FEBRUARY, 1937
INDUSTRIAL AXD ENGINEEHING CHEMISTRY
I-mil coating
%mil gosting: magnified section. x 2.5
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6-mil C O s 6 n K
The PBD& were exposed outdoors for 23 months: the 0~6-rnilaoating failed by peeling after 13 months of ~ ~ p o ’ l ~ u m .
FIQURE 5. EFFECTOF THICKNESS ON ESPOSUREBEHAVIOR OF
the manner in which adherence is destro ed may vary and thus sffect the character of the final visual k r e , such as flaking, waling, or peeling. Inasmuch as contact with water appears to be necessary to bring about such interfacial reactions, BS evidenced by the fact that none of the finishes exposed indoors showed adherence losses even after 2 yeare, the suggestion IS offered that instability of adhereuce might be revealed quickly by immersing a young-hiah specimen in water to accelerate interfacial reactions snd.then subjecting it to an impact test. 3. A finish, however, may also lose effective adherence to its base even though its specific adhesion may not be affected. This loss may be brought about by the development of shrinkBee forces sufficientto urd1 off a CostInE from its snchoraee swnt&eously. Evidence d such shrink-; forces has been Gbtahed by coatin thin metal foils and noting the degree of coiling of the foils devekped as aging progressed. Additions1evidence of such forces is revealed bv the reduction in distensibilitv of a finish with increase in thickness of coating. 4. The chief virtues of the physical approach t o test,ing the quality of a finish appear to be: (a) It m2tt.erially expedit,es tho
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SYNTHETIC BAKIVG ENAMEL (MATERIALN )
point at which evaluation can be made, and (h) a deeper insight into the mechanism of finish degradation is provided. The results of physical test, when con led wit.h the knowledge of the eom osition and formulation o f t h e finishing material, should aeceferate further advances in paint technology.
Literature Cited (1) h i t . H. G.,Bell Lab. Record, 14 ( i )216-17 , (1936). (2) Pfund, A. H., Proc. .4m. SOC.Testin? Xalerials, 25, 392.402 (1929). (3) Sohuh, A. E., IND. ENU.CHESI.,23, 1846-52 (1931). (4) .~ Schuh, A. E., and Kern, E. W., Iao. Eno. CHEX.,A n d Ed.. 3, 72-6 (1931). (5) Sohuh, A. E., m d Theuerer, H. C . , ZbiL, 6,91-7 (1934). (6) Ibiil.. 9, 9 (1937). R ~ c s r v Segteniber ~o 14. 1936. Presented beioie the Division oi Paint and Vainish Chemistry at the 9zod Meeting 01 tbe Ameriaaii Chernioal Sooiety. Pittsburgh, Pa., September 7 t o 11, 1938.
Dehydroascorbic Acid Reductase E. F. ROHMAN m n N. H.SANBORN National Canners Association, Washington, D. C. EZSSOSOFF (g) in 1921, while attempting to determine whether the antiscorbutic principle of raw potatoes resides in the juice or in the insoluble portion, found so little in either that he at once recognized that it was rapidly being inactivated in his process of extracting the juice. The writers’ early studies (7) of the vitamins in canned foods brought out the point that vitamin C is lost during storage of raw produce and that such loss is arrested by canning (4) and greatly accelerated by the shredding of carrots (5). These Gndings suggested enzymic activity. Yzent-Gydrgyi (8) stat.es that in minced cabbage leavcs the hexuronic acid present is reversibly oxidized catalytically in a short time by an enzyne which he tenns “liexoxidase,” hut lie was unable to demonstrate the reduction of thc reversibly oxidized form by enzymic activity. Kertesz, Dearborn, and Mack (3) recently ascrihed the loss of ascorbir acid in raw frozen peas to the activity oi an crlaymc dt-signated by them “ascorbic acid oxidase.” These are all oxidative effects; hut, since plant life is endowed with an ~,xidation-redoctionsystem, there must 1)c an
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opposite reducing effect. In 1928 the writers pointed out (1) that raw frozen vegetables were not a commercial feasibility because of the off-flavors that developed. Subsequently (6) these off-flavors, as well as similar ones developed in other conditions involving a ruptured plant cell, were ascribed t.o anaerobic enzymic activity which involves reduction. During the p a t seaSon in working with peas, observations were made that suggested a technic to illustrate in raw pea juice tlic restoration of reducing value to 2,6-dichlorophennlindophenol after its destruction is caused hy aeration alone or is catalyzed by copper or by oxidation with the dye itself. If this dye is a ineasure of ascorbic acid, a basis on which many workers are puhlishing data, then there exists in raw pea juice a “dehydroascorbic acid reductase.” In the writers’ experiments it resultcd in tire production of the equivalent of 15 mg. ascorbic acid per 100 ec. in 5 to 6 hours. Hcated pea juice or raw cabbage juice did not yield the same results. In fact, a loss of dye-reducing effect was found instead. This is not to he construed as a coinnient on the degree of
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accuracy with which 2,6-dichlorophenolindophenolmeasures either vitamin C or ascorbic acid. Attention may be called, however, to recent claims (1) of another substance in the antiscorbutic fraction quite different in constitution and in physiological activity from ascorbic acid. Studies in this connection will be pursued here to include other vegetables and, if a procedure is found to secure a reducing effect sufficiently large and Sufficiently controllable, to determine biologically whether increased reducing effect is accompanied by an equivalent antiscorbutic effect. The fact that a reducing value to 2,6-dichlorophenolindophenol is produced in raw succulent pea juice but not in cabbage juice deserves further consideration with reference to the fact that ascorbic acid is produced in the germination of pea seeds.
