Dec.,
1920
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
T h e potassium chloride was not tested for purity but was assumed t o be pure (theoretical KzO, 63.17 per cent). Whether i t was pure or not does not matter so much, as aliquots from t h e same stock solution were used .;n all of t h e above tests. T h e results indicate t h a t the presence of sodium chloride or sodium sulfate causes low results when using 80 per cent alcohol, and t h a t when using 92 per cent alcohol the results are practically the same whether t h e sodium salts are present or not. Furthermore, the fact t h a t results are practically t h e same with or without the sodium salts when washing first t o remove t h e excess platinic chloride, then with LindoGladding solution t o remove sodium salts, and finally with 80 per cent alcohol, tends t o prove our theory t h a t the solution of sodium chloride or sulfate in 80 per cent alcohol does have a greater solvent action on t h e potassium platinic chloride t h a n the 80 per cent alcohol alone. As further proof another series of experiments was made. Pure potassium platinic chloride was prepared by evaporating the leachings from the crucibles in t h e above tests, washing thoroughly with 80 per cent alcohol, Lindo-Gladding solution, and finally with 80 per cent alcohol, and drying in an oven a t 130’ C. Four grams were dissolved a n d diluted t o 500 cc., a n d aliquots of z j cc. (equal t o 0.20oo g.) were taken; a few drops of hydrochloric acid a n d of platinic chloride were added, together with sodium chloride and sodium sulfate as shown in Table 11, a n d rxaporated t o paste as in regular potash determination. The washing was precisely t h e same as in t h e foregoing tests, except t h a t g j per cent alcohol replaced t h e 92 per cent alcohol used in t h e previous tests. Also, denatured alcohol, Formula 30, was used. The results shown in Table 11, giving grams of KyPtC16 found, are in every case the average of two or three determinations. TABLEI1 80 Per cent Alcohol Grams KzPtCle alone. . . . . . . . . . 0.1999 0.1 g. NaCl added.. , 0.1992 0.2 P. NaCl added. 0.1978 0.4 3. NaCl added.. 0.1960 0.1 g. NatSOa added.. 0.2011 0 . 2 g. NatSOr added. 0.1988 0 . 4 g. NazSO4 added. . . . .. 0.1985 0.05 g. NaCl 0.05 g. NatSOa added., . 0.1995 0.1 g . NaCl 0.1 g . NazS04 added.. , 0.1983 0.2 g. NaCl 0.2 g. NazSO4 added.. . 0.1957
. . . .. ..... .. .. .. .... . . . . . .. .. +. . . . . . . +. . . . . .. +. . . . . . .
95 Per cent Alcohol Grams 0,2009 0.2017 0.2025 0,2002 0.2012 0.2020 0,2009
95 Per cent Alcohol First. 80 Percent‘ Alcohol Last Grams 0.2018 0.2007 0.2005 0.2002 0.2013 0.2009 0.2007
0.2011
0.1999
0,2006
0.2009
0.2004
0.2012
I n these results t h e sodium chloride causes slightly lower results t h a n the sulfate. This condition is somewhat different from those in Table I, as in t h a t case the potassium salt also was converted t o sulfate, thus yielding some free sulfuric acid after evaporation, whereas in Table I1 no free sulfuric acid would be formed in a n y case. Otherwise these d a t a confirm those in t h e first table. No very complete study of t h e effect of various salts or t h e strength of the alcohol used in washing is covered by t h e results given above, but sufficient has been done t o warrant t h e further careful study
I 189
of this subject. The effect of other salts, such as those of calcium and magnesium, should be included. T h e d a t a do seem t o warrant the suggestion t h a t t h e official method be changed a t least t o allow the use of the strong alcohol, about 9 5 per cent, for t h e first washings t o remove excess platinic chloride, a n d the 80 per cent alcohol for final washing, if this is considered necessary; then if there is anything present which 80 per cent alcohol should remove a n d which 9 j per cent alcohol will not remove, i t can be done in t h e final washing without including the effect of sodium or other salts. Unfortunately all analysts have not followed t h e official method in t h e use of 80 per cent alcohol. This includes some works laboratories as well as referees. Some use strong