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INDUSTRIAL AND ENGINEERING CHEMISTRY
( 5 ) Mohlman, F. W., Sewage Works J.,4, 899-900 (1932). E.B., e t al., Zbid., 5, 579 (1933). (7) Theriitult, E.J., Suppl. Pub. Health Repts. 90 (1931). (8) Theriault, E. J., MoNamee, P. D., and Butterfield, C. T., Pub. Health Repts., 46, 1084-1116 (1931); Pub. Health R e print 1475.
(6) Phelps,
Vol. 26. No. 5
(9) Townsend, D.W., Munic. Sanit., 3,18 (1932). (10) Viehl, K., Zentr. Bakt. Parasitenk., II,86, 34-43 (1932). RECEIVEDJanuary 22, 1934. Presented before the Division of Water, Sewage, and Sanitation Chemistry e t the 85th Meeting of the American Chemical Society, Washington, D. C.. March 26 to 31, 1933.
Porter's Rule Graphical Analysis of Viscosity-Temperature Data for Solutions of Electrolytes A. M. RENTEAND F. E. SEUFFERT, Wayne University, Detroit, Mich. HE viscosity of liquids and solutions is an important fate a t 43" C., start at the isoviscoidal temperature of 43" and factor in the flow of fluids. Important as it is, the ex- follow the dotted line to B. At this point the viscosity of the istent data concerning viscosity of solutions of elec- potassium sulfate solution is the same as that of pure water at trolytes are meager. In this paper it is proposed to extend 52" C. Therefore, the intersection point of the 52" C. temPorter's method for estimating unknown viscosities of solu- perature line of pure wat,er with curve A will determine the tions a t a given temperature when the viscosity is known a t viscosity in poises of the potassium sulfate solution at 43" temperature. some other temperature. To develop the statement that "the isoviscoidal lines for a Duhring's rule (1) states that, when the temperature of one substance is plotted against the temperature a t which a second series of concentrations of a certain substance are straight s u b s t a n c e h a s the lines," the viscosity data of fifteen electrolytes have been f-9 same vapor pressure studied. It is realized that fifteen electrolytes are not enough :.0/6 $ as the first, the result to establish a positive generalization, yet they are sufficient 60e will be practically a to indicate a characteristic trend. In all cases the data have %2 straight line. This been taken from a reliable source (2). Also, the plotting of all graphical charts was done on a very large scale, 1" C. being ? 404 rule applies both to kOO8 pure l i q u i d s and to measured by a distance of 25.4 mm. (1 inch). z r ~ g solutions of electroThe isoviscoidal lines for the fifteen substances investi$ 2 lytes. Porter (3) ap- gated are straight lines, and with but six exceptions these 0 plied this idea to or- lines meet in a common point. Further, this point often 20 40 60 80 ganic l i q u i d s a n d lies on, or near, the diagonal Y = X . One of the six excepT E M R O f WATER OC showed that viscosity tions-potassium chloride-gives four lines that may be said FIGURE1. DIAGRAM OF PROCEDURE could be substituted to intersect a t (25, 25). A fifth line (for the concentration FOR DETERMINING VISCOSITY for vanor Dressure. and the result, as before, mould be a straigdt line. Since isoviscoidal means equal viscosity, the name "isoviscoidal lines" will be given to u' 60 0 these Porter lines. It will be shown that the isoviscoidal lines 2'40 4 for a series of concentrations of a particular 0 electrolyte in water are straight and that in v) 20 most cases these lines meet in a common point. Lc Whenever this common point can be located, it 0 0 may be used to locate any number of lines of different concentrations of the same salt. It $-Z0 is necessary to know merely one point on the k! unknown isoviscoidal line; by joining this point -EO 0 20 40 60 -40 -20 0 20 40 to the common point, the line is determined. This line, then, indirectly expresses the relationship between temperature and viscosity for 60 that concentration of the solution it represents. 640 This method is only approximate, but is graphi0 40 cal and should be sufficiently accurate for engi$2 0 neering calculations. 4 0 20 The procedure used for determining viscosity Y O is i l l u s t r a t e d in Figure 1 and is the same method as that described by Walker, Lewis, 4j 0 -ZO and McAdams (4). A is the viscosity us. temperature curve of pure water (2). The righte-40 $ -2 0 hand ordinate represents the temperature a t which a solution must be in order to have the -20 0 20 40 -20 0 PO 40 60 same absolute viscosity as pure water a t some ZSOV/SC O/DAL T E M ~ , ~ . IS OV/SCO/DAL JEMR, OC. particular temperature. For example, to determine the viscosity of 0.979 N potassium sulFIGURE 2. GROUPINGS OF ISOVISCOIDAL LINES
T a
8
May, 1934
I N D U S T R I .4 L A N D E N G I N E E R I J’T G C H E M I S T R Y
of 2.5 F) does not meet the others a t this common point. However, this line like all the others is a straight line. I n the case of nitric acid, the isoviscoidal lines for concentrations of 0.1, 0.25, and 0.5 F meet a t (11.0, l l . O ) , while the line for a fourth concentration-1.0 F-fails to do so. Sodium iodide, ammonium bromide, ammonium dichromate, and sodium bromide are the other salts whose solutions do not give isoviscoidal lines that meet in a point. However, for any one concentration of any of these four salts the isoviscoidal line is straight. The viscosity of liquids is affected by association and dissociation, and Porter’s rule applies only when there is no increase or decrease in the degree of association of the molecules in a solution. The degree of association is markedly different in solutions of extremely high or low concentrations. Consequently, solutions whose molecules change their degree of association with variation in concentration will not follow the isoviscoidal rule when quite dilute or highly concentrated. These considerations may explain the exceptions to the general rule that were noted. Figure 2 shows the different groupings taken by the isoviscoidal lines. In Figure 2, F is the concentration in formula weights per 1000 grams of water. For sodium chloride the isoviscoidal point is on the diagonal Y = X, a t the same time being below zero. The lines for sulfuric acid show the isoviscoidal point also to be below zero but not on the diagonal Y = X . Data for sodium iodide show a case where the isoviscoidal lines do not meet in a point. The point for cesium
551
nitrate is above zero and lies very close to t.he diagonal Y = X. Cesium nitrate is one of the salts which decreases the viscosity of water, as does potassium chloride. Below are listed the Y and X coordinates of the isoviscoidal points for the aqueous solutions studied: None None
RbzSOi
( - 2 3 , -23) ( + 6 7 , f67.5) (-2.75, -2.75)
None None (-15, -15)
NaBr NaCl NaI NaNOa SrClz
(-7.
