hydroxide and hydrochloric acid. The culture was adjusted to the pH of each test before use. I n testing mercurials, the retransferculture modification (6) was used. Controls of inoculated nutrient broth were run for each pH value tested. The results of these tests of standard pharmaceutical preparations are shown in Table I. The significant dilution figures indicate, respectively, the highest dilution of the compound that kills in 10 minutes but not in 5 at 20” C. and the lowest dilution that does not kill at either 5 or 10 minutes at 20” C. A consideration of the data presented in Table I reveals a general trend toward a definite increase in bactericidal effectiveness with an increase in the hydrogen-ion concentration of the medium. These results are in direct accord with the data obtained from similar studies of the phenylalkanoic acids (2) and of other commercial antiseptics (1, 5 ) . These studies also indicate that the hydrogen-ion effect may be independent of the molecular structure of the compounds. I n this work mercury derivatives, phenolic compounds, dyes, halogen compounds, and inorganic oxidking agents have been shown to exhibit similar increases in bactericidal action with increased acidity. Mercurophen and Mercurochrome could not be adjusted to the desired pH values on account of their incompatability with acids and alkalies, and hence these compounds were tested only as unadjusted. The pH effect on Amphyl is not clearly indicated by the results presented here. It seems t o show a maximum effectiveness a t a pH of about 7.
VOL. 32, NO. 7
An aqueous solution of mandelic acid was effective only in the concentration used a t the lower pH values. Sodium nitrite gave negative results in the concentrations tested. The behavior of potassium dichromate as compared with potassium permanganate is in direct agreement with the results of Newton and Edwards (4).
Summary The data in Table I indicate that the bactericidal action of Chlorazene, gentian violet, Listerine, Lysol, malachite green, mandelic acid, Pepsodent antiseptic, and potassium permanganate is enhanced by an increase in the hydrogen-ion concentration of the medium. This is in direct agreement with the results previously obtained with the phenylallranoic acids ( 2 ) and with other types of commercial antiseptics (1, 6). These data also add further confirmation to the validity of the hydrogen-ion effect postulated by Degering and co-workers ( 2 ) which appears to be effective for some organic mercury derivatives, phenolic compounds, some types of dyes, halogen compounds, inorganic oxidizing agents, benzoic acid, the alkanoic acids, other closely related compounds, and some inorganic salts. Amphyl seems to show its maximum bacteriostatic and bactericidal effectiveness a t a pH of about 7, and Sulphonmerthiolate is most suitable in alkaline media. Mercurochrome, Mercurophen, and zinc sulfate were tested only as unadjusted solutions, Acknowledgment This project was sponsored by the Mallinckrodt Chemical Works. Literature Cited (1) Bittenbender,
W. A,, Degering, E. F., and Tetrault, P. A.,
I N D .E N Q .CHEM., 31, 742 (1939).
(2) Goshorn, R. H., Degering, E. F., and Tetrault, P. A., Ibid., 30, 646 (1938). (3) Lundy, W.H., J. Bact.,35,633 (1938). (4) Newton, W., and Edwards, H. I . , Sci.Agr., 12,564 (1932). ( 5 ) Stern and Stern, J. Bact.,19, 133 (1930). (6) U. S. Dept. Agr., Circ. 198 (1931).
Nomographs for Correcting Volumes of Perfect Gases JACK G. ROOF, Oregon State College, CorvdIis, Ore.
I
N THE quantitative volumetric analysis of gases it is not
necessary that each gaseous volume be referred to the usual standard conditions of 0” C . and 760 mm. pressure. However, the successive volumes must be referred to the same conditions of temperature and pressure-conveniently, some arbitrary standard most prevalent in the particular laboratory. I n certain systems of gas analysis (e. g., the micromethod of Blacet and Leighton, S ) , the gas is always dry, so that the perfect gas equation can be used. Tables and graphs could be calculated showing the corrected volume for any temperature and pressure. Greater accuracy can be obtained if use is made of a set of corrections to be added to the observed volume to obtain the “corrected” volume. A quite complete chart was worked out by Barr (2).