alcohol altogether, some Columbian spirits (about 96 per cent), while others have faithfully followed t h e official method in using 80 per cent alcohol as prescribed, thereby finding lower percentages of potash. While the results obtained by using stronger alcohol are nearer t h e t r u e values, as judged from the foregoing a t least, t h e fact remains t h a t the official method specifies 80 per cent alcohol, and all laboratories making this determination should be governed accordingly until t h e method is changed. Fertilizer chemists have been aware for some time t h a t the results obtained on analyses of mixed fertilizers, even on carefully prepared laboratory samples, are lower t h a n the results calculated from t h e analyses of the potash salts used. This has been largely attributed either t o the formation of some insoluble potassium silicate or t o the selective absorption of t h e calcium oxalate or phosphate precipitate for salts of potassium. How much is really due t o either of these causes, and how much t o t h e strength of t h e alcohol, is unknown, as 80 per cent alcohol has been used when making study of this problem. Our own results have usually indicated a loss of from 2 per cent t o 3 per cent of the potash as calculated, and this is no small item t o t h e fertilizer.manufacturer, who deserves credit for all of the potash added. THE DETECTION OF OILS OTHER THAN LINSEED I N PAINTS BY MEANS OF THE HEXABROMIDE NUMBER OF THE FATTY ACIDS’ By Herbert Bailey and Walter D. Baldsiefen EXPERIMENTAL STATION, E. I. DU PONT DE NEafOURS 82 CO., HENRYCLAY,DELAWARE
T h e abnormally high price of linseed oil during t h e last two years has naturally increased interest i n methods for detecting adulteration of this basic paint material. Messrs. Steele and Washburn2 in ‘their recent article on “A New Hexabromide Method for Linseed Oil” have most ably covered t h e more important work on hexabromide methods. In using the modification of Eibner’s method3 proposed by Steele and Washburn, which was submitted for cooperative work t o members of Committee D-I of the 1 Presented in part before the Division of Agricultural and Food Chemistry at the 59th Meeting of the American Chemical Society, St. Louis, Mo., April 12 to 16, 1920. 2 THIS JOURNAL, 12 (1920), 52. 3 Farben-Ztg., Nov. 23, 1912 (No. 8).
I 190
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
A. S. T. M., the authors have felt t h a t there was room for further simplification in t h e procedure. I n t h e hope t h a t under properly controlled conditions i t would be possible t o get concordant results without separating the fatty acids, i. e . , by brominating t h e glycerides, t h e procedure adopted by Bailey and Johnson in their work on salmon oil1 was studied. A fairly complete investigation has proved, however, t h a t it is necessary t o add t h e bromine t o t h e f a t t y acids in order t o get results of any value in detecting t h e presence of foreign oils in linseed. I n our method, therefore, we have adopted a procedure similar t o t h a t recommended by Steele and Washburn for t h e preparation of t h e fatty acids. As a solvent for t h e fatty acids we very much prefer ether t o chloroform, as in the latter t h e hexabromides are quite soluble, and t h e chloroform must therefore be completely removed before they can be precipitated. Work of previous investigators, especially Sutcliffe,z has pretty conclusively demonstrated t h a t under properly controlled conditions t h e hexabromides of t h e unsaturated f a t t y acids can be quantitatively separated from ether solutions. Another advantage which will appeal t o the works chemist is t h a t when ether is used it is unnecessary to- prepare a special chloroform as in the Steele-Washburn method, and a slight excess of bromine does not affect t h e final results, so t h a t it is not necessary t o use amylene or other reagents t o neutralize t h e excess added in the brominating process. I t is essential, however, t h a t an ether saturated with linseed oil hexabromides be employed, as they have a siight though appreciable solubility even a t o o C. B R 0 M I K A T 1N G R E A G E NT