None
-7)
( - 3 3 , -33)
None
( - 5 1 , -56) ( - 4 3 , -45) ( - 4 5 , -48)
Porter’s lines (isoviscoidal lines) for various concentrations of solutions of a given electrolyte have been shown to be
straight lines and, in general, when extended, to meet in a point. I n many cases this point lies on, or near, the diagonal Y = X. A method determining the viscosity us. temperature relationship of a particular concentration of an electrolyte has been developed. LITERaTURE CITED
(1) Duhriny, “Neue Grundgesetre rur nationelle Physik und Chemie,” Erste Folge, Leiprig, 1878. (2) International Critical Tables, Vol. V pp. 13-18. McGraw-Hill, New York, 1929. (3) Porter, A. W., Phil. Mag., 23, 458 (1912). (4) Walker, Lewis, and McAdams, “Principles of Chemical Engineering,” p. 82, McGraw-Hill, New York, 1927.
RECEIVED August 15, 1933.
Lacquer Development during 100 Years D. R. WIGGAM ANI) W. E. GLOOR, Hercules Powder Co., Wilmington, Del. HE year 1933 marked riot only the Chicago Century of Progress, but also a century of progress in the development of cellulose lacquers. Just a hundred years ago Braconnot (4) published his account of the preparation of xyloidin by treating starch, sawdust, cotton, etc., mith nitric acid and washing. This material proved soluble in acetic acid or pyroligneous acid, from which “a hard varnish-like film” could be obtained on evaporation. Braconnot also found this film to be water-resistant and actually tried to make small microscope lenses from it, as it was “colorless as white glass, and keeps its clarity under water.” Here we have the genesis of both the plastic and lacquer industries. Braconnot’s work did not receive wide attention a t the time, but Liebig recognized its fundamental importance and in a footnote to a translation of Braconnot’s article (5) he described certain of his own experiments showing the instability of the material and recognized the need of further analytical data before xyloidin could be callecl a compound of nitric acid. Boettger (3)reported negative results in attempting to make the material, but Pelouze, one of Braconnot’s assistants, provided further experimental data (30). He nitrated starch and paper with nitric acid of 1.5 specific gravity and was the first to affirm that these materials actually reacted as “bases toward the acid.” While he suggested the possibility of use of this material as an explosive, it was some time later before this observation was made use of. Schonbein (33) was the first to nitrate cotton and starch with mixed sulfuric and nitric acids, a step which first rendered the commercial production of nitrocellulose practical. He was primarily interested in the use of these materials in explosives, and between Schonbein’s work, the announcements of Boettger and Otto that they too had made guncotton, and the controversy with Pelouze over priority of discovery,
T
Braconnot’s description of varnish-like films was apparently overlooked. However, Schonbein had used solutions of his guncotton in ether-alcohol as an “ether glue” (4). Maynard (25) proposed the use of ether-alcohol solutions of nitrocellulose in a surgical dressing. This was the first solvent combination available, and for nearly 40 years inventors tried to overcome its volatility and hygroscopicity. With the contribution of Abel (1) who stressed the importance of using pure raw materials as well as the careful purification of the nitrated product and who developed a satisfactory test for stability, the art of nitrating cellulose became firmly established. The plasticizing value of such materials as castor oil (29)and camphor (18)was discovered. A clear recognition of the desirability of mixing gunis and plasticizers with nitrocellulose to produce varnish-like materials for protective coatings seems to be due to Parkes ($8) ; however the practical application of this idea had to await Stevens’ disclosure (39) of amyl acetate as a nitrocellulose solvent in 1882 almost 50 years after Braconnot. With this slow-drying nonhygroscopic solvent, the way toward the working out of the technical details of Braconnot’s ideal was cleared. Amyl acetate lacquers, first developed by Hale and Crane (43),proved to be good metal finishes and vehicles for bronze. This commercial success undoubtedly stimulated the research which led to the discovery of the solvent properties of ketones, esters, and a host of new plasticizers. Important in this period, Crane’s use of acetone oil as a solvent (9), the disclosure of some two hundred esters as solvents by Nobel, the use of benzene and petroleum hydrocarbons as cheapening diluents, and the discovery of the plasticizing value of phthalates (20) and phosphates (46) are all essential steps in the development of lacquers.
