Document 0gkZ8N2gGxdqGdLL3O7B3qoRR

December, 1926 INDUSTRIAL AND ENGINEERING CHEMISTRY 1235. water is merely a confirmatory test, a high solubility indicat ing high alcohol content, although the presence of ethyl lactate increases the solubility in water. There would be no difficulty, however, in distinguishing between alcohol and ethyl lactate by examination of the boiling range curve. Solubility in three volumes of saturated sodium chloride solution gives an indication of the amount of methanol, ethyl alcohol, and acetone present. Correlation and Evaluation of Results The correlation of the results of the various tests is by no means easy. The greatest help is a fund of experience gained by working with solvents in various mixtures. The boiling range indicates which of the various solvents may be expected and in combination with the saponification value one can estimate quite accurately what materials are present and how much of each. Exact figures for the composition of a lacquer cannot be expected to result from the usual examination such as here outlined. For instance, no known method will distinguish between butyl acetate and amyl acetate with the accuracy that we can distinguish between butyl acetate and butyl alcohol. For this reason the composition of a lacquer as the result of an analysis can best be expressed as varying within certain limits. The total hydroxyl group can be ascertained by acetylization, but the method is useless as a means of determining whether the actual constituents are monatomic alcohols or hydroxy esters such as ethyl lactate. Here again the boiling range curve will help in making 'correct deductions. Special Tests Special analytical procedures can be applied in the caseof certain solvents, which serve as definite measures of theamounts of these various constituents. For example: Me t h a n o l --Chapin-Elvove test, or the prussic acid method Al k y l Ca r b o n at e s --Determination of the carbonate formed: by saponification Al k y l La c t a t e --Oxidation with permanganate and deter mination of the acetaldehyde formed Al k y l Ox a l a t e s --Saponification and determination of oxalate radical a c e t o n e--Messenger or hydroxylamine method Or g a n ic Ac id s --It sometimes becomes necessary Jto de termine what organic acids are present in combination. The best method of carrying out such an investigation lies in the use of the Duclaux distillation scheme. A dilute aqueous solution of the free organic acids is distilled under definiteconditions. As was shown by Duclaux, each volatile fatty acid distils from an aqueous solution at a definite rate, re gardless of the presence of other similar acids, and in this way it is possible to determine what organic acids are present. The method is of value only in the hands of an analyst thoroughly experienced in the technic of the procedure. Some Effects of Ultra-Violet Light on Paint Vehicles1 By George F. A. Stutz Th b Nb w Je r s e y Zin c Co ., Pa l mek t o n . Pa . HE effectiveness of blue and ultra-violet light in ac T celerating the drying of an oil film is generally recog nized.2 The effect of such light in accelerating the stirred continuously with a small glass stirrer, and a slow stream of air, oxygen, or nitrogen bubbled into the oil. The temperature stayed nearly constant, at about 50 C. The destruction of the film is also well established.3 The preseonilt was sampled at intervals until it had attained a consider paper reports some results obtained in an investigation of the able body. The viscosity of the several samples was deter mechanism of this accelerating action displayed by ultra mined by use of the Gardner-Holt tubes and, in the case of the violet light. It seems probable that the decomposition, samples beyond the range of the tubes, the result was ob or "weathering," of an oil film is simply a continuation of the tained by timing the rise of the air bubble in the tube and drying of the film, and hence the same reaction or series of assuming the rate of rise to be inversely proportional to the reactions must