Publisher's Synopsis
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1920 edition. Excerpt: ... jacobus henricus van'T hoff ou have two substances: they both have the same atoms, the same number of atoms, in the same proportion by weight. So far as you can make out, they both have the same structural formula. Yet they show decided differences in properties. They have different crystalline structures and different optical properties, for example. What are we to make of this? Such was Pasteur's problem with his famous tartaric acids. Such was Wislicenus's difficulty with his lactic acids. Structural formulas, as written on paper--in two dimensions therefore--failed utterly to show any differences in these compounds. Now, of course, it did not require any very keen insight on the part of Pasteur, Wislicenus, and others, to realise that real molecules occupy not two but three dimensions, and that at best, paper formulas were a useful, but not a real mode of representation. Were the differences in these compounds to be ascribed to differences in the internal structure of the molecule, and if so, was there any possible method of showing this? The twenty-two-year-old van't Hoff, already dissatisfied with these paper pictures, and pondering over the more profound question as to the possible way in which the atoms themselves are held together in the molecule, introduced the conception of molecular structure based on the tetrahedron, and with it gave an impetus to the development of organic chemistry which is felt with added force from day to day. One need but mention the carbohydrates and proteins to realise how much we owe the knowledge of the chemistry of these substances to van't Hoff's new branch of the science--stereochemistry.1 But stereochemistry was simply a branch development, as it were, of the main inquiry which van't Hoff set...
