Theoretical organic chemistry / by Julius B. Cohen.

  • Cohen, Julius B. (Julius Berend), 1859-1935.
Date:
1912
Catalogue details

Licence: Public Domain Mark

Credit: Theoretical organic chemistry / by Julius B. Cohen. Source: Wellcome Collection.

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    in the majority of cases, to occupy not more than a few minutes. For a reaction done in a test-tube is just as effective didactic¬ ally as a more sensational experiment performed on a larger scale, and involving a greater expenditure of time. The book, including all these experiments, represents my own course of about sixty lectures. The production and uses of common materials, which come under our daily observation, are frequently relegated in some text-books of organic chemistry to a background of small print ; in others they are entirely omitted. The reason for this is not clear, unless it arises from our present ignorance of the structural formulas and relations of some of these compounds, and therefore from their lack of theoretical significance. Whatever may be the cause, substances like lanoline, linseed oil, gelatine, the tannins, turpentine, &c., are usually treated in this stepmotherly fashion, and industrial processes, like tanning and sugar-refining, the manufacture of varnishes, petroleum, glycerine, soap, starch, &c.,„ are dismissed with no more than an honourable mention. I make no shadow of a claim to having accomplished the task of producing an ideal text-book. It is beset with many diffi¬ culties. One difficulty arises from the very completeness of the subject, for, to pursue the former metaphor, organic chemistry forms not only a chain, but an endless chain of facts. At the beginning, one is confronted with the difficulty that the simplest organic compound involves a knowledge of others of greater complexity. Certain assumptions have, in consequence, to be made, which upset at once the natural development of theories, and the gradual elaboration of the principles of structure, causing the text to bristle with cross references, which cannot be avoided. No attempt has been made to give anything like a complete set of methods for preparing even the more important of the sub¬ stances described ; on the contrary, the number has been care¬ fully restricted to those which have a theoretical importance, or practical value. For example, the numerous methods which are generally introduced in describing the preparation of marsh-gas are greatly curtailed, and the complex reactions involving the use of zinc and magnesium alkyl compounds are grouped together in a later portion of the book, where the close analogy, which they