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

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

Licence: In copyright

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

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    0.1060 gave 0.2968 C02 and 0.1201 H20. C = 76.4; H = 12.6. Ci8H3602 requires C = 76.1; H => 12.7 percent. C20H40O2 requires C = 76.9; H — 12.8 per cent. This substance thus appeared to consist of a mixture of stearic and ara- chidic acids, and the separation of the latter in a pure state was subse¬ quently accomplished by the fractional distillation of the solid portion of mixed fatty acids. On distilling the solid acids under diminished pressure, they began to boil at 2300/18 mm., but nearly the entire amount passed over between 233 and 240°/i8 mm., while a small final fraction was collected at 240-250°/i8 mm. The last-mentioned fraction readily solidified on cooling, and was then crystallized twice from ethyl acetate, from which it separated in rosettes of glistening leaflets, melting at 76-78°. 0.0935 gave o.2633 C02 and o. 1077 H20. C = 76.8; H = 12.8. C20H40O2 requires C =* 76.9; H ■= 12.8 per cent. The identity of this substance as arachidic acid was thus established. The fraction of acid distilling at 230-233 °/18 mm. melted at 59-60°, while that collected between 233 and 240°/i8 mm. melted at 62-64°. Both of these fractions consisted of mixtures of palmitic and stearic acids. The liquid portion of the mixed fatty acids was highly unsaturated, and, like the corresponding product from the expressed oil of the seed, evidently consisted of a mixture of oleic and linoleic acids. Portion oj Alcoholic Extract Insoluble in Petroleum (B). This portion of the original extract of the shells formed a black, resin¬ ous mass, amounting to 150 grams. It was mixed with water and dis¬ tilled with steam, but the distillate contained only traces of volatile acid. The contents of the distillation flask then consisted of a light yellow, aqueous liquid and a quantity of a black resin. These were separa¬ ted by filtration and the resin well washed with water. The Aqueous Liquids. The above-mentioned, yellow, aqueous liquid was repeatedly extracted with ether, which removed about 1 gram of a brownish yellow oil. On digesting this product with water, the resulting liquid gave a greenish coloration with ferric chloride. The oily product was practically insolu¬ ble in water and only partially soluble in sodium carbonate, but dis¬ solved completely in a solution of sodium hydroxide, and was therefore phenolic in character. It was distilled under diminished pressure, whereby some resinous material was removed, and then benzoylated. A crystal¬ line solid melting at 205-210° was thus obtained, but the amount was much too small for further examination. The aqueous liquid was subsequently treated with a slight excess of basic lead acetate, which yielded a relatively small amount of a yellow¬ ish precipitate. This was collected, washed, suspended in water, and decomposed by hydrogen sulphide. On filtering the mixture a liquid