Studies; Reprints Volume 37

Studies; Reprints Volume 37

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1921 edition. Excerpt: ...of this problem. We have seen in the preceding papers of this series that a collodion membrane not treated with a protein always assumes a negative charge when in contact with a watery solution, even. if this solution is acid. This was demonstrated in two ways, first by electrical endosmose,1 and, second, by common osmosis.3 The experiments with electrical endosmose do not lend themselves so well to the exact determination of that hydrogen ion concentration at which the membrane becomes positive on account of electrolysis and the secondary chemical reactions at the electrodes. The method of common osmosis is free from this source of error. When we separate a watery solution from pure water by a collodion membrane the pure water difiuses into the solution at a rate which is not only a function of the gas pressure of the solute but also of the electrostatic forces of the ions in solution. The rate increases with increasing valency of the anion and diminishes with increasing valency of the cation. When, however, the collodion membrane has been treated for some time with a protein it assumes a positive charge when the hydrogen ion concentration exceeds a certain value; and in this case the watery phase of the double layer assumes a negative charge. This is proved by the fact that when we separate a watery solution with a sufliciently high hydrogen ion concentration from pure water by a collodion membrane treated with a protein, the water will diffuse into the solution at a rate increasing with increasing valency of the cation and diminishing with increasing valency of the anion. It is not diflicult to find out by this method the critical hydrogen ion concentration at which the reversal in the sign of charge of the membrane occurs. The...show more

Product details

  • Paperback | 174 pages
  • 189 x 246 x 9mm | 322g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236952154
  • 9781236952158