August, 1930
I.!’DCSTRIAL AND ENGINEERIiVG CHEMISTRY
a more efficient method for the uniform contact of air and acid on the tin-plate material being detinned. Attempts were made to detin the scrap by spraying with dilute tartaric acid solution. The tin was dissolved a t a fairly rapid rate, but the method was considered unsuccessful because considerable solution was lost by dispersion of the solution into the atmosphere. A more efficient method for detinning was perfected in which the scrap was placed in a cylinder,. partially submerged in dilute tartaric acid solution. A detinmng apparatus consisting of a perforated steel cylinder 6 inches in length and 33/4 inches in diameter and a detinning tank 71/* inches in length and 5 inches in width was constructed. The cylinder, containing the tin-plate scrap, was turned on a 1/4-incli steel shaft which passed through the length of the cylinder and detinning tank. I n the process of detinning the solution level is regulated to cover about one-third the cross-sectional area of the cylinder. The scrap contained in the cylinder is thus subjected to the alternate action of acid and air. Three hours was found the most efficient length of time to conduct detinning and the acid was most effective a t 5 per cent concentration. The solution after detinning, contains stannous tartrate. The tin may be recovered from the polution by precipitation
911
as sulfide with hydrogen sulfide. The tin from stannous tartrate is replaced by the hydrogen from hydrogen sulfide and tartaric acid is recovered. There is a slight loss of tartaric acid in this reaction owing t o decomposition, which is about 0.10 gram of acid per gram of tin recovered. The tin sulfide may be converted into the chloride by treating with hydrochloric acid. The detinned scrap contains about 0.10 per cent tin, which is sufficiently low to be suitable for steel smeltering. In the detinning of old tin cans it would be necessary to clean the cans first with hot sodium hydroxide or carbonate ( 1 ) . The presence of grease and lacquers will inhihit the action of tartaric acid on tin. The cost of detinning tin-plate materials by the method outlined above, since it has been attempted only on a laboratory scale, cannot be accurately estimated. The equipment necessary to conduct detinning with tartaric acid method is simpler than that required in the chlorine and alkali processes and would be less expensive. The cost of acid consumed, as determined in our investigation, is 3.7 cents per pound of tin recovered. Literature Cited (1) Butterfield, U S Patent 1,511,590 (December 15, 192&).
Properties of Shellac Films I-Resistance of Shellac Films from Various Varnishes to Action of Water and Chemicals‘ M . Venugopalan and M. Rangaswami INDIAN LAC RESEARCH IXSTITUTE. NAMIUMP. O . , RAXCHI,B . hT,R Y . , IXDIA
vv
‘ITH the view of stabilizing the use of shellac in the varnish industry, the action of different solvents for making shellac varnish was investigated. (Bulletin No. 1, Indian Lac Association for Research, 1928) The effect of common alcohols, such as methylated spirit and wood naphtha, on the viscosity and solvent power of the solution has already been reported ( 1 ) . It was found that wood naphtha exhibited the peculiarity of combining the two essential properties of a varnish solvent, high solvent power and low viscosity, at a particular concentration, and this was considered to Le due to the complex nature of this solvent. This work was followed by a study of the effect of binary mixtures of some common solvents with reference to these two properties ( 2 ) . Three types of mixed solvents of varying proportions were tested-i. e.. alcohols and alcohols, alcohols and esters, and alcohols and ketones-and from a study of these two properties it was possible to compare the efficiency of the different mixtures in terms of the ratio of the solvent power number to the relative times of flow. I t was found from these figures that, except in the case of alcohols and esters, a mixture of two solvents always shomed a higher efficiency than either solvent taken singly, and a mixture was found in most cases which showed the maximum efficiency. Furthermore, in the case of ethyl alcohol-ethyl acetate mixture and more particularly of mixtures of alcohols and acetone, the mixed solvent proi-ed to be more efficient than the pure alcohol, though the mixture contained a nonsolvent for shellac. I n view of the lorn price of acetone compared with that of alcohol, the economic advantage of employing the optimum mixture of the two in preference to the pure alcohol was indicated. 1
Received April 29. 1330.
