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

  • Frederick Belding Power
Date:
[1910?]
Catalogue details

Licence: In copyright

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

    6/20 page 362
    mixed fatty acids, a portion was heated for some time at 1000 under diminished pressure, in order to remove the last traces of ether, after which the following results were obtained: M. p. (complete fusion), 350; d 50°/50° = 0.8894; neutralization value, 198.2; iodine value, 118.2. Optically inactive. A determination of the acetyl value indi¬ cated the absence of hydroxy acids. The mixed .fatty acids, which consisted of a liquid and a solid portion, were first partially separated filtration with the aid of a pump. The solid acids were then fractionally crystallized from alcohol until no further separation could be effected by this means. The least soluble fraction melted at 66-68°, and was considerable in amount. In order to ascer¬ tain whether this fraction was homogeneous, it was dissolved in hot alco¬ hol and a measured portion of concentrated, aqueous barium acetate added, drop by drop, with constant stirring. The mixture was then fil¬ tered, while still hot, with the aid of a pump, and the precipitate washed with a little hot alcohol. The whole operation was then repeated, and in this manner four successive fractions of barium salt were obtained. The acids liberated from each of these fractions were crystallized once from alcohol, when they had the following melting points: 69-70°, 69-70°, 67-69°, 65-67°. The acid melting at 69-70° separated in glistening, pearly leaflets and was analyzed: o. 1267 gave 0.3522 C02 and o. 1448 HaO. C = 75.8; H = 12.7. 0.5155 neutralized 18.1 cc. 0.1 N KOH. Neutralization value = 197.o°. C18Hj602 requires C = 76.1; H = 12.7 per cent. Neutralization value = 197.5. It is thus evident that the substance melting at 69-70° was stearic acid, and that no acid of higher carbon content was present. All the portions of acid obtained in the course of the original frac¬ tionation which melted below 66-68° were united and fractionally pre¬ cipitated with barium acetate in the manner previously described. Six fractions of barium salt were thus obtained, from which the acids were subsequently liberated. The last of these fractions of acid was oily, and to a large extent unsaturated, while the remaining five fractions, after being once crystallized from alcohol, melted at 66-68°, 65-67°, 65-67°, 64-66°, and 57-58°, respectively. Each of these fractions was titrated, with the following results: Fraction 1 (m. p. 66-68°), 0.2661 neutralized 9.5 cc. 0.1 N KOH. N. V. — 200.3. Fraction 2 (m. p. 65-67°), 0.1356 neutralized 4.8 cc. 0.1 N KOH. N. V. = 198.6. Fraction 3 (m. p. 65-67°), 0.1828 neutralized 6.5 cc. 0.1 N KOH. N. V. — 199-5- Fraction 4 (m. p. 64-66°), 0.0876 neutralized 3.15 cc. 0.1 N KOH. N. V. — 201.8. Fraction 5 (m. p. 57-58°), 0.1707 neutralized 6.35 cc. 0.1 N KOH. N. V. — 208.7.
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