ANALYTICAL EDITION
408 TABLE
v.
ANALYSIS OF GASES ENTERING AND
ABSORPTION PLANT
LEAVING
AN
(Gallons of gasoline per 1000 cubic feet of gas) GASENTBRINQ SAMPLE ABSORPTION EXHAUST APPROXIMAT. No. TOWER GAS RZCOVERY 1 0.26 0.08 0.2 2 0.34 0.16 0.2 2 0.35 0.16 0.2 3 0.43 0.12 0.3 4 0.92 0.21 0.7
samples were taken of the plant gases entering the absorption system and also of the exhaust gases leaving the plant.
Vol. 6, No. 6
The difference between the gasoline content of the exhaust gases and that of the gases entering the absorption system was in close agreement with the quantity of gasoline collected from the absorption. LITERATURE CITED (1) Tropsoh and Mattox, IND.ENQ. CHEM.,Anal. Ed., 6, 235-41 (1934). ( 2 ) Tropsoh and Mattox, Universal oil Products Booklet 138 (1934). R ~ C ~ I VJune E D 22, 1934.
Determination of Tie Lines in Ternary Systems Without Analyses for the Components THEODORE W. EVANS,Shell Development Company, Emeryville, Calif,
T
ERNARY liquid systems are generally characterized
by plotting on a triangular field the curves separating the regions of homogeneity and heterogeneity, together with the tie lines connecting the points representing conjugate phases. The boundary curves may usually be easily obtained by titrating a homogeneous mixture of two of the components with the third until turbidity appears, thereby securing one point. To determine the tie lines, however, no simple method, except that of Miller and McPherson ( I ) , seems to have been developed that does not require a direct
two layers, the composition of the lower layer being represented by a point on, say, the left-hand portion of the curve, the upper layer on the right-hand side. The line joining these two points is a tie line and passes through P. Through P draw the lines IPJ, KPL, and MPN. Ordinarily the composition of lower and upper layers can be estimated roughly and the lines drawn so that these compositions lie somewhere between I and M , and J and N . Assume this is the case here; in case it is not, the discrepancy will appear later and if necessary one of the lines can be changed accordingly. Let ml, m2 be the weights of the upper and lower layers obtained, mA, etc., the weights of the components taken, and L A , etc., the percentage of component A corresponding to the point L. In case KPL is the true tie line we have o.Ol(mlL~f m2KB) = ma. In general KPL will not have been so chosen as to be the exact line, and hence O.Ol(rnlL~ ~ K Bwill : not equal me. However, by plotting the value of this expression for the three lines drawn against the percentage B of the points on the right-hand branch of the curve or the percentage A on the left branch, a value of these percentages will be obtained for which the expression does equal mB. By now e5 locating this point on the curve and joining it to P the tie line is secured. In the s a m e w a y t h e percentage A could have been used. The essential point to the process is that as we proceed I from I to M the-percentage B does not change 65 70 % 5 CORRFSPONDiNG TO J, L, ETC. greatly, and what change there is is in a positive FIGURE 2 direction, while from J to N the change is very rapid and positive, thus making the method relatively sensitive. It is evident that the C component would not be suitable, since it increases from I to M and decreases about equally from J to N , the two effects offsettingeach other and rendering the variation in 0.01 (ml& m2Kc)too small to be useful. The following example will illustrate the met hod.
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2
FIGURE 1 analysis for at least one of the components (8). Inasmuch as systems are often investigated in which none of the components can be accurately or easily determined it is desirable to have some rapid method of determining the tie lines which is independent of chemical analyses. The following method seems new, is applicable in the usual cases, and compares favorably with that of Miller and McPherson in ease of manipulation. In Figure 1 is shown a typical ternary diagram for the system of three components A , B, and C. Suppose weighed amounts of the three components are now taken in such amounts that the over-all composition is represented by the point P. Thi8 mixture upon shaking and settling will give
75L
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November 15,1934
I N D U S T R IA L A N D E N G : N E E R I N G C H E M I S T R Y
A mixture of 84.5 grams of A, 80.5 grams of B, and 46.5 grams of C is shaken and on settling is found to give 122.5 grams of upper layer and 59.0 grams of lower layer. Point P in Figure 1
represents this over-all composition-namely 40, 38, and 22 per cent. Now if I P J were the true tie line, the mass of B should be 0.01 ((89.0)(1) f (122.5)(62.5)] = 77.4 grams. Similarly K P L demands 80.9 grams and M P N 89.0 grams, whereas the true line should give the amount of B originally taken, 80.5 grams. By plotting these values against the percentage B represented by the points J, L, and N , the percentage corresponding t o a value of 80.5 is found to be 64.7 (Figure 2). This percentage when located on the curve of Figure 1 indicates that the upper layer obtained above is 3 per cent A , 64.7 per cent B, and 32.3 per cent C. By joining this point to P the tie line is obtained. As a check on the work, the above process can be repeated on component A , this time locating a point on the left side of the curve which when joined to P gives the tie line. If both times the same tie line is obtained, one can feel sure of the accuracy of the work. In the present case the percentage A is found to be 91, thus locating the oint on the curve 91 per cent A, 1.5 r cent B, 7.5 per cent C! This also lies on the tie line secured 9”y computing on the basis of component B, thus checking the previous work. Finally, using the values so obtained for the ercentage C in each layer, it is found that on this basis we should gave started with 0.01 [(89.0)(7.5) (122.5)(32.3)] = 46.3 grams
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409
of component C, which is in satisfactory agreement with the 46.5 grams actually taken.
