str (104)

but there is no doubt that structural viscosity does occur vrith many materiais.

Reiner gives flow curves for rnbber toluene sols. The first stage is linear from the origin; but aft er a certain stress is reached, upward curyilinearity takes place, followed by inflection to downward curviłmearity. Finally a condition of lineaiity, directed to the origin, is again asymptotically

¹ Ostwald replies to these critirisms ia Koli. Zeits., 1929,

xl\u.,

mi ura psutictes m 3. concentric cnźnds' apparatns, at wdl bęiow the ordinaiT crrirąi velodty: and Hatschek and Jane ind a iarge apparent increase in the yiscosrty of ammnnńm oleate at high stress, which they attiibnte to a srmilar canse. The anthor believes that it has been daimed that, in some colloidal Systems, ordinaiy tnrbnlence comes in at an abnormally high Reynolds’ nnmber.

Reiner suggests that, in the case of deformable molecules, such as those of rubher, the molectile is extended to a degree which depends on its orientation with respect to the direction of flow. Since the molecule is rotating, this implies an oscillation which dissipates energy through the continnous phase,