Bailey and Johnson found i t much more convenient t o add the bromine in acetic acid solution t h a n as t h e pure element. Gemmell,3in his review of t h e work of earlier investigators on t h e insoluble bromine value of oils, pointed out t h a t t h e amount of acetic acid present materially affects t h e weight of bromides obtained. Presumably there is some optimum mixture of ether and acetic acid which will be most satisfactory as t h e bromination solvent. Freyer and Weston4 recommended 2 cc. of glacial acetic acid and 2 0 cc. of anhydrous ether. We found t h a t when 2 0 cc. of ether and 4 cc. of acetic acid were used in a determination, our pure linseed oil gave hexabromide values of 42.8 and 44.4,while with 2 j cc. of ether and the same amount of acid t h e results were 43.9 and 44.3. This indicated t h a t not only more concordant results but also slightly higher values were obtained when t h e percentage of ether in the mixture was increased. As I g. of linseed oil f a t t y acids requires about 0.5 cc. of bromine t o saturate them, and 3 0 cc. is a convenient volume in which t o carry out t h e bromination, a 2 0 per cent (by volume) glacial acetic acid solution of bromine has been adopted as t h e brominating reagent, and z j cc. of ether plus z cc. of acetic acid as t h e solvent in which t o dissolve t h e f a t t y acids. This gives in t h e THISJOURNAL, 10 (1918),999. The Analyst, 89 (1914), 28. 3 I b i d . , S9 (1914), 297. 4 “Technical Handbook of Oils, Fats 2 (1918), 1 1 1 . 1
2
and
Waxe:,”
Cambridge,
Vol.
12,
No.
12
final solution of fatty acids, bromides, ether, a n d acetic acid, approximately 13 per cent of t h e acetic acid, or practically t h e same as recommended by Freyer and Weston. BROMINATION PROCEDURE
BROXINATIOS-In this work t h e temperature of t h e ether solution of f a t t y acid has been kept about -1o0 C. by immersion in a small bath of chopped ice and hydrochloric acid. I n a series of determinations on two samples of mixed fatty acids two brominations of each were made a t o o C. and two at -1o0 C. Those a t o o C. gave values for Sample A of 35.1 and 37.9, and for E of 3j.7 and 36.6, a variation in t h e first two of 2.8 and in t h e second 0.9. At -10’ C. t h e hexabromide values were 36.3, 37.5 and 37.2, 37.6, respectively, showing a discrepancy of 1.2 on Sample A and only 0.4 on E. While the d a t a obtained were too meager t o warrant any very definite statement with reference t o t h e effect of temperature on t h e bromination, ‘they were sufficient t o convince us t h a t it is safer t o work a t -10’ C. t h a n at o o C. E F F E C T O F R A T E O F BROMINATIOX-Many previous investigators have mentioned t h e importance of allowing sufficient time after t h e addition of the bromine t o t h e fatty acids for complete precipitation of t h e hexabromides, b u t little attention has been paid t o t h e rate a t which t h e brominating reagent is added. Although Bailey and Johnson had confirmed t h e statement of Sutcliffe t h a t t h e best results were obtained by allowing t h e brominated mixture t o stand over night, we made one series of determinations in which this point was investigated. It was found t h a t t h e same fatty acids precipitated in t h e same way gave values of 39.7 if filtered and washed after standing 3 hrs., 40.7 after 6 hrs., and 43.0 when allowed t o stand over night (16 hrs.) in t h e ice box. Apparently there is a continued increase in the formation of ether-insoluble bromides with increased time of standing, b u t this we believe is not due t o t h e substitution of bromine in t h e chain, as only a trace of free hydrobromic acid could be detected even in t h e solution which had stood over night. Experiments in which t h e same linseed oil acids were treated with t h e same amount of t h e acetic acid solution of bromine under identical conditions, with t h e exception of the rate at which t h e bromine reagent was added, proved t h a t this has some effect upon t h e yield of brominated products. Using 4 cc. of t h e reagent, a rather large excess, in each case, when t h e addition took place in 3 min., t h e hexabromide value found was 43.9,in I O min. 46.9, and in 30 min. 48.2. Another sample of f a t t y acids was treated with 2.7 cc. of the bromine reagent (which was just sufficient t o give a slight excess of bromine as shown by t h e permanent yellow color), and t h e rate of addition had much less effect on t h e final results. Pouring in t h e entire 2 . 