be involved in both. viscosity.4 Method The molecular weights were very kindly determined by J. S. Long, of Lehigh University, using the freezing point method.3 The effect of ultra-violet light on a mass of wet oil has been As a further means of studying the action of ultra-violet studied by placing about 300 cc. of oil in a 400-cc. flask of light and the changes it accelerates, the degree to which such light is absorbed by the oil was measured. This absorption was determined in the wave-length interval from 3655 A. to 2300 A., using an ultra-violet spectrophotometer. A diagram of the apparatus, as used, is shown in Figure 1. Light from the quartz Uviarc lamp passes through the quartz cell containing a thin film of oil and is dispersed in the Bausch & Lomb quartz monochromator. In order to measure visually the intensity of the ultra-violet light transmitted, A. H. Pfund suggested the use of a thin screen of fluorescent uranium glass cemented to a clear glass prism. The screen is viewed from above at an angle of 60 degrees or more, the lens clear fused quartz, and exposing it to a Cooper-Hewitt quartz L rendering parallel the light from the foreshortened image Uviarc at a distance of 30 cm. (12 inches). The oil was of the slit. When so viewed the fluorescent light is particu i Presented before the Midwest Regional Meeting and the Meeting of larly brilliant, and is easily photometered by means of the. the Section of Paint and Varnish Chemistry of the American Chemical Macbeth illuminometer. The intensity of the fluorescent Society, Madison, Wia., May 27 to 29, 1928. * Gardner, Paint Mfrs. Assoc U. S>, Tech. Circ. 172. * Nelson, Proc. Am. Soc. Testing Materials, 22, Pt 11,485 (1922); Nelson and Schmutz,. Ibid., Pt. II, 920 (1924). light is proportional to the intensity of the radiation falling Barr. Phil. Mag., 1. 385 (1926). Long and Smull, Th is Jo u r n a l , 17, 138 (1925). 1236 INDUSTRIAL AND ENGINEERING CHEMISTRY Yol. 18, No. 12 Curve 3--Change In Absorption Shown by Raw Linseed OU after Exposure to Ultra-Violet Light in Presence of Nitrogen upon the fluorescent screen, and hence a direct measure of the light transmitted by the oil film is obtained. By so viewing the fluorescent screen at an angle, no difficulty is experienced from "impure radiation" in the monochromator, since such "impure radiation" is due chiefly to longer wave lengths, not affecting the fluorescent screen. The quarts cell, containing the oil, consists of two quartz Curve 4--Change in Absorption Shown by Raw Perilla Oil after Exposure to Ultra-Violet Light in Presence of Oxygen plates, separated at one end by a thin strip of tinfoil. The angle of the wedge so formed, and hence the thickness of any portion of it, is found by measuring the set of interference fringes obtained on reflecting monochromatic light from the two surfaces of the wedge. The transmission of several different thicknesses of each oil sample was measured to give check values. The degree of absorption shown by the oil is December, 1026 INDUSTRIAL AND ENGINEERING CHEMISTRY 1237 best expressed in terms of the absorption coefficient K calculated from the relationship I = It, 10-** where I -- intensity of transmitted light - Jo = intensity of incident light. I = film thickness in centimeters Results * The degree of absorption shown by several commercial samples of treated and bodied linseed oils is recorded in Curve 8. Similar results for a series of samples taken at intervals during an air-blow of linseed oil are shown in Curve 9; Curve 10 records the absorption of several oil fatty acids, and of the monoglyceride of linolenic acid.6 Discussion The changes in the physical and chemical constants of the oils after exposure to ultra-violet light are recorded in Table I. The degree of absorption of ultra-violet light by the several samples before and after exposure is shown in the series of curves, 1 to 7, in which the absorption coefficient K is plotted against the wave longtll. Examination of the data in Table I shows that the effect f exposure of wet oils to ultrarviolet light is similar to the effect of heat and sir-blowing. Increases in viscosity, molecu- lar weight, and. refractive index are accompanied by a de crease in the iodine number. The acid number also increases . The ^ is indebted to j. s. Long {ot ^ of acids and for the linolenic monoglyceride. 