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IN DUSTR IA L AN D EN G I N E ER IN G CH E M ISTR Y
After 2.5 years of storage the materials which appeared to be most effective in retarding changes in gum spirits of turpentine were powdered calcium oxide and powdered magnesium. The turpentine stored in contact with these materials was water-white, had the sweet odor of fresh gum spirits, and showed no evidence of change. Bone char prevented the development of the sharp odor of oxidized turpentine, but the turpentine acquired a yellowish color. Some of the organic reducing agents also prevented a change in odor but discolored the turpentine. After 5 yearq of storage the turpentine to which no preservative had been added vias turbid, viscous, discolored, and had a sharp odor. It had a specific gravity of 0.905, an acid number of 5 . 5 , and the evaporation residue [from 10 cc. in a flat dish 3 inches (7.6 em.) in diameter] after three 1-hour periods of drying in an electric oven at 97" t o 100" C. was 12.8 per cent by weight. Turpentine stored with calcium oxide had the best color of any of the samples (almost waterwhite) and an odor almost like that of fresh gum spirits, but the specific gravity and evaporation residue were much higher than for fresh gum spirits, the specific gravity being 0.003 higher than allowed in A. S.T. M. specifications. The best preservatives, as indicated by specific grarity and evaporation residue, as well as odor, were acid sodium sulfite, hydroquinone, and pyrogal!ol. The last two produce dark colors in turpentine which would necessitate redistillation or limit the use of the turpentine to dark-colored products like shoe polish. The turpentine which had been stored for 5 years in contact with these materials had a specific gravity of 0.870 to 0.871 (within the A. S. T. 11.specification limits) and eraporation residue of 0.8 to 1.1 per cent. The turpentine stored with acid sodium sulfite was only slightly darker than standard and was very fragrant. I t did not give a test for sulfur by the copper strip test.
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Schiff ( 7 ) found that the characteristic pungent odor of American turpentine can be removed by treatment wibh acid sodium sulfite solution but soon returns on exposure of the turpentine to the air. From results of the present writers it appears that solid acid sodium sulfite not only removes the pungent odor of turpentine but is also effective in retarding the changes which ordinarily result from aging. .~CKSOWLEDGMEST
The authors wish to acknowledge the privilege accorded to the Bureau of Chemistry and Soils by the Gold Dust Corporation of studying the changes in turpentine during long-time commercial st'orage in tanks and drums, and particularly the assistance of E. T. Narceau of t,hat firm, to whom t'heg are indebted for all the samples taken during the period of storage. The conditions for large-scale tank storage were suggested by F. P. Veitch of the Bureau of Chemistry and Soils.
LITERATURECITED (1) Am. Soc. Testing Materials, Standards, Pt. 11, 11. 300. Sgecifications D13-26 (1930). ( 2 ) I3urnett and Salzberg, paper presented before 32nil Annual Meeting, . h i . Soc. Testing hIaterials, June 94 to 28, 1999, (3) Dupont and C'rouset. Bull. i'inrt. p i i ~ S , o . 58, 101-5 (1029!. (4) Kingzett anti Woodcock, J . SOC.('hem. I d . .29, T S 1 tlS10). ( 5 ) Moureu and Dufraisse. ('hemi.yti..ij & Imlu.~tru,47, 519 (1928) ; ( ' h e m . Rex.. 3. 113 (lWG!. (6) Schorger. J. ITD: EXG.(:HE.;',, 6, 541 (1914;. (7) Schriff, C'henL.-Zfg., 20, 361 (1898). (8) T'eitch and Grotlisch, U. S. Dept. . b r . , Bull. 898 i 1 0 9 1 l RECEIVEDApril 2 , 1934. Presented as part of t h e joint Byiiipiisiuiii u i i Kava1 Stores befor e the Divisions of .lgricultural and Food Cheniistry and of Industrial and Engineering Chemistry at t h e 37th Meetins of the Aiiierican Chemical Society, St. Petershurg, Fla., 1 I a r c h 25 t o 30, 1934.
Use of Rosin for Soap Manufacture .~RCHIBALD CAMPBELL, 3239
Stettinius 24ve., Cincinnati, Ohio
O S I S has been an important constituent of soaps in the United States for many years, and, although it has . been replaced to a considerable extent by other fats and oils, it is still extensively used in many grades of American household soaps.
