A text-book of physiological chemistry / by Olof Hammarsten ... with the collaboration of S. G. Hedin ... Authorized translation from the author's enl. and rev. 8th German ed., by John A. Mandel ... Total issue, 11 thousand.

  • Hammarsten, Olof, 1841-1932.
Date:
1914
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Licence: Public Domain Mark

Credit: A text-book of physiological chemistry / by Olof Hammarsten ... with the collaboration of S. G. Hedin ... Authorized translation from the author's enl. and rev. 8th German ed., by John A. Mandel ... Total issue, 11 thousand. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    tionable whether there exists any proteid body which is soluble in water without the aid of mineral substances. Nevertheless it has not been thus far successfully proved that a native proteid body can be prepared perfectly free from mineral substances without changing its constitution or its properties.1 As previously stated, the albuminous bodies are amphoteric elec- trolytes, and are polyacidie liases as well as polybasic acids. The base- and acid-combining powers of various proteids have been the subject of numerous investigations which cannot be given in short. In regard to various methods used in such investigations as well as to the dissociation of protein salts we refer especially to the work of T. B. Robertson.2 The proteids can be salted out from their neutral solutions by neutral salt? (NaCl, Na2S04, MgS04, [NH4]2S04, and many others) in sufficient concentrations. By this salting out the properties remain unchanged and the process is reversible, as on diminishing the concentration of the salt the precipitate redissolves. The various proteids act in an entirely different manner toward the same salt, and also for one and the same proteid the behavior toward different neutral salts is different, as some cause a precipitate, while others on the contrary do not precipitate. The behavior of various proteids with one and the same salt, such as MgSCU or (NEU^SO-i, is often made use of in the isolation of the proteid, and special methods of separation are based' upon fractional precipitation. It has been shown that these methods may lead to great errors, and give good results only under special conditions.3 The conditions are different from those of salting out, when the pro- teid solution is precipitated by salts of the heavy metals. Here the precipitates (often called metallic albuminates) are not true combina- tions in constant proportions, but are rather to be considered as loose adsorption compounds of the proteid with the salt.4 These reactions are irreversible in so far that dilution with water or removal of the salt by means of dialysis does not restore the unchanged proteid. On the other hand the precipitate, at least in certain cases may be redissolved in an excess of the salt solution or of the proteid solution, and in this sense the process is a reversible one. 1 See E. Harnack, Ber. d. d. chem. Gesellsch., 22, 23, 25, and 31; Werigo, Pfliiger's Archiv, 48; Biilow, ibid., 58; Schulz, Die Grosse des Eiweissmolekuls, Jena, 1903. 2Ergeb. d. Physiol. 10; Journ. of physical Chem., 14, 15, and Journ. of biol. Chem., 9. 3 See Cohnheim, Chemie der Eiweisskorper, 3. Aufl., 1011; Pinkus, Journ. of Physiol., 27; Pauli, Hofmeister's Beitrage, 3, p. 225; Halsam, Journ. of Physiol., 32. 4 See Galeotti, Zeitschr. f. physiol. Chem., 40, 42, 44, and 48 and Bonamartini and Lombardi, ibid., 58. See also the opposed views of Linpirh. ibid, 74.