The solubilities of the pharmacopœial organic acids and their salts / by Atherton Seidell.

  • Seidell, Atherton, 1878-1961.
Date:
[1910]
Catalogue details

Licence: In copyright

Credit: The solubilities of the pharmacopœial organic acids and their salts / by Atherton Seidell. Source: Wellcome Collection.

    15/104 (page 13)
    ually added to mixtures of known volumes of alcohol and water until an opalescence was observed. The experiments were made at 20°. Furthermore, the water and ethyl acetate used were each pre- viously saturated with the other. It would therefore be necessary to apply a calculated correction factor to the results in order to bring them to the terms desired for the present purposes. In view of the possible uncertainty which might arise through such calculations it appeared more desirable to make new determinations upon materials of highest purity. The ethyl acetate used was prepared from the Kahlbaum product by allowing it to stand over calcium chloride for a day, filtering, and distilling. That part of the liquid, amounting to nearly one-half of the whole, which distilled between 75° and 76° (corrected) was reserved for the solubility determinations. The specific gravity of this frac- tion was 0.8984 at 15°, 0.8948 at 20°, and 0.8915 at 25°. The aque- ous alcohol solutions were those prepared, as already mentioned (p. 10), for the solubility determinations of all the compounds de- scribed in this bulletin. The method used in the present case was as follows; The accurately measured portions of the aqueous alcohol solutions were placed in small Erlenmeyer flasks and brought to as near 25° as possible; a burette was filled with the purified ethyl ace- tate, which had been allowed to remain in the constant temperature bath at 25° for an hour or longer. The temperature of the room at the time the determinations were made was 22° to 24°. The ethyl acetate was added very gradually to the aqueous alcohol and the solu- tion shaken between each addition. -The saturation point was indi- cated by the appearance of a distinct opalescence, less than 0.05 cubic centimeter being sufficient to cause the change from clear to cloudy condition in most cases. Satisfactory concordance in dupli- cate determinations was obtained. The flasks containing the slightly opalescent saturated solutions were suspended in the constant tem- perature hath for an hour or longer, after which time the specific gravities of the solutions were determinefl by the pycnometer method. The results of the determinations are given in Table No. II and show that ethyl acetate is completely miscible with aqueous alcohol solu- tions of about 40 weight per cent or more concentration. The curve for this compound in Plate No. I shows that the solubility increases gradually at first and then very rapidly, with increase of alcoholic strength of the solvent.