7 cc. of -solution all a t once, we obtained 43.1 and 43.2 as t h e hexabromide values, a n d w h e n t h e reagent was dropped in slowly from a buret during t h e course of I O min., t h e values were 44.8 and 44.9. I n both sets of experiments t h e brominated solutions EFFECT O F TEMPERATURE O F
’
Dec., 1920
T H E JOURNAL OF IXDGSTRIAL AND ENGINEERING CHEMISTRY
were allowed t o stand over night in t h e ice chest before filtering and washing: DETAILED DESCRIPTION
O F METHOD
RE'iGENTS-The following reagents in about t h e quantities mentioned will be required for making ten determinations: Sodium Hydroxide Solution (1.4sp. gr.)-Dissolve 75 g. of C. P. KaOH in water and make up t o 2 0 0 cc. A2cohol (95 per cent by volume)--aoo cc. (denatured alcohol is satisfactory). Hydrochloric Acid-C. P., concentrated, 300 cc. cc. This acid should not Glacial Acetic Acid-ao show any reduction in t h e usual bichromate or permanganate tests. Glacial Acetic Acid Solutio.rz of Bromiize-30 cc. Five cc. of bromine z j cc. of acetic acid. T h e bromine must be free ,from non-volatile matter. Ether Saturated at o Q C. with Linseed Oil Hexabromides -Wash in a separatory funnel a liter of laboratory ethyl ether with four successive 100-cc. portions of distilled water (ice-cold) and dry with fused calcium chloride over night. I n t h e morning, pour t h e ether off through a folded filter paper into a 1.5- or a-liter flask. Add several thin slices of sodium, reflux until there is no longer any evidence of t h e liberation of hydrogen, then distil o f f the dry ether. Before t h e ether can be used i t must be saturated at o 0 C. with t h e hexabromides of linseed oil fatty acids t o prevent its dissolving hexabromides during t h e washing of t h e bromination products in the determination. T o prepare t h e hexabromides for this purpose, t h e directions given below have been found very satisfactory : I n a centrifuge tube dissolve about 5 g. of the f a t t y acids in 2 5 cc. of ether. Place t h e t u b e in a freezing mixture and a d d slowly, with shaking, bromine solution, until a red color is permanent. Let stand for a t least I j min., whirl t h e t u b e in a centrifuge until t h e precipitate has settled, and then pour off t h e ether. R u b up t h e precipitate with 2 0 cc. of cold absolute ether, whirl in a centrifuge, and pour off t h e wash ether. Repeat t h e washing with three more 20-cc. portions of ether. d f t e r drying, t h e hexabromide so obtained is pure enough for t h e preparation of t h e wash ether. To saturate t h e dry ether with t h e hexabromides thus prepared or those from previous determinations made of pure linseed oils, which should always be saved, add a t least 3 g. of t h e finely powdered substance and allow t h e solution t o stand a t room temperature with frequent shaking for several hours. Cool in ice water for 2 hrs., shaking from time t o time, and finally filter as rapidly as possible into a dry corkstoppered bottle. APPARATUS-In addition t o t h e ordinary equipment of a chemical laboratory, it is essential for t h e proper handling of this method t h a t one have t h e following apparatus: (a) Twelve centrifuge tubes about I X 5 in., of wellannealed heavy glass. ( b ) A laboratory centrifuge with cups for holding t h e above centrifuge tubes,
+
1191