Use of this particular nomograph involves making two successive settings of a straightedge and drawing one line parallel to another. Also the corrections scale is small, but a greater disadvantage is that, to use it, one would have to copy the nomograph as i t is or plot anew the markings on the axes if it is to be enlarged for greater accuracy in reading. I n this laboratory we have developed a pair of simple nomographs for volume corrections due to variations from our “standard conditions” of 22” C. and 760 mm. Each chart can be constructed in a few minutes on readily obtained graph paper, and the relative location of the axes requires only a single calculation of one correction for any convenient volume and pressure (or volume and temperature). It is readily shown mathematically that the construction
INDUSTRIAL AND ENGINEERING CHEMISTRY
JULY, 1940
999
.O
.O 0.6 60
i 754
0.4
766
+
6
.O
4
.O
3
.5
I 40
c-0.2
,
I
I
1
30-
i o 1 0
1
757
763
20
,o
2
I
!
U
0.021 0.01 6 9 4
10
I"
FIGURE 1. NOMOGRAPH FOR VOLUME CORRECTIONS DUE TO DEVIATIONS IN PRESSURE FROM 760 MM. AP and AV have the same sign. If P = 763 mm., add 0.24 unit to correct an observed volume of 60 units; if P = 757 mm., subtract 0.24 unit.
of such nomographs can be quite simple. Let letters with subscripts indicate quantities a t standard conditions and letters without subscripts be observed values. Then from Boyle's law: PoVo = PV = (Po
+ AP)(Vo -
.5
FIGURE 2. NOMOGRAPH FOR VOLUMECORRECTIONS DUE TO DEVIATIONS I N TEMPER.4TURE FRON 22" c. AT and AV have opposite signs. If T = 23" C., subtract 0.17 unit to correct an observed volume of 50 units; if 5" = 21' C., add 0.17 unit.
there is less chance of reading from the wrong vertical line. Good alignment is attained if we attach this center strip with Scotch adhesive tape, which causes little shrinking or distortion of the graph paper.
AV)
It can easily be shown that AV = V A P / P o
or, since POis a constant,
log A V
=
AV = kVAP log k log V
+
+ log
AP
This equation can be used to plot a nomogram of third order, genus zero (1). Since it is convenient to use equal ill moduli for log V and log AP, the modulus for log AV w be exactly half as great, and the support line for log AV w ill be parallel to the axes for log V and log AP and equidistant between them. Logarithmic paper is readily available in single-cycle and two-cycle forms-that is, paper in which the interval from 1 to 10 is the full size of the sheet, and in which there are two cycles (1 to 100) in the same linear space. If we place a strip of the two-cycle paper midway between the edges of a square of single-cycle paper, we have all the essentials for calculating corrections of this type. A single calculation will show how far up or down to move the center strip before attaching. For example, using a standard pressure of 760 mm., for V = 10 and AP = 1 mm., AV = 0.01316. Figure 1 is reproduced from a tracing showing the major lines of such a nomograph. Dotted lines indicate the edges of the strip cut from a piece of two-cycle paper. It is advisable to use one edge of a sheet of the two-cycle paper since the numbers can be placed on the blank margin, and
Directions are given for the construction of a pair of simple nornographs for correcting volumes of dry gases over small ranges of temperature (approximately 5' C.) and any range of pressure. Each chart is made from readily obtainable graph paper, and the construction requires only a single calculation of one volume correction for any convenient volume and pressure (or temperature).
A logarithmic scale cannot be extended to zero, but i t is easy to read corrections for any volume and any pressure from this chart (assuming the perfect gas law). Changing either AP or V by a factor of 10 will change the reading of A V by a factor of 10 in the same direction. However, one does not often use volumes less than one tenth of buret capacity, and the pressure so often falls more than 1mm. from standard. If the buret should have a total volume of 50 units, i t would be convenient to divide each number on the volume scale by 2 and have i t read (from bottom to top) 5, 10, . . ., 45, 50. This modification requires that the center scale be moved
1000
INDUSTRIAL AND ENGINEERING CHEMISTRY
upward until it reads correctly for some one calculated correction. Mathematical treatment of Charles' law will lead to volume corrections due to temperature changes : Vo= -V_ To
vo 4- AV
T - T o + AT
A nomogram similar to the previous one is constructed. For any ordinary room temperature changes it can be used to give corrections with a high degree of accuracy, although mathematically it is not exactly true. This is due to the term AT' subtracted from V in the last equation. This is not a serious error, however, for an increase of 3" C. from standard is a temperature change of only about 1 per cent. Thus there would be an error of 1 per cent in the volume correction, which is in itself only about 1 per cent of the
VOL. 32, NO. 7
volume. I n other words, the corrected volume would read about 0.01 per cent low, well within any limits of reading gaseous volumes in any analytical work. Even as drastic change as 5" C. would cause an error of only about 0.03 per cent. Figure 2 illustrates an alignment chart used in this laboratory to refer volumes to 22" C. For temperature changes of less than 0.5" C. i t is still usable, for changing AT by a factor of 10 changes A V by the same factor. When both ?' and P differ from standard, corrections are read from each scale and their algebraic sum is added to the observed volume.