PROPERTIES OF ROSIXSOAPS Common rosin a t temperatures below 60" F. is a hard, brittle, vitreous solid, while a t higher temperatures it becomes tacky, sticky, and somewhat plastic. The composition is variously given as abietic acid with some abietic anhydride and other rosin acids, and as a mixture of rosin acids. Gum rosin is prepared from the distillation of crude gum turpentine and wood rosin is obtained by extraction from pine tree stumps and waste pine wood by the use of solvents. Both types of rosin always contain 1-arying amounts of nonsaponifiable substances, probably derived from the raw materials and also formed by decomposition due to heating during the process of refining and processing. To the writer's knowledge, wood rosin has not been extensiT7ely used by soap manufacturers up t o the present time. Experience shows that it does not make a soap of as good quality as that derived from gum rosin. Gum rosin is insoluble in water and, like the fatty acids, is freely soluble in alcohol. It is graded according to color. The grades are designated by letters of the alphabet beginning
with the darkest and extending to the palest. The gradeb from G t o N are principally used in the soap industry. These grades, eqpecially G and H rosins, seem to produce somewhat harder soaps than the paler grades WG and WW. Gum rosin reacts readily with caustic alkalies, carbonated alkalies, and oxides of the heavy metals to form soaps. The rosin soaps of the heavy metals are semi-solid, tacky substances that find extensive use in the manufacture of lubricants. Rosin soaps of the alkali metals are very soft, viscous, sticky, and tacky, and have the characteristic aromatic, piney odor of gum rosin; they are freely soluble in water, produce a free copious lather, and have pronounced detergent properties. They are used in the production of hard and soft soaps, never by themselves but always in combination with other fats and oils. Soda soaps of pure rosin do not become hard enough to be used as commercial hard soaps; potash soaps of pure rosin do not acquire the necessary consistency and firmness to be used as commercial soft soaps. Rosin soaps do not rinse freely or completely; they leave the washed articles with a tacky feel and a rosin odor, indicating nonsaponifiable materials, and/or hydrolysis of rosin soap, or both. These tacky, sticky substances, being insoluble in mater, have a marked tendency t o adhere to the washed fabrics and to resist the action of rinsing, thus destroying the fluffiness and softness of garments and rendering them hard
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and ropy. This is very objectionable, especially in the case of rayons, silks, and woolens. For this reason rosin cannot be used in the manufacture of textile soaps or for soaps intended for use in eit'her power laundries or domestic washing machines. The incorporation of rosin in hard laundry soaps imparts to them the characteristic rosin odor, yellow color, and tough, waxy texture which tends to overcome and prevent cracking and breaking when processed in the cake or bar form. It also tends to slow up or prevent the crystallization of the soaps of the harder fatty acids and to render them softer and more readily soluble in laundry practice. For this same reason rosin cannot be used in the production of chipped, flaked, shredded, granulat'ed, or powdered soaps. 13y preventing crystallization, rosin retards drying and interferes with the process of manufacture of this large and important part of the soap industry. It is evident, therefore, that in the field of hard soaps, rosin is restricted t o use in the production of household soaps in bar or cake form. Potash rosin soaps are extensively used in the production of various kinds of smooth and artificial fig soaps. Rosin imparts to these soaps a clear, waxy appearance and consistency considered essential to a high-grade product. Owing to its low cost and free lathering propert'ies, rosin was formerly extensively used and considered an essential constituent in the manufacture of household laundry soaps in combination with tallow, greases, and palm oils. At that time soaps made from these hard fats were hard, brittle, and deficient' in lathering and sudsing properties, owing to their slow solubility in warm wat,er. Rosin served the manyfold purpose of reducing the cost, improving the solubilit'y in warm water and hence the free lathering properties, and of reducing the hardness and thereby improving the texture of the soaps and rendering them less brittle and of a more waxy and tough consistency. I t also improved the color and, by imparting some of its piney odor t'o the soaps, served to cover up the oftentimes disagreeable smell of the hard fats. The rosin in these hard soaps is a t times as high as 60 per cent of the total fatty acid content of t'he soap, depending on the hardness of the fats used.
