The structure of thin films.—Part V

Abstract

The results recorded in this paper are an extension, with fresh substances, of those described in Parts II and III of this series of papers. No fresh principles have been introduced, and the experimental method and mode of recording results have been as before. The results are confirmatory of the theories developed in these papers. The α -Bromo Acids, CH 3 ( CH 2 ) n CHBr COOH . A series of six of these was available from the valuable collection of Dr. Le Sueur, and gave a very interesting series of films. In the condensed films, the most obvious point is the increase in the area of the heads of the molecules caused by the bromine atom; the next, a rather less agreeable one, is the property that these heads have of packing into several different arrangements of somewhat different areas, according to circumstances. These have not yet been fully worked out, but at least three distinct packings have been recognised. Possibly a greater number exist. As with the unsubstituted acids the packing is closer on water than on HCl. The phenomena on distilled water are complicated by some differences depending on the length of time the water has been in the trough, similar to those found with the simple fatty acids (Part II, p. 466).