Literature Cited (1) Allcock and Jones, "The Nomograph", Chap. 11, London, Sir Isaac Pitman & Sons, 1932. (2) Barr, G., J. Soo. C h . Id.,49, 21-3T (1930). (3) Blacet and Leighton, IND.ENQ.CHEM., Anal. Ed., 3, 266 (1931). PUBLISHED with the approval of the Monographs Publication Committee, Oregon State College. Research Paper 33, School of Science, Department of Chemistry.
Liquid-Vapor Equilibria of Furan Systems J
A. P. DUNLOP AND FLOYD TRIMBLE The Quaker Oats Company, Chicago, Ill.
-1TH the increasing market for furfural, furfuryl alcohol, and tetrahydrofurfuryl alcohol, i t seems desirable to extend our present knowledge regarding liquid-vapor equilibria of binary or ternary mixtures in which one or more of these products is present. With the exception of the data given by Mains (4) on the system furfural-water and by Lecat (2) regarding azeotropic mixtures, a survey of the literature revealed little information of this nature.
W
Procedure The furfural and furfuryl alcohol were prepared by fractionating the technical grade of each, three times under vacuum. The fractionating column was a well-insulated, 7-foot (2.13-meter) Hempel column, packed with 7-mm. glass Raschig rings. The apparatus was constructed entirely of glass, with ground-glass connections. Discards of approximately 15 per cent of the total volume were made a t t,he beginning and end of each distillation, and the mid-fractions which were used in this study boiled over a range of 1" C. The following physical constants were determined : Roiling range at 25 mm., C. Specific gravity, d:: Refractive index, ny Moisture (Bidwell-Sterling method) yo Acidity (chcd. as acetio acid), %
Furfural 64-65 1.1584 1.5255 0.0 0 002-0.003
Furfuryl Alcohol 83-84 1,1321 1.4868 0.0
0.002-0.003
The apparatus used for determining the liquid-vapor equilibria (Figure 1) was similar to that employed by Othmer ( 5 ) . Certain modifications were made, however-namely, trap F and condenser C'. The former was designed to
The System FurfuralFurfuryl Alcohol prevent the boiling liquid from surging over into the distillate receiver, and condenser C' was necessary to avoid undue losses of vapor when operating under vacuum. The furfural-furfuryl alcohol solution was boiled in still body A , the vapors passing through inner tube B and condenser C to be collected as distillate in receiver D. As the distillation proceeded, the temperature increased gradually until the contents of the receiver overflowed into the still body. At this stage the temperature decreased slightly as a result of the introduction of the distillate which was relatively richer in the more volatile component. Inasmuch as the overflowing distillate has the same composition as the vapors being evolved, the composition of the boiling liquid in the still body eventually reaches a constant value. When this condition is attained, the temperature ceases to fluctuate; but before the distillate is drawn off for analysis, the process is allowed to continue until approximately three times the volume of receiver D has overflowed into the still body. The distillate was then assumed to be representative of the vapor which existed in equilibrium with the liquid composition. At no time was the volume of liquid in still body A less than 250 cc., and the volume of distillate collected was approximately 10 cc. The pressure was maintained a t 25 mm. of mercury by means of a Hyvac pump which was connected to the top of condenser C'. A preliminary investigation of the system when distilled at atmospheric pressure indicated that prolonged heating had a n adverse effect on solutions of furfural and furfuryl alcohol as measured by refractive index. The magnitude of this effect is shown in Table I and Figure 2, the data being obtained by refluxing solutions of known concentration a t atmospheric pressure for the indicated time.
9
