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

  • Osborne, Thomas B. (Thomas Burr), 1859-1929.
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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    \ opalescent and neutral, it is most probable that they were col- loidal or false solutions caused by edestin bichloride, formed by a local over-excess of acid, which was subsequently repre- cipitated on coming into contact with uncombined edestin. By 6 cc. some edestin was dissolved, but the lower acidity of this portion indicates that the whole of this was not brought into solution by the acid. From 6cc. upward, a uniformly increasing quantity of edestin passed into solution, until only an insignificant amount remained undissolved by 14 cc. If edestin has a molecular weight of about 14,500 and forms an insoluble chloride with one molecule of hydrochloric acid, about 6cc. of centinormal hydrochloric acid should convert one gram of an air-dry preparation into this chloride. In Table XII it is seen that the edestin does not dissolve with less than 6cc. of acid. Strictly, none should dissolve with less than 7 cc., but as this preparation had an acidity of about I ,cc. per gram, the hydrogen ions causing this ought, in so dilute a solution, to contribute equally with those of the hydrochloric acid in reacting with the edestin, and hence a corresponding quantity should be dissolved. That this soluble acid compound of edestin contains twice as many molecules of acid as the insoluble acid compound, is shown by the rate at which the acidity of the solution of this substance increased in comparison with the rate at which the acid was added in these experiments. Thus, the solution pro- duced by 10 cc. of acid neutralized 1.80 cc. more alkali than that produced by 9 cc., although but 1 cc. more acid had been added; that with 11 cc. also neutralized 1.80 cc. more alkali than that with 10 cc.; that with 12 cc. neutralized 2 cc. more alkali than that with 11 cc.; that is, after the whole of the edestin was converted into the insoluble chloride, each molecule of acid subsequently added brought into solution another molecule of acid which had been previously combined with the edestin as an insoluble chloride. If edestin has a molecular weight of about 14,500, each cc. of centinormal acid in excess of 7 cc. should dissolve 0.1450 gram. The quantity actually dissolved by each cubic centimeter of acid in excess of 7 cc. falls considerably short of this, chiefly owing to the formation of the more basic derivative, edestan, men- tioned on page 417.