I n the present case the auxiliary lines IJ, etc., were so drawn that they lay on either side of the tie line. I n case they had been so chosen that they all lay on the same side of the tie line, this fact would have instantly appeared on graphing the expression O . O ~ ( ~ J B ~ J B since ) , it would have been greater (or less) than m~ for all the lines instead of greater for one and less for another. In many cases the graph could still be successfully extrapolated. If the extrapolation seemed uncertain, then another line could be chosen so as certainly to lie beyond the tie line, and by adding this value to the graph the required value easily determined by interpolation.
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LITERATURE CITED (1) Miller and Mopherson, J . Phys. Chem., 12, 710 (1908). (2) Roozeboom, H. W. B., “Die heterogenen Gleiohgewiohte,” Vol. 3, Part 2, pp. 87-95, Friedr. Vieweg & S o h , Brauneohweig, Germany, 1911. R ~ C ~ I V May I U D22, 1934.
Chemical Studies of Wood Preservation 111. Analysis of Preserved Timber ROBERTE. WATERMAN, F. C. KOCH,AND W. MCMAHON,Bell Telephone Laboratories, New York, N. Y.
I
expensive in order to permit N T H E study of the preserMethods are given for analysis of preserved the examination of a substanvation of poles, one may distimber, creosoted or treated with inorganic tial proportion of all the poles tinguish s e v e r a l kinds of sails. The methods are in part adapted for a n d t h e d e l i v e r y of t h e res a m p l e s for chemical analysis aPPraisal O f freshly treated poles f o r quantity and sults of analysis within a few classified according $0 the purexcellence of distribution of preservatiw and in hours. pose of the study: In order to d e t e r m i n e t h e part adapted to following the processes of deple1. Samples of freshly treated Penetration and retent of the timber taken for the purpose of tion during years of exposure. Recovery of d e t e r m i n i n g the quantity of a individual poles in any particuCmXote from old t h b e r (-2nd for the known preRervative and the lar charge, it would be necescharacter of its distribution. analysis and toximetry of creosote are described. sary to take s e v e r a l b o r i n g s 2. Samples from poles still around the circumference of each r e q u i r e d for service or further exposure in experimental plots. These samples may be used t o pole and perform an analysis on the composite borings from determine roughly the changes in quantity, distribution, and each pole separately. Except for very special purposes this is toxicit of preservatives with time. 3. gamples of poles which have been removed from service too laborious. A sing1e boring from each pole will suffice to lines or from experimental plots and are therefore available for give a fairly good appraisal, provided each boring is examined more thorough study of the changes in properties of preservatives for depth of sapwood and depth of penetration as well as with the lapse of years. preservative content. A great deal can be learned by sampling only a selected proportion of the poles. The borings It is the Purpose of the Present Paper to outline the analfli- may be split for analysis as described in a previous paper (Q), cal methods used for the examination of the foregoing classes though for some purposes the whole boring may be analyzed of samples. While these studies are primarily concerned with and an empirical correction or an arbitrary standard of creosote, the authors have examined many other preserva- preservative content may be applied. tives Inore O r less thoroUghlY. For this Purpose it has been In the case of freshly creosoted poles the following method necessary to devise special analytical methods in certain cases. of determining creosote has been found convenient: ANALYSIS OF FRESHLY TREATED TIMBER The purpose of an examination of freshly treated timber is usually to secure some measure of the excellence of a treating process at a particular plant or by a particular method. this case a sample of the original preservative is available for thorough examination of its physical and chemical properties as well as toxicity. Since i t is unnecessary to recover the preservative from the samplesin its original state, one has a freer choice of analytical methods. It iS Often highly deskable that the method of analysis of wood be rapid and in-
The heartwood and untreated sapwood are broken off the borings, and the samples thus obtained are chipped up and placed in a tared brass container provided with a screen bott,om and weighed. This container is then placed in the apparatus shown in Figure 1. The solvent, which may be either toluene or xylene, is boiled, and as the vapors extract the wood, the water is carried UP into the condenser and drops into the calibrated trap, The extraction is continued until the solvent dripping from the cage is colorless and water ceases to drop into the trap. The solvent is evaporated from the extracted wood, which is then brought to constant weight at approximately 105’ C. The water content i8 read directly in the trap. The weight of water plus the dry weight of wood subtracted from the original weight