VOL. 29, NO. 2
Literature Cited (1) Armentano, L., Bents&th, A., BBres, T., Ruszny&k, Iatvan, and Szent-Gyorgyi, A., Deut. med. Wochschr., 62, 1326 (1936). (2) Bezsaonoff, M., c m p t . rend., 172, 92 (1921). (3) Kertesz, 2.I., Dearborn, R. B., and Mack, G . L., J . Biol. Chem., 116, 717 (1936). (4) Kohman, E. F.,Eddy, W. H., and Carlsson, Victoria, IND.ENQ. CHEM.,16, 1261 (1924). (6) Kohman, E. F., Eddy, W. H., and Gurin, C. Z., Ibid., 23, 808 (1931). (6) Kohman, E. F.,and Sanborn, N. H., Ibid., 26, 773 (1934). (7) Natl. Canners Assoc., Research Lab., Canner, 68. Pt. 2 , Convention No., 187 (1929). (8) Szent-Gyiirgyi, A., J . B ~ O Chem., Z. 90, 385 (1931). RECEIVED January 18, 1937.
Vitamin D Content of Menhaden ,Fish Oil W.C. SUPPLEE University of Maryland, College Park, Md.
T
HE tremendous requirements of the feed industry for vitamin D supplements give significance to evidence of new sources of vitamin D which offer possibilities of being more economical than those now utiliied. Menhaden oil, a product of American fisheries, is ordinarily marketed for industrial purposes at a much lower price than that of cod liver oil and sardine oil sold to the feed industry as sources of vitamin D. The potential value of menhaden fish oil as a source of vitamin D has been indicated by the work of several investigators (2-6). Supplee and Lee (6) tested samples of commercial menhaden oil by the chick assay method and found them to be as potent in vitamin D as ordinary grades of cod liver oil now used for poultry feeding. The present paper gives the results of the assay of two samples of menhaden oil speoially prepared by the author and fully substantiates previous work indicating the value of this product as a vitamin D carrier.
Menhaden fish oil tested by the chick assay method was found to be relatively high in vitamin D content. A sample of oil from so-called thin fish was found to be at least twice as potent as a sample of oil from medium fat fish from the same catch. Oil from thin fish gave a bone ash of 45.84 per cent when fed at a per cent level, and medium fish oil gave a value of 45.91 per cent at a l/4 per cent level. The tentative 4-week chick assay method of the Association of Official Agricultural Chemists was used.
Biological Assay The Association of Official Agricultural Chemists’ tentative chick assay method for vitamin D carriers was used in this study (1). The method in detail as applied in this work is as follows : Groups of one-day-old white Leghorn chickens are placed in screened-bottom biological cages. One group is reserved for negative control purposes, and one or more additional groups are reserved for each material to be assayed. Distilled water is kept before the chicks at all times. A sufficient quantity of a basal rachitic ration to provide for the entire feeding period is prepared as shown in Table I.
Preparation of Samples Live fish were taken from the net and sorted roughly into two sizes-small or “thin” fish which yield a very small quantity of oil, and larger, medium fat fish. A suitable quantity of each of these two types was cooked immediately with steam for about 8 minutes to loosen the tissues and then pressed thoroughly to express the oil. The oily juice thus obtained was allowed to stand in large glass cylinders until the oil separated cleanly. The oil was drawn off, strained through absorbent cotton, and finally filtered through paper. The purified oil~l,which were of high quality (extremely low in free fatty acids, light in color, and practically odorless) were stored in glass bottles in an electric refrigerator until Mted.
TABLEI. BASALRACHITIC RATION Ground yellow aorn Pure wheat flour middlings Crude domestio acid-precipitated oasein Calcdm carbonate ( reoipitated) Calcium phosphate grecipitated) Iodized spit (0.02% potassium iodide) Nonirradisted yeast (7% minimum nitrogen)
Parts by weight 69 25 12
1 1 1
1
The test rations are made up by adding the desired percentages of vitamin-D-bearing oil to the basal rachitic ration. Sufficient corn oil is also added to those rations containing the smaller amounts of test oil to bring the total added oil
