Chemical examination of watermelon seed / by Frederick B. Power and Arthur H. Salway.

  • Power, Frederick B. (Frederick Belding), 1853-1927.
Date:
[1910]
Catalogue details

Licence: Attribution 4.0 International (CC BY 4.0)

Credit: Chemical examination of watermelon seed / by Frederick B. Power and Arthur H. Salway. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    weight of potassium permanganate. The product of oxidation was digested with large quantities of ether, which extracted a substance melting at 126-128° and which, after crystallization from alcohol, sep- arated in small, glistening leaflets melting at 128°. o. 1039 gave 0.2594 C02 and o. 1075 H20. C = 68.1; H = 11.5. CjgHaaOj requires C = 68.4; H = n .4 per cent. This substance was evidently dihydroxystearic acid, and its formation established the presence of oleic acid in the mixture of liquid acids. The oxidation product, after extraction with ether, was heated with large quantities of water, and the liquid filtered while hot. These de- posited a pure white, crystalline substance, melting at 154-155°, which, after crystallization from alcohol, separated in small, thin needles, melt- ing at the same temperature. 0.1138 gave 0.2574 C02 and 0.1068 H20. C = 61.7; H = 10.4. C^H^Oe requires C = 62.1; H = 10.3 percent. This substance was thus identified as tetrahydroxystearic acid (sativic acid), and its formation established the presence of linoleic acid in the mixture of liquid acids. As no hexahydroxystearic acid could be isola- ted from the product of oxidation, it may be concluded that linolenic acid is not a constituent of the oil. II. Examination of the Press-cake. The so-called “press-cake” resulting from the expression of 22.5 kilo- grams of watermelon seeds, deprived as completely as possible of the . shells, amounted, as previously noted, to 3.88 kilograms. This was completely extracted with hot alcohol, when, after the removal of the greater portion of the alcohol, a thin, dark brown, oily extract was ob- tained, amounting to 1644 grams. It evidently contained a considera- ble quantity of fatty oil which had escaped expression from the seed, and which was removed by treating the extract with light petroleum (b. p. 30-45°). The amount of fatty oil obtained in this way was 1340 grams, thus corresponding to 81.5 per cent, of the total alcoholic ex- tract. Its constants were as follows: d 20°/20° = 0.9328; saponifica- tion value, 191.4; iodine value, 112.7. The fatty oil obtained from the press-cake, as above described, would naturally be expected to be similar in composition to that obtained from the seed by expression, and its examination proved this to be the case. It was found to contain a very small amount of a phytosterol, melting at 160°, and the mixed fatty acids obtained on hydrolysis possessed the following constants: m. p., 34°; d 50°/50° = 0.8916; neutralization value, 197.6; iodine value, 129.5. These acids, like those obtained from the expressed oil, consisted of a mixture of palmitic, stearic, oleic and lin- olic acids. The portion of the alcoholic extract which remained undissolved by