DETERMINATION. Preparation of the F a t t y Acids -To j o cc. of oil in a 2-liter, round-bottom flask, add 40 cc. of XaOH solution (sp. gr. 1.4= 36. j o per cent YaOH) and 40 cc. of alcohol. Close t h e flask with a a-hole rubber stopper, carrying a quarter-inch tube, t h e lower end of which is just above t h e surface of t h e liquid, and heat on t h e steam bath for about 0.5 hr. Add a liter of hot distilled water and boil the soap solution until t h e alcohol is removed, passing a stream of COz continually through t h e inlet tube. If a free flame is used, about 0 . j hr. boiling -will be sufficient, but in this case it may be necessary t o insert capillary tubes t o prevent bumping of the liquid. If the solution is heated on the steam bath, 2 t o 3 hrs. are usually required. After removing the alcohol, cool slightly, acidify with dilute HC1 ( I : I ) , and warm until the fatty acids form a clear layer (continuing t o pass COz through the system all t h e time). Transfer t h e fatty acids and part of t h e solution t o a 500-cc. separatory funnel, allow t o stand a few minutes until the f a t t y acids collect on t o p of t h e aqueous portion, and draw this off. Pour the remainder of the mixture from the flask into the funnel, and run off t h e aqueous portion. Add 300 cc. of hot water, shake vigorously, allow the fatty acids t o separate, and again draw off t h e aqueous portion. Repeat this process until t h e wash water is neutral t o methyl orange, three washings usually being sufficient. R u n t h e warm f a t t y acids a t once into a centrifuge tube and whirl for about a minute t o separate the remaining water, then filter through a folded filter paper into a small bottle. When the major portion of t h e acids have run through t h e filter, discard t h e remainder and stopper the bottle with a tight cork. It is obvious t h a t the acids must be hot enough when poured on t h e filter t o remain completely liquid until filtered, as otherwise some of those with a high melting point may separate. Precipitatio?$ of the Hexabromides-Weigh accurately one of t h e centrifuge tubes, pipet into it as nearly as practicable 1.00g. of t h e prepared f a t t y acids and again weigh. For transferring t h e fatty acid, a piece of j mm. glass tubing about 2 0 cm. long, drawn out t o a tip and bent down a t t h e lower end and up a t t h e other in a shape similar t o a "S" wrench, is convenient. T o t h e fatty acids in the centrifuge t u b e add z j cc. of t h e ether saturated with hexabromides and 2 cc. of glacial acetic acid. Cool t h e tube and its contents t o about -10' C. by immersion in a bath of chopped ice t o which a little commercial hydrochloric acid has been added; then, keeping t h e tube in the cooling mixture, add from a buret t h e bromine reagent a t the rate of one or two drops per second, shaking t h e tube after each addition. Continue t h e bromination until t h e solution of fatty acids becomes permanently orange in color (usually for pure linseed oil this requires about 2 . 5 cc.), then remove t h e tube from t h e bath, stopper it with a cork, and allow t o stand over night in a n ice box. Washing and Weighing of the Hexabromides-Next morning cool t h e tube by immersion in a bath of cracked ice and rub up t h e precipitate by means of a weighed glass rod, being sure t o loosen any material
1192
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
adhering t o the side’of t h e tube. Whirl the tube in a centrifuge till the precipitate forms a hard cake on t h e bottom, cool in the ice bath, and decant t h e ether. Add 2 0 cc. of the wash ether previously cooled t o o o C. and rub up the precipitate with the glass rod. Return the tube t o the ice bath and when cool remove and whirl again in the centrifuge. Cool once more and then remove the ether by decantation. Repeat this ‘washing twice more, and after the last washing incline the tube and carefully t a p i t t o spread the hexabromide precipitate part way up the sides. Warm t h e tube in water a t 60” C. until most of the ether has evaporated, then attach it for 1 5 min. t o a vacuum line showing a pressure of 30 t o 40 mm., keeping the temperature around 60’ C. Wipe the tube dry and allow i t t o , stand in the balance a t least 1 5 min. before weighing. T o t h e weight of the precipitate in the tube add the weight of the slight amount adhering t o the glass rod. This total weight of precipitate, multiplied by IOO and divided by the weight of t h e fatty acids taken, gives t h e hexabromide percentage.
Vol.
12,
No.
