Colloids in biology and medicine / by Prof. H. Bechhold ... Authorized translation from the second German edition, with notes and emendations by Jesse G. M. Bullowa ... 54 illustrations.

  • Heinrich Bechhold
Date:
1919
Catalogue details

Licence: Public Domain Mark

Credit: Colloids in biology and medicine / by Prof. H. Bechhold ... Authorized translation from the second German edition, with notes and emendations by Jesse G. M. Bullowa ... 54 illustrations. Source: Wellcome Collection.

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    CHAPTER I. WHAT ARE COLLOIDS? In spite of the fact that they have a much wider distribution than crystalloids, it is only a little over fifty years that colloids have been scientifically studied. Plants and animals and all the things we manu¬ facture from them, such as our clothing and the greater part of our household goods, are colloids. In the year 1861, Thomas Graham,* 1 an Englishman, called attention to the fact that there were substances which, when in solution, diffused through parchment membranes (dia¬ lysed). These he called crystalloids because the soluble crystallizable substances (e.g., sugar and salt) possess this property to a marked de¬ gree. Substances which were held back by parchment membranes he called colloids, “glue-like/’ because glue was the most character¬ istic of this group. Every discoverer of a new fundamental principle is easily led into exaggerations; it so happened with Graham who opposed crystalloids to colloids as “two distinct worlds of matter, ’ though we know now that all sorts of transition stages exist. In succeeding years very few investigators concerned themselves with colloids. The very fruitful development of organic chemistry occupied the attention of investigators, who neglected, as less important, a field which promised fewer immediate results. Only in the beginning of the new century was there a revival of interest in colloid chemistry. We .shall not follow the historic development further, but shall give a description of colloids in accordance with the present state of the science. It must be noted at the outset that, even to-day, the behavior of a dissolved substance towards a partitioning membrane, that is, inability to diffuse through it, is the chief characteristic of a dissolved colloid. Many colloids form with liquids, especially with water, a more or less fluid solution. [The term dispersion is preferred by Arthur W. Thomas in a recent discussion on Nomenclature. Science, N. S., Vol. XLVII, No. 1201, p. 10. Tr.] This solution is called a sol (from 1 An * after an author’s name refers to the reference in the index of authors. 3
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