Colloids and the Ultramicroscope available in Paperback
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- Zsigmondy Press
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CHAPTER II CLASSIFICATION OF HYDROSOLS ACCORDING TO TWO DIFFERENT POINTS OF VIEW l One of the most important tasks of a nascent science appears to me to be the arrangement of the available facts upon one single basis. If only an imperfect attempt in this direction can be made, it is because the point of view is so new, and the facts are so incompletely known. I consider it of importance, however, to direct the attention of investigators to this subject. Just as geologists distinguish, according to the size of their constituent particles, between boulders, rubble, pebbles, gravel, sand, and dust, so too in dealing with more finely subdivided bodies, a classification based on the size of the particles will be of corresponding value.2Pieces of like size have certain properties in common; for instance, sand and dust are carried by the wind, while cobble-stones and pebbles are unmoved; it makes no difference of what material the sand, dust, or pebbles consist. Sand will pass through a 10 mm. mesh sieve, but cobblestones and pebbles will not. 1 The best classification of colloids yet suggested is that of Hardy (Zeitschr. f. physik. Chem., Vol. XXXIII, p. 326). Recently Muller (Zeitschr. f. anorg. Chem., 1903, Vol. XXXVI, p. 340) suggested a classification with which I cannot agree, for reasons that may in part be gathered from the following chapters. Nevertheless I fully agree with Muller that colloidal chemistry must establish a classification of hydrosols. Independently of Hardy, the changes of condition of colloids have been divided by Wolfgang Pauli (Arch. f. d. ges. Phy- siologie, 1899, Vol. LXXVIII, p. 315), into those easily and those with difficulty reversible. A classificationof the various kinds of sand, pebbles, and dust, according to the size of their gra...