Gold number
In 1901 Richard Zsigmondy defined the gold number as the amount of protective colloid that is no longer sufficient to prevent the color change from red to violet in 10 cm³ of a colloidal gold solution after adding 1 cm³ of ten percent saline solution. The amount in milligrams is the gold number of the protective colloid. In this definition, the hydrogen concentration of the hydrosols and the protective colloids is not taken into account.
The lower the gold number, the greater the protective effect to prevent the particles from clumping together in the solution.
| Protective colloid | Gold number |
|---|---|
| Gelatine , glue | 0.0001 - 0.01 |
| casein | 0.0001 - 0.01 |
| Gum arabic | 0.002 |
| hemoglobin | 0.03-0.07 |
| Strength | 0.05 |
| Dextrin | 0.05 |
| Tragacanth | 2 |
Individual evidence
- ↑ Richard Zsigmondy: The bright red gold solution as a reagent on colloids . In: Journal for Analytical Chemistry . tape 40 , no. November 11 , 1901, p. 697 , doi : 10.1007 / BF01334022 .
- ↑ a b c d e Eberhard Sauer: Chemistry and manufacture of animal glue and gelatine. Springer, 1858, ISBN 9783642858833 , p. 90 ( limited preview in Google book search).
- ↑ a b Arnold Berliner , Karl Scheel : Physikalisches Handwörterbuch 2nd edition, Springer, 1932, ISBN 9783642996436 , p. 474 ( limited preview in the Google book search).
- ↑ a b Hans Wolfgang Behm : Colloid chemistry. Generally understandable introduction to the realm of finely divided substances. Franckh'sche Verlagshandlung , Stuttgart 1925.