CAUSEOF DECLINEIS ROSIXSoap PRODUCTION The consumption of rosin by the soap industry has shown a general and a t times marked decline during the last 25 years, for several reasons. The production of rosin fell off because of bhe depletion of the pine forests, while the demand for rosin in other industries, notably the paper and varnish trade, steadily increased and caused a scarcity in supply and a marked increase in price. Thus soap manufacturers had to look about for a cheaper substitute. The increased price of rosin brought it nearer not only t o that of animal fat's but more especially to that of various vegetable oils that were being produced in this country and imported in increasing amount's every year. These vegetable oils included cottonseed, peanut, corn, palm-kernel, coconut, and, more recently, soy-bean oil. The demand from the soap industries spurred on the production of these oils a t lower costs. Many of the larger soap manufacturers became engaged in the processing of these oils for both soap and edible purposes. As the prices of these oils declined to meet the advancing price of rosin, the soap industry turned more and more away from rosin. Another important and possibly more determining factor than cost in bringing about this change was the superior qualities of these veget'able oils in soap making. They were light in color and produced white soaps, were free from odor, and were low in nonsaponifiable matter and other sticky and objectionable materials. Soaps made from them were not only harder than rosin soaps but lathered more freely and rinsed perfectly, without leaving any harmful or objectionable effects on the
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washed fabrics. These soaps crystallized arid dried equally as well as tallow soaps and were thuq adapted for use in the production of textile, chip, flake, shred, and powder soaps. The development of automatic machinery for processing and packaging these chip, flake, and powder soaps greatly reduced costs and enabled the manufacturer to furnish the trade a product which was convenient to use, was quickly soluble, and, on account of chemical composition, possessed superior detergent properties; thus impetus was given to the trend toward merchandising this class of soap products. They seemed to lend themselves to popular forms of advertising and to offer less sales resistance than the cake or bar soap. It was also found that, owing to the free lathering properties of soaps containing high percentages of palm-kernel or coconut oil, these soaps would produce a much superior lather to that of ordinary soap in the hard-water sections of the country; as a result these so-called hard-water soaps have generally displaced other types of soaps in these areas. On the other hand, in soft-water sections the rosin soaps have resisted the advance of these hard-water soaps fairly well. One of our nationally advertised and distributed soaps, of which rosin is an essential constituent, has maintained a fairly constant sales volume for many years. According to the best figures obtainable, the consumption of rosin by the soap industry has declined a maximum of about 60 per cent in the last twenty-five years. There have been times during that period when the consumption has not been off more than hal,f that amount. This is notable in years of depression. As purchasing power decreases, consumers turn more to lowpriced soaps. This was markedly true in 1932. hlanufacturers produced and sold large quantities of low-priced, unwrapped, unpressed, and unadvertised brands of cake soaps, most of which contained a fairly high percentage of rosin. As prosperity returns, consumer purchasing power increases and the sale of advertised packaged soaps increases while that of low-priced cake soaps falls off. This explains a 182,000-barrel consumption in the prosperous year 1928 and a 261,000-barrel consumption of rosin by the soap trade in the depression year 1932. The mean of these two amounts would represent fairly well the average consumption per year during the 1928-32 period or 220,000 barrels, which is about 50 per cent of the 415,000 barrels consumed in 1909. The amount of rosin consumed by the soap industry in the future will depend not only on the comparative prices of rosin and other soap-making fats but also on the comparative sales reqistance between rosin bar soaps and packaged soap products of the chip, flake, powder class, and to a lesser extent on hard-water bar soapq. When exposed to the air, rosin soaps turn darker owing to the oxidation of the unsaturated rosin acids. But they do not become readily rancid from the oxidation of the animal or vegetable fatty acids present, since the rosin seems t o take up the oxygen and prevent the fatty acids from becoming rancid. The rosin acts as an antiovidant or preservative. For this reason small amounts of rosin are added to laundry and toilet soap products t o prevent rancidity. R E C E I ~ E4pril D 2 , 1934
Presented as part of the joint Symposiuin on Naval Stores before the Divisions of Agricultural and Food Chemistry and of Industrial and Engineering Chemistry a t the 87th Meeting of t h e American Chemical Society, St Petersburg, Fla , March 25 t o 30, 1934
