Hubert T. S. Britton, A. F. Kitching, William Clayton, John Webster, L. Archbutt
1922 The Analyst  
Unless a student of chemistry has a good working knowledge oi the physicochemical principles underlying reactions, there is every likelihood that to him qualitative analysis will be more or less an unintelligent application of the analytical processes given in text-books. Such a training, besides being of doubtful value from an educational point of view, is scarcely conducive to the making of a good analyst; it being vital that he should understand as much as possible each process he employs to
more » ... ocess he employs to enable him to carry it out most efficiently. Attaching due importance to the value in qualitative analysis of these physico-chemical conceptions, Professor Hall departed somewhat from the text of Treadwell in preparing the previous edition, and, in addition to incorporating an account of these theories, rendered the work more comprehensive by revising the whole text in accordance with them. In the preface of the present edition he states that the annual sales of the book in its revised form have been more than doubled-a point 'which speaks for itself. The scope of the volume is essentially the same as that of the former edition. The work has, however, been brought up-to-date, apparently by comparison with the latest edition of Fresenius' Qualitative Analysis, and, moreover, several useful alternative separation tables have been added. These tables have been taken from the 1919 edition of Noyes' Qualitative Chemical Analysis, and have been carefully investigated by A. A. Noyes and his collaborators. The student thus finds himself confronted with the choice of several methods, but with very little information relating to their peculiar merits. I t is stated, on page 199, that "one scheme is best under certain conditions, and another scheme under different conditions." This statement is substantiated by reference to such phenomena as the carrying down of zinc and magnesium by chromium when precipitated a s hydroxide by the addition of excess of ammonium hydroxide in presence of ammonium chloride. To a large extent, the success of an analyst depends upon how far he overcomes difficulties of this nature, yet the instance quoted is the only attention paid to this important problem of occlusion by gelatinous precipitates ; no reference having been made to it in Part I. on " General Principles." Reference could well have been made to the recent investigation by Yasui (Mem. CoZZ. Sci., Kyoto, 1919, 4 (2), 65-67) on the attempted separation of the hydroxide of zinc from that of chromium, in which he found that very considerable amounts of zinc were retained, even after three treatments of the precipitate of chromium hydroxide, It seems more desirable that one scheme of analysis,
doi:10.1039/an9224700186 fatcat:log4sp5ghbfhtbj3ndm5rdc2ka