As the present Work contains the substance of these instructions, we may hope that our own industrious countrymen may not long be without a similar advantage. The value of this book has been universally recognised, and it has already been translated into several languages, although but recently into our own. A recent critic has said, with equal truth and eloquence,—“Rarely has a subject of inquiry, so fraught with beautiful and ready applications, been presented to us. To be familiar with this book is to possess a new sense. Every object in art and nature speaks a new and exciting language. Colour becomes music to the eye. We become impatient of any violent infringement of the principles of harmony, and seek every opportunity of putting our newly-acquired knowledge into practice. The minuteness of investigation, and the copiousness of illustration which characterize this volume are truly remarkable; the most untutored mind cannot fail to understand it, if steady attention be given. As a preparation for a course of scientific study, it is invaluable, for it is an excellent example of the Baconian method of investigation.” EXTRACTS FROM THE AUTHOR’S PREFACE. In seeking to discover the