It was, however, considered essential to examine the quality of the films obtained from these mixtures, and in this paper the resistance of the films from various solutions to the action of water and such chemical agents as acids and alkalies has been discussed. I n these tests only those mixtures have been used which proved to be the optimum mixture of two solvents in the prerious work, together with the three alcohols for comparison. Preparation of Varnish Films
The varnish was prepared by dissolving 50 grams of specially made “Lvax-free” shellac in 100 cc. of the solvent in the cold with the aid of shaking Films were prepared on glass slides by pipetting 2 cc. of the varnish onto the center of the slide and spinning the latter on a turntable at 300 r. p. m. The films were then dried for a week before testing. Owing to the different viscosities and densities of the various varnishes, different film thicknesses were obtained, but as the object was t o study the behavior of the different solvents under identical conditions, no attempt was made to get identical thicknesses by varying the speed and duration of spinning. Only in two cases, however, were extremely thin films obtained (Table I). Table I-Thickness
of F i l m s from Various Yarnishes MEANFILM
SOLVE\T COYPOSITIOh
Methyl alcohol Ethyl alcohol Propyl alcohol Methyl alcohol-ethyl alcohol, 1 . 1 Methyl alcohol-propyl alcohol, 3 : 1 Ethyl alcohol-ethyl acetate, 3 . 2 Methyl alcohol-acetone, 3 : 2 Ethyl alcohol-acetone, 2 3 Ethyl alcohol-ethylmethyl ketone, 1 : 3
THICKNESS Mwons 46 50 20 50 50 21
57
54
57
IhTDUSTRIAL A N D ENGINEERING CHEMISTRY
912
Effect of Water
Duplicate specimens from each set were steeped in distilled water and examined at the end of 24 hours, 48 hours, and 1 week, as to the amount of water absorbed by the various films and the effect on their structure. Table 11-Absorption
of Water b y Various Films (Based on weight of dry film) SOLVENT COMPOSITION 24 HOURS 48 HOURS 1 WEEK Per cent Methyl alcohol 2.2 Ethyl alcohol ? Propyl alcohol 13.8 Methyl alcohol-ethyl alcohol 1 : 1 3.3 Methyl alcohol-propyl slcoh6.l 3:1 1.8 Ethyl alcohol-ethyl acetate, 3(2 2.0 Methyl alcohol-acetone, 3:2 2.5 Ethyl alcohol-acetone, 2:3 2.8 Ethyl alcohol-ethylmethyl ketone, 1:3 3.7
Per cent 3.2 5.4 24.7 11.3 12.8 6.2 5.6 5.4 7.8
Per cent 8.1 11.3 56.3 13.5 30.2 14.4 11.5 12.0 18.0
I n Table I1 it is seen that only propyl alcohol and its mixture with methyl alcohol give films of considerable waterabsorbing capacity, though the latter does not compare badly in the 48-hour test, especially with the methyl alcoholethyl alcohol mixture. The mixed solvents including acetone, however, compare very well with ideal solvents like methyl and ethyl alcohol. All the films turned white and lost their transparency in the 48-hour test. The two thin films-those from propyl alcohol and ethyl alcohol-ethyl acetate solutions-showed much earlier and more pronounced blushing than the others, losing their transparency in about 2 hours and turning more or less completely opaque at the end of the test. Fine checking was observed under the microscope in every case with minute particles of water confined between the breaks. However, with the exception of ethyl alcohol-ethyl acetate, the films from the mixed solvents were somewhat less affected than those from the single solvents. On removal from water all the films regained their transparency and original structure in 18 to 24 hours, and the two thin films recovered in about 4 hours. Water had, therefore, no permanent effect on the tilms in 48 hours. It was noticed, however, that in the case of certain fJmse. g., that from propyl alcohol-the whitening persisted at the edges, where the film was thicker, even after drying for a long time. This seemed to have been a permanent change, probably a hydration of the resin-water having been tenaciously held by the film. I n the 1-week test no outstanding difference was shown between the effects on different films. All the films lost their transparency and turned more or less completely opaque. Blushing and checking were noticed, the ketone mixtures being least affected. Many fine air holes had developed owing to the wearing away of the film in places, the methyl alcohol-ethyl alcohol mixture and the acetone mixtures again coming out better than the others. Chalking was exhibited by films from methyl alcohol-propyl alcohol and ethyl alcohol-et hylmet hyl ketone mixtures . These effects were reversible except for the chalking and air holes, which remained permanent. The films regained their color and transparency in 18 to 36 hours, the thinner films recovering first. The whitening a t the edges shown by many films, more conspicuously by those from varnishes containing propyl alcohol, did not, however, disappear even after prolonged drying. The ketone series showed practically no defect of this kind. Effect of Brine
