My purpose in writing this book is to describe my own experiences, from my graduate student days in the 1950s to the present (2001). when I came upon phenomena or facts that did not support the prevailing ideas and theories, or even contradicted them. In some instances, the encounters began with nothing more than the naive questions I posed as a graduate student to my professors regarding a well-established fact: others were the result of questions my graduate students asked me. Essentially, this is an account of my personal encounters with some of the ideas and theories that once prevailed but were later eliminated in the history of auroral science. I believe that young researchers becoming successful as scientists depends on how they deal with new phenomena or facts that do not fit established theories. One cannot be a researcher unless he/she can encounter such a problem. This is because such ;ui encounter is the very first step for new progress. When encountering such problems, some may put the discordant facts on the shelf or sweep them under the rug. so to speak, at least for a while. Others may try hard to find a way to make new facts fit into prevailing ideas by modifying or improving them. Yet others may try to establish a new idea, scheme, or theory by adapting their findings and those of others, but abandoning the prevailing interpretation of the phenomena or facts. It has been my experience that it is the people in this last group who produce epoch-making progress in science. The choice of what to do when facing this situation is not easy and depends on many factors, lirst of all. researchers have to know where they stand at that point in the history of their scientific discipline. It is therefore crucial to have a deep historical knowledge of the background of a prevailing idea or the established interpretation of a phenomenon. To choose a course of action without knowing the background would be like starting to run in the dark without a sense of direction or of the surroundings. Unfortunately. I see too many young scientists doing just that, particularly those who believe that technological advance is everything. Often, a mentor provides the history, not necessarily in a classroom setting, but through daily interactions. I was fortunate to have a very good mentor. Sydney Chapman, who guided me during my early days.

This book describes extraction of nickel, cobalt and platinum-group metals. The starting point is ore-in-place and the finishing point is high-purity metals and chemicals.
We have combined the description of these metals in one book because they very often occur together, are extracted together and have similar properties.
The objectives of the book are to:

(a) describe how these metals occur and are extracted;
(b) explain why these extraction processes have been chosen;
(c) indicate how the processes can be operated most efficiently, with minimal impact on the environment; and,
(d) suggest future improvements.

The series of articles on Facies Models in Geoscience Canada was initiated by editor Gerard V. Middleton, partly in response to a suggestion from Erich Dimroth that "brief, well-written, concise articles, outlining the techniques of rock interpretation, and the concepts and criteria for regional evaluation would be an enormous help to the general purpose field geologist”. Each author was asked to prepare a review that covered the basic ideas, without unnecessary jargon, in terms that the student or "general purpose field geologist” could understand. Most of the illustrations in the articles have been prepared with this objective in mind.

Facies models are encapsulated summaries of sedimentation in a depositional environment. Since the initial formulation of this concept (Walker, 1979a), facies models have become the cornerstone of modern sedimentology, and will continue to be a vital starting point for whatever new areas of research develop in the future.