12
o n the hexabromide value of the various treatments t o which linseed oils are subjected in the preparation of commercial products, such as varnish and lithographic oils, we analyzed a number of samples representative of these classes. The results are shown in Table 11. TABLBII- -IODINE AND HBXABROMIDE VALUESOB TRBATED LINSBEDOILS Sample Iodine Hexahromide Number Material Number Number 64 1 Linseed No. 553 f 5 % Japan Drier1 166.8 41.1 42.6 642 Linseed No. 553 4- 10% Japan Drier 161.5 41.0 40.9 643 Linseed No. 553 f 20% Japan Drier 152.5 39.2 39.0 Linseed No. 553 f 5% C.W.O. Driera 164.8 40.8 644 39.2 10% C.W.O. Drier 158.9 39.9 Linseed No. 553 645 40.3 Linseed No. 553 f 20% C.W.O. Drier 147.4 39.9 646 39.4 561 Commercial Boiled Linseed 173.8 42.6 41.9 359 Heavy Bodied Linseed (Held at 560’ F. 80.8 10.0 for 5 hrs.) 12370 refined linseed oil, 5% litharge! 1 % MnOz, 71% turpentine substitute. * 13% C:W.O.,8% rosin, 10% linseed oil, 5 % lead manganese salts, 64% turpentine substitute.
+
+
The Japan drier used in Samples 641 t o 643 was really a mixing varnish and very evidently did not have any RESULTS OBTAINED O N P U R E L I N S E E D AND OTHER OILS appreciable influence on t h e linseed oil with which i t PURE LINSEED oms-Unfortunately only a very was mixed, other t h a n mere dilution. Even after few samples of pure linseed oil were available for this standing for three months these oils had not changed work, but these were analyzed, with the results appreciably in their hexabromide values. Samples given in Table I. 644 t o 646, which contained t h e China wood oil drier, TABLEI-IODINE AND HEXABROMIDB VALUES OR PURB LINSEED OILS were similarly unaffected, although their iodine numSample Numher ........ 535 553 563 564 648 801 813 182.5 Iodine No. (Hanus) ..... 189.8 176.2 185.4 176.5 177.7 bers were reduced more t h a n in t h e case of t h e first Hexabromide Value ..... 44.1 4 2 . 6 42.1 42.3 4 3 . 0 i i : 1 4 2 . 9 44.0 41.9 42.0 4 3 . 0 42.7 41.1 4 2 . 6 series. .. .. .. .. .. .. .. .. .. .. .. .. 44 33 .. 25 .. .. .. .. .. .. So far we have had time t o test only one true boiled .. .. .. .. .. .. .. .. .. .. .. .. 44 23 .. 63 .. .. .. .. .. .. oil, t h a t is, a linseed oil t o which had been added a small No. 535-Oil extracted in laboratory from Argentine seed amount of lead and manganese in t h e form of their No. 553-Oil extracted with aasoline on commercial scale from North Ameiican seed f a t t y acid soaps by heating t h e mixture a t 250’ F. No. 563-Commercial raw oil N o . 564-Commercial acid refiqed oil until homogeneous. I n this instance, Sample 561, No. 648-Pure raw oil (authentic A.S.T.M. sample) neither t h e iodine nor hexabromide value differed from No 801-Oil extracted in lahoratory from Argentine seed No. 813-Commercial raw oil t h a t for a pure raw oil. T h a t t h e oxidation which The figures in Table I are of interest, because they takes place in bodying an oil very materially affects demonstrate, t o a limited extent, i t is true, t h e value both t h e iodine and hexabromide values, as would be of the hexabromide number as a basis for judging the expected, is indicated by t h e results on Sample 359. purity of linseed oil. The iodine values of the oils The best commercial practice for the production of examined vary from 176 t o 189, 13 points, while the “boiled oil” does not involve any appreciable heating, maximum difference in the hexabromide values is 3, as the metallic driers are nowadays usually f a t t y from 41.1 t o 44.1. This narrow spread in these so- acid soaps, and, therefore, readily soluble in t h e oil. called “constants” is, of itself, perhaps insufficient t o The older method for making boiled oils, which neceswarrant the substitution of the more difficultly ob- sitated prolonged heating of t h e raw oil above 400° tained hexabromide value for the now almost uni- F. with an oxide or other inorganic salt of the metal, versally accepted iodine value, but when considered often caused not only a darkening of the oil, but a n with t h e values of these same constants for the oils appreciable lowering of its iodine value. Where this commonly used t o adulterate linseed oil i t is of great older process is used, we have found t h a t there is a importance. Discussion of this point will be taken decrease in the hexabromide value along with t h e u p after Tables I1 and 111, which give our results on iodine value. treated linseed oils, soy-bean, fish and tung oils, have There , i s some indication t h a t t h e changes taking been considered. T h a t t h e method which has been place in linseed oil during oxidation with air a t high proposed for determining the hexabromide value is temperatures (400’ F.) do not affect the hexabromide capable of giving results agreeing among themselves value and iodine value t o t h e same extent. Some within about 2 per cent, is evidenced by the figures preliminary work makes i t appear possible t h a t , by determining both of these constants and getting the obtained on Sample 648. TREATED LINSEED oILs-It is one thing t o detect relation between them, a factor may be found which adulteration of pure raw linseed oils and quite another will make practicable t h e differentiation between pure t o determine the purity of “boiled,” “heavy bodied,” oxidized or heavy-bodied linseed oils and mixtures of or “bung-hole boiled” oils. T o ascertain t h e effect these with other oils.