1238 INDUSTRIAL AND ENGINEERING CHEMISTRY Vol. 18, No. 12 Wane -length of Light - in A.U. Curve 10--Absorption Shown by Acids Contained in Linseed Oil and Monqglyceride of Linolenic Acid steadily with increasing exposure to light. It must be re membered that the temperature of the oil remains at about 50 C, and, therefore, very little acid can be volatilized. The light has the additional effect of bleaching the oil until nearly colorless. The increase in the absorption of ultra-violet light, with increase in molecular weight and body, is of interest. Ac cording to Draper's law, only the light absorbed is capable of causing photochemical action. The longer the oil is ex posed to light, the more absorbing it becomes, and hence the greater is the effect of the light. The effect is cumulative. It is noticeable that with increasing molecular weight and body the absorption curve does not change its general shape, hut is simply raised. The indication is that the material or materials causing this characteristic absorption of ultra violet light are present in the original sample, and bodying the oil simply causes an increase in the concentration of such materials. Such increase cannot be due to an increase in acid content, since the pure acids themselves have a less absorption, usually, than the oil samples containing only 4 or 5 per cent of such acids. ' This study of the absorption of ultra-violet light by paint vehicles is being extended to dry films. Acknowledgment ! The author wishes to acknowledge the assistance and crit icisms of the members of the Research Division of the New Jersey Zinc Company, the help rendered by J. S. Long, and the assistance of C. Hall in making the observations. Table I--Changes in Physical and Chemical Constants of Oils after Exposure to Ultra-Violet Light Exposure to U. V. Gas light hours present Viscosity poises Refractive index at Mol. wt. 26 C. Iodine No. Acid (Hanus) No. Raw Linseed Oil .0 o;4 773 1.4751 175 3.4 12 Air 0.75 910 1.4775 171 4.5 24 Air 12.5 1290 1.4779 117 7.4 30 Air 118.0 1785 1.4832 106 8.5 3 Oxygen 0.6 969 1.4753 6 Oxygen 2.25 1551 1.4786 9 Oxygen 22.0 1858 1.4815 169 3.7 127 7.0 113 9.4 9 27 . 36 0 3 6.5 9.5 0 4 8 12 0 8 8 0 18 36 54.5 Nitrogen Nitrogen Nitrogen Oxygen Oxygen Oxygen Oxygen Oxygen Oxygen Oxygen Oxygen Oxygen Oxygen Oxygen 0.55 2.85 5.25 788 -- 1220 Periila Oil 0.50 0.65 5.25 33.0 .762 844 1364 1930 Poppy-Seed Oil 0.55 1.1 4.60 5.25 Soy Bean Oil 1.0 2.0 5.7 Castor Oil 4.95 5.45 18.07 47.50 1.4760 1.4785 1.4803 1.4773 1.4780 1.4839 1.4851 1.4692 1.4711 1,4747 1.4750 1.4706 1.4730 1.4750 1.4729 1.4738 1.4749 1.4759 . 160 149 113 181 154 . 143 116 123 123 105 87 119 114 113 81 70 -- 70 3.5 5.5 5.5 11.0 11.5 14.7 15.0 5.5 5.9 11.6 12.4 8.0 9.5 8.5 1.1 2.3 11.6 28.0 Manufacture of Carbon Black on Public Domain--The De partment of the Interior has granted to George B. Jenkinson, of Denver, Colo., oil and gas leases, on a royalty basis, on 2560 acres of land in Grand County, Utah, as a result of the discovery of gas adapted for the manufacture of carbon black. It is expected that a carbon black plant will soon be constructed on these leaseholds. The leases Were granted as the result of a discovery of gas peculiarly adapted for the manufacture of carbon black. The leases stipulate that the gas may be used for this purpose, pro vided modern and improved methods are employed, and further that if, after ten years, the Secretary of the Interior finds a de mand for the gas for domestic or industrial purposes, the lessee shall he required to supply the gas to gas-line connections. The leases also provide that where the gasoline content is more than one-half gallon per 1000 cubic feet, the gasoline shall be extracted and a royalty paid to the Government on all gaso line produced.