August, 1931
909
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Upon standing several days, no gossypol acetate could be detected even with the microscope. There were present highly refractive substances, perhaps sterol, which were very bi-refringent under the polarizing microscope, but they had none of the characteristics of the yellow gossypol acetate crystals. A second preparation, when examined under t8he polarizing microscope, contained a few yellowish crystalline substances, but they were so limited in amount that positive identification of them as gossypol was impossible. There is apparently little or no gossypol in kapok seed. Analysis of Oil
Another portion of meats, containing 5.7 per cent of moisture, was extracted with petroleum ether, and the extract, after evaporation of the solvent, amounted to 39.9 per cent of the meats. It was a viscid, almost colorless oil of about the consistency of glycerol. No stearin separated from this oil a t room temperature in the course of 2 or 3 weeks. The test with Halphen’s reagent gave an intense ruby-red color, very much more striking than with ordinary refined commercial cottonseed oil. It may therefore be stated that reports that t’he seed oil of C . pentundra (E. anfracfrtosttm) does not give the Halphen reaction (4) are in error. The analysis of the oil extracted by petroleum ether gave the following results: Specific gravity a t 25’/25’ C . . . . . . . . . . . . . . . . 0,9225 1.4691 Refractive index at 25’ C . . . . . . . . . . . . . . . . . . . Saponification value.. . . . . . . . . . . . . . . . . . . . . . 191.6 Iodine number (Hanus).. . . . . . . . . . . . . . . . . . . 94.1 Unsaponifiable matter,’per cent. . . . . . . . . . . . . 0.94 Acid value.. .............................. 9.65 Saturated acids, per c e n t . , . . . . . . . . . . . . . . . . . 17.15 Unsaturated acids, per c e n t . . . . . . . . . . . . . . . . . 76.:32
With the exception of the specific gravity and acid value, all determinations were made in duplicate and closely agreeing results were obtained in each case. From the iodine number and the percentage of unsaturated acids, it was calculated that the oil contained 49.62 per cent of oleic acid and 26.70 per cent of linoleic acid. It will be observed that kapok-seed oil contains a much smaller quantity of saturated acids than cottonseed oil, which contains from 23 to more than 25 per cent. As is t o be expected from the lower iodine number, kapok-seed oil has much less linoleic acid than cottonseed oil. N a t u r e of Proteins in Seed
I n order t o determine the general character of the proteins of the seed, the meats, extracted first with petroleum ether and then with sulfuric ether, were dried a t room temperature, ground to pass a 60-mesh sieve, and then extracted successively three times with distilled water, three times with 5 per cent sodium chloride solution, three times with 10 per cent sodium chloride polution, once with 0.3 per cent sodium hydroxide solution, and once with 60 per cent alcohol, The amount of nitrogen extracted by these solvents was determined as well as the amount in the original meats and that left in the residue after extraction. The extracts were separated from the undissolved material by centrifugation. The decanted supernatant fluid was then filtered through hardened filter paper by suction; all the extracts, nevertheless, remained somewhat opalescent, undoubtedly a source of a slight error. The distribution of nitrogen, as determined by the Ter h,leulen-Heslinga method ( 2 ) , was found to be as follows: 7
Moisture content.. . . . . . . . . . . . . . Total nitrogen.. . . . . . . . . . . . . . . . Water-soluble.. . . . . . . . . . . . . 21 .O NaCl (5~o)-soluble... . . . . . . 45.0 NaCl (10%)-soluble. . . . . . . . 3.5 Alkali (0.2y0 Na0H)-soluble 3.9 0.9 Alcohol (60%)-soluble. . . . . . Undissolved. . . . . . . . . . . . . . . 28.0
0
% 8.90 9.05
The figure for nitrogen remaining unextracted in the residue is probably too high, because the residue was inevitably slightly contaminated with filter-paper fibers, which made sampling unsatisfactory. This is probably why the nitrogen of the table totals to more than 100 per cent. The determination of nitrogen distribution was repeated in the same manner, except that after removal of the oil the residue was heated for a short time a t 100” C. to dry it. This may have rendered some of the protein insoluble in water and salt solution, thus increasing the amount soluble in sodium hydroxide. Extraction with 60 per cent alcohol was omitted and extraction was made only with 15 per cent salt solution. The results were as follows: Moisture content., . . . . . . . . . . . . . Total nitrogen.. . . . . . . . . . . . . . . . Water-soluble.. . . . . . . . . . . . . NaCl (157,)-solubIe.. . . . . . . Alkali (0.2% Na0H)-soluble Undissolved., . . . . . . . . . . . . .
% 16.50 41.15 13.45 27.10
% 8.19 8.36
The figure for water-soluble nitrogen is probably too low owing to an error of manipulation. This is probably the reason why the total is less than 100 per cent. The water extract contains an appreciable amount of globulin, for it yields a precipitate when somewhat more than half saturated with ammonium sulfate. A precipitate also forms on dialysis. Whether it also contains albumin could not be determined with certainty; if present, it can only occur in slight amount, The salt extract contains an abundance of globulin which is completely removed by dialysis. The filtrate from the precipitated globulin contains no appreciable amount of protein. The globulin is also precipitated a t a little above half saturation with ammonium sulfate. Attempts to separate the globulin into two fractions, as was done by Jones and Csonka (a) for cottonseed, failed. Possibly with more material than was available such a separation might succeed. On heating, the salt extracts behaved somewhat in the manner described for cottonseed by Jones and Csonka (3). At about 55” C. the extract became cloudy. It was filtered and heated further. The filtrate became opalescent above 90” C. The glutelin extracted by alkali was not further studied. None of the proteins extracted were purified, nor was the non-protein nitrogen determined. Kevertheless, it may be said that the distribution of nitrogen in kapok seed is similar in a general way to that of cottonseed as determined by Jones and Csonka. The only apparent difference is that kapok seed probably contains more nitrogen in a form extracted neither by salt solution nor by dilute alkali. Like cotton seed, kapok seed contains principally a globulin or mixture of globulins, and a glutelin. It contains no prolamin and probably no albumin. Its globulins are difficult to coagulate by heat. Literature Cited (1) Caruth, F. E., J . Am. Chem. Soc., 40, 647 (1913). (2) Griffing, E. P., and Alsberg, C. L., Ibid., 63, 1037 (1931). (3) Jones, D. B., and Csonka, F. A.. J. Bioi. Chem., 64, 673 (1925). (4) Lewkowitsch, J., “Chemical Technology and Analysis of Oils, Fats, and Waxes,” 6th ed., Vol. 2, p. 185. Macmillan, 1921.
Correction-In the article on “Products of Corrosion of Steel,” by H. 0. Forrest, B. E. Roetheli, and R. H. Brown [IND.ENG. CHEM.,23, 650 (1931)] the authors state that the next to last sentence in the last paragraph of the synopsis should read “when the pH in the liquid film is allowed to build up because of slow diffusion of hydroxyl ions from the liquid film to the main body of the liquid (due to poor agitation), ferrous hydroxide will be precipitated and subsequently magnetic oxide of iron will be formed.”