Dec., 1920
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
O I L S OTHER T H A N P U R E LINSEED-The most COmmOn substitutes for linseed are soy bean, fish, and (in a sense) tung, although t h e last a t the present time is used t o supplement rather t h a n replace linseed. I n Table I11 will be found t h e hexabromide values of a few samples of these oils and mixtures of soy-bean and linseed oils. TABLE111-IODINE Sample Number 310 658 659
660 661 812 649
HEXABROMIDE VALUES OF OILS OTHER THAN PURELINSEED Iodine Hexabromide Material Number Number Commercial Raw Soy-bean Oil 133.2 4.2 4.9 Authentic Raw Soy-bean Oil .* 7.3 7.5 Authentic Raw Soy-bean Oil 5.7 5.5 Authentic Raw Soy-bean Oil 4.4 4.3 Authentic Raw Soy-bean Oil 4.3 4.3 Commercial Raw Soy-bean Oil 135.5 7.2 85% Linseed 15% Soy-bean Oil 171.9 37.7 AND
. ... ...
...
650
+ 75% Linseed + 25% Soy-bean Oil
168.0
651
65% Linseed
+ 35% Soy-bean Oil
164.2
652
50% Linseed
+ 50% Soy-bean Oil
622 623
Pure T u n g Oil Menhaden Oil
... ... ...
37.8 34.2 33.8 31.4 30.9 23.3 24.3 00.0 35.9 36.2
By our method, the hexabromide value of pure soybean oil averages about 6.0, varying from 4.2 t o 7.5, tung oil gives no ether-insoluble bromine derivatives, and fish oils yield octobromides which are insoluble in warm chloroform, and, therefore, readily distinguishable from t h e hexabromides. The melting point of the linseed hexabromides is about 180' C., while the fish-oil octobromides decompose a t 2 0 0 ' C. without melting. I t is well, therefore, t o test t h e bromides after t h e final weighing by warming them gently. If they blacken, indicating t h e presence of fish oil octotromides, they may then be treated with h o t chloroform which will dissolve all t h e hexabromides, leaving t h e insoluble octobromides which can be weighed, T h e details of this procedure have not been worked out, but anyone having occasion t o make the separation can undoubtedly develop a method with little difficulty. Q U A N T I T A T I V E APPLICATION OF T H E METHOD-using t h e figures given in Table I11 for Samples 649 t o 652, whicl! were of known composition, and t h e average hexabromide values of 42.0 and 6.0 for linseed and soy-bean oils, respectively, i t is interesting t o note the nearness with which t h e actual proportions of the two oils may be calculated. For Sample 649, taking the average value of 37.75, we get 88.2 per cent linseed and 11.8 per cent soy-bean oil, against 85 and 15 per cent actually present. Similarly for Sample 650, t h e proportions found are 77.7 per cent linseed and 22.3 per cent soy-bean, present 7 5 and 2 5 per cent; found for Sample 651, 69.8 per cent linseed and 30.2 per cent soy-bean, present 65 and 35 per cent; a n d in Sample 652, which contained equal parts of the two oils, we found 49.4 per cent linseed and 50.6 per cent soy-bean oil. K E X A B R O N I D E V A L U E OP OILS F R O M C O M M E R C I A L P A I N T S
The crucial test of t h e real value of the hexabromide method is in its application t o t h e analyses of com-
1193
