Electrokinetic phenomena

1. 1. The electrical properties of quartz particles covered with material adsorbed from ragweed extracts are those typical of ampholytes. 2. 2. The isoelectric point of these particles covered with a fresh extract was at pH 3.9. On standing this shifted to pH 4.3 where it was stabilized for some time. 3. 3. Experiments with paraffin oil and collodion particles showed that these particles acquired similar amphoteric surface properties in ragweed extracts, corresponding exactly with those found when the adsorbent was quartz. 4. 4. The titration curves of ragweed extracts were typical of solutions of proteins with a maximum acid-binding capacity near pH 2.6. 5. 5. The data obtained are evidence supporting the point of view that the skin reactive constituent in ragweed extracts is protein-like in nature.