The basic character of the protein molecule and the reactions of edestin with definite quantities of acids and alkalies.

  • Thomas Burr Osborne
Date:
[1900]
Catalogue details

Licence: In copyright

Credit: The basic character of the protein molecule and the reactions of edestin with definite quantities of acids and alkalies. 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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    ant precipitate, most of which dissolved when more of the salt passed into the solution, which was then filtered and dialyzed for 40 hours, whereby its salt content was reduced to 2 per cent., and the edestin was precipitated in beautiful crystals. These were filtered out, washed with 50 per cent, alcohol and finally with absolute alcohol and dried over sulphuric acid, giving 37 grams of a perfectly crystallized, dazzlingly white preparation, 22, which was mostly soluble in pure water, and wholly soluble in sodium chloride solution. To neutralize to phenolphthalein, a quantity of this prepara- tion corresponding to one gram of the water and ash-free sub- stance, 1.22 cc. of decinormal potassium hydrate solution was required, corresponding to an acidity which, as we shall see later, is that of a mixture containing a small proportion of the water-insoluble with a large proportion of the water-soluble, edestin compound. Twenty grams of this preparation, air-dry, were then treated with 600 cc. of pure water, 220 cc. of centinormal potassium hydrate solution added, and the voluminous precipitate filtered out and washed with 250 cc. of water. The filtrate and wash- ings, when evaporated, left a residue, which had the following composition: Table VII.—Potassium Salts Formed by Neutralizing Edestin Prep- ARATION. 22. In per cent, of the Gram. Inorganic matters. Organic matters 0.0185 Potassium carbonate 0.0020 1.19 Potassium sulphate 0.0065 3-89 Potassium chloride 0.1398 83-51 Sodium chloride - 0.0191 n.41 0.1859 100.00 Although the free edestin had been only superficially washed, we find over 85 per cent, of the added potassium to be con- tained in these salts, 95 per cent, of which is present as chloride. The proportion of sulphate to chloride in these salts is less than 2 molecules of the former to 100 of the latter. Although this preparation was nearly free from sulphate, nevertheless, a perfectly pure chloride was not obtained in this way. Twenty grams of that part of the edestin, which, as already described, did not dissolve in water, were suspended in 600 cc.
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