After having studied the effect of pure water on the films, it was proposed to see how they were affected by sea water, as when they are used to coat a ship's parts which are continuallp under the sea. This effect was imitated by immersing the test specimens in a 3.35 per cent solution of a mixture
VOl. 22, No. 8
consisting of sodium chloride 75, potassium chloride 4, magnesium chloride 10, calcium sulfate 5, and magnesium sulfate 6 per cent, which closely approximates the average composition of sea water. Though it was expected that there would be greater corrosion of the films by brine than by pure water, it was observed that the films were very little affected by sea water even at the end of several weeks. Effect of Acids
Test specimens were immersed in 1 N sulfuric acid at 27" C. for 1 hour. At the end of this time all were unaffected, though the usual test is to keep the film immersed in 0.5 N sulfuric acid for only 15 minutes. The test was, however, continued for 24 hours and still all the films were found to be intact. This acid has, therefore, a t this strength no effect on the films. Effect of Alkalies
The test pieces were immersed in 1 per cent caustic soda solution for 2 and 5 minutes, respectively, in two series of tests. I n the 2-minute test propyl alcohol showed up very badly, the film having been dissolved out except at the edges. The ethyl alcohol-ethyl acetate film, which was as thin as the propyl alcohol film, lost its gloss and transparency and became patchy. Films from solutions in methyl alcohol, methyl alcohol-acetone, and ethyl alcohol-ethylmethyl ketone were affected only to the extent of a slight loss of gloss, and those from solutions in ethyl alcohol, methyl alcohol-ethyl alcohol, and ethyl alcohol-acetone were completely unaffected. I n the drastic 5-minute test most of the films were broken down, some being completely dissolved out by the alkali and others sloughing off and partially dissolving, exposing the glass surface here and there. Of the single solvents only the film from ethyl alcohol solution stood the test comparatively well, showing only a few patches of exposed glass. Among the mixed solvents the methyl alcohol-acetone film resisted the action best, showing neither solution in the alkali nor sloughing off, and the film from ethyl alcoholacetone solution escaped with a slight sloughing and a little patchiness, without, however, the destruction of the film structure. Effect of Alcohol
The films were immersed in 15 per cent ethyl alcohol for 15 and 30 minutes, respectively, in two series of experiments. After the 15-minute test all the films were found in good condition except those from varnishes containing propyl alcohol, which suffered from checking and a slight loss of transparency. When the test was extended to 3C minutes, some of those which had stood the previous test well were slightly affected in a similar way, but films from ethyl alcohol, methyl alcohol-acetone, and ethyl alcohol-acetone entirely resisted the action. Effect of Gases
Only two common gases-sulfur dioxide and ammoniawere tried. The samples were put in an empty desiccator, which was then filled with the gas and kept for 48 hours before examination. None of the films were affected by sulfur dioxide either in appearance or in structure. Ammonia, on the other hand, turned all the films pink, owing evidently to its action on erythrolaccin, which is the coloring principle of the resin in shellac. There was no effect on the transparency or structure of the films and even the color change was found to be temporary.
INDUSTRIAL AXD ENGINEERTXG CHEMISTRY
August, 1930
Conclusions
Two points will become evident as a result of these tests. The films from varnishes containing mixed solvents are in general less affected than those from varnishes prepared from a single solvent from the point of view of their resistance to water and the chemicals tested. Secondly, of the mixed solvents studied, mixtures of methyl or ethyl alcohol with acetone are best adapted for varnish making, since the varnishes prepared from these not only show higher solvent power and lower viscosity than the varnish from the standard
913
solvent, ethyl alcohol, but also produce films which are most resistant. Further tests are being made on the mechanical properties of the films from these varnishes and weathering tests will presently be instituted with panels coated with the different varnishes in order to see how they withstand a prolonged exposure to sudden changes of weather. Literature Cited (1) Indian Lac Assocn. for Research, Bull. 1 (1928) (2) Ibid., Bull. 2 (1929).
Knock Rating of Straight-Run Pennsylvania Gasoline in Relation to Boiling Point, Density, and Index of Refraction' Preliminary Note M . R. Fenske T H EPENNSYLVANIA STATECOLLEGE, STATECOLLEGE, PA.
T
HE object of the present work was to fractionate Pennsylvania straight-run gasoline more thoroughly than has been done before. For this purpose a fractionation column of 3-inch (7.6-cm.) iron pipe, 35 feet (10.7 meters) in height, has been constructed. It was packed with alternate 6-inch (15-cm.) sections of l/r-inch (6-mm.) glass rings and iron jack chain. The column during operation was made as near as possible adiabatic by means of electric winding in several sections. The head of the column was arranged to give any desired reflex ratio. Thermocouples inside the column and in the insulation made possible the control of heat losses during the distillation. R e l a t i o n b e t w e e n Knock R a t i n g a n d O t h e r Properties of StraightR u n Pennsylvania Gasoline REFRACTIVE KNOCK BOILING POINT DtSTILLED DENSITY INDEX RATING^ Per cent F. c. 22 1 3760 -0.2 110 43.3 0.654 145 62.8 0.678 1 3850 26 3 0 + 173 78.3 0.725 1 4055 29 0.0 193 89.4 34 0.701 1 3960 1.7 202 94.4 37 6.6 0.711 1 4020 213 100,6 43 0.770 1 4305 t 0.2 235 112.8 47 0.725 1 4080 4.0 240 115.5 50 8.7 0.730 1 4090 t 240 115.5 53 0.727 1 4070 16.5 270 132,2 0.786 1 4430 0.17 58 64 300 148.9 0.742 1 4155 17.2 70 325 162.8 0.780 1 4370 t 3.8 75 343 172.8 0.759 1 4260 39.0 78 365 185.0 0 . 7 7 8 41 4350 16 8 82 380 193.3 0.773 1 4325 29.6 83 385 196.1 0.776 1 4345 34.8 85 400 204.4 0.788 1 4390 -t 26.0 0 With the exception of the first fraction the values given are the number of cubic centimeters of lead tetraethyl er gallon required t o bring the fraction t o the Ethyl Gasoline standard. %he negative value for the first fraction indicates that it is slightly better in knock characteristics than the standard.
-
+ + + + +
-+ -+
+
+
++ + + +
Crude petroleum from the flooded wells in Bradford, Pa., was selected for the study, since this represents the largest Pennsylvania production a t this time. Crude from a typical individual well was used. This was topped without the use of a column to obtain 9 gallons of straight-run gasoline boiling up to 265" C. (510" F.). This straight-run gasoline was then distilled in one batch, using the %-foot (10.7meter) column. The distillation occupied 45 hours. About 16 per cent of the gasoline consisted mainly of butanes and 1
Received July 21, 1930
pentanes. These were condensed by means of Dry-Ice. The gasoline boiling 43-206" C. (109-403" F.) was separated into 165 fractions. I n many cases several fractions were taken, all boiling a t practically the same temperature. The densities and refractive indices were taken on each fraction. Typical fractions were tested for knock characteristics by the bouncing-pin method with an engine procured from the Ethyl Gasoline Corporation. I n some instances where several fractions were taken a t the same temperature (within 1O F.) remarkable variations in density, refractive index, and knock rating were obtained. For instance, a series of fractions boiling a t 115.5-116.1° C. (240-241' F.) showed densities varying from 0.733 to 0.727, indices of refraction from 1.4086 to 1.4065, and knock ratings from 4.8 to 16.5. Unexpected periodic relations were found between the properties tested. I n general, the fractions having the lowest densities and refractive indices had the highest knock ratings, and vice versa. The data for typical points on the curves for the properties of the fractions measured are given in the table. The points selected are those a t which any one of the three properties, density, index of refraction, and knock rating, show a maximum or a minimum. A minus sign after a value in the table indicates a minimum for that particular property and a plus sign indicates a maximum. It will be noted that, of the seventeen points fixed by the presence of either a maximum or a minimum in one of the three properties measured, six correspond to maximum values for the density and index of refraction and minimum values for the knock rating, while four correspond to minimum values for the density and index of refraction and maximum values for the knock rating.
German Coal Works Abandon Ammonia Synthesis Plan According to information received at the Department of Commerce, the Gelsenkirchener Bergwerks, A. G., Ruhr coal operators, have abandoned their plans to erect a direct synthetic ammonia plant with a 30,000-ton nitrogen capacity, apparently because of lack of sufficient coke-oven gas from its coke plant at the "Monopol" pits.