mercial paints. We have shown t h a t the addition of substitutes t o linseed oils cannot only be detected with a fair degree of accuracy, but also quantitatively determined, and the next question is how far this method is reliable with ordinary paints. Work on this phase of t h e subject has been started, b u t much more is needed before definite conclusions can be drawn with reference t o the effect of various pigments, Japan driers, and other normal paint ingredients. I n Table I V are collected the results obtained on a few paste colors, and paints of known and unknown composition. TABLEIV-ANALYSES OF GASOLINEEXTRACTS OF PASTECOLORSAHD
PAINTS HexaUnsaponiSample bromide fiable Linseed Oil = 42 Soy-bean Oil = 6 Number Value Matter Calculated Present Calculated Present 761 37.7 0.96 88.0 12.0 762 29.2 0.38 64.4 35.6 ... 21.7 0.38 43.6 56.4 7 63 18.5 0.66 34.7 65.3 764 35.4 0.90 81.6 18.4 765 ... 766 41.41 5.38 98.3 1.7 ... 1.32 1.1 41.6 98.9 767 43.7 0.59 768 100.0 0.0 43.5 769 100.0 0.0 0.47 770 1.11 8.1 39.1 91.9 ... 41.81 99.4 0.6 ... 771 3.40 ... 772 3.0 ... 0.0 100.0 68.0 788 30.5 1.63 32.0 789 25.3 1.80 46.4 53.6 37.2 790 28.6 1.20 62.8 41.7 791 27.0 0.46 58.3 50.0 792 24.0' 3.11 50.0 ... 60.5 793 26.2 0.58 43.9 56.1 39, § 76.2 794 33.41 3.56 23.9 76.1 23.8 91.9 795 39.61 93.3 6.7 8.1 3.47 100.0 806 41.1 97.5 2.5 0.0 100.0 807 40.7 96.4 3.6 0.0 100.0 808 39.8 93.9 6.1 0.0 75.0 809 35.0 80.5 19.5 ... 25.0 75.0 810 33.5 76.4 23.6 25.0 81 1 34.8 80.0 75.0 20.0 25.0 36.0 83.3 16.7 815 88.9 11.1 816 38.0 ... 75.3 * 817 33.1 24.7 40.4 95.5 4.5 818 ... ... 40.0 5.6 819 . .. 94.4 ... 39.8 6.2 ... 93.8 820 100.0 43.3 82 1 ... 0.0 822 ... 23.4 48.3 51.7 39.9 823 94.1 5.9 1 Hexabromide value has been corrected for unsaponifiable in excess of 1.5 per cent.
...
... ... ... ... ... ... ... ...
... ... ...
... ... ... ... ... ... ... ... ... ... ... ... ... ...
... ... ... ... ...
... ...
... ...
... ...
... ..,
... ... . . e
... ... ... ... ... ... ...
The figures given in Columns 4 and 6 are calculated from t h e hexabromide values found, on the assumption t h a t t h e average linseed hexabromide value is 42, t h a t of soy bean 6, and t h a t of the unsaponifiable zero. The normal content of unsaponifiable matter in linseed oil is about 1.0per cent, and where not over 1.5 per cent was found in t h e fatty acids taken for analysis, we have assumed t h a t only saponifiable oils were present in t h e original paint, and, therefore, applied no correction in these cases. I n view of the limited amount of d a t a which has been collected on this part of our investigation, we are hardly warranted in drawing any more t h a n t h e general conclusion t h a t Samples 761 t o 765, 7 7 2 , 788 t o 795, and 809 t o 817, all of which have a corrected hexabromide value of 39 or less, undoubtedly contain oils other t h a n pure raw linseed. Some idea of the degree of accuracy with which t h e relative proportions of linseed and soy-bean oils c a n be determined by t h e proposed method may be obtained from the results on paint samples of known composition, reported in Table IV. These Samples 793 t o 811 were made in a small paint mill, and duplicate as nearly as possible commercial colors found on t h e market. The tabulated'results indicate t h a t i t is possible by the hexabromide value t o determine
