Tyndall cone

T.W., abbrev. (Teile(n) Wasser), parta of water. Tyndallkegel, m. Tyndall cone. 

Microemulsions can be produced in several ways. One. simple recipe is to use 7 cm3 of household liquid detergent (neat or diluted 1 2), 14 cm3 of white spirit, and 4 cm3 of n-pentanol (amyl alcohol) or n-butanol. The components are mixed gently and allowed to separate into two phases. After several hours the upper oil phase becomes clear but (see Appendix II) exhibits a strong Tyndall cone. This indicates the presence of microemulsion droplets of colloidal size. 

Observe that both the gold sol and the ferric hydroxide sol appear quite dear when viewed in ordinary light. Now pass a beam of light through each of them and observe a Tyndall cone. Suitable light sources are a beam from a slide projector or, in a darkened room, a beam from a hand torch. Similar observations can be made with diluted samples of the sulphur and silver bromide sols and with microemulsions. 

Observe a similar Tyndall cone by. shining a beam through a developing sulphur sol. If a low-power Hc/Nc laser is available, observe the scintillations during the formation of the sol (Chapter... 

One phase (mechanically homogeneous). 2. Optically empty. No Faraday-Tyndall cone. 3. Solute particles less than 1-5 mp in diameter. 4. No Brownian movement. 5. Solute particles show no siuface properties other than the Baman effect. More than one phase (mechanically heterogeneous). Optically dense. Faraday-Tyndall cone when illuminated transversely. Disperse particles range from 6 mp to 100 mp. Particles show Brownian movement. Disperse particles show surface properties and carry a surface charge. 

Let us say, in passing, that Mr. Tyndall, in a given lesson, in 1854, with Londres , varied the shapes of these films by receiving the jet in small hollow cones of various openings then, when the load is moderated, the films are shaped so as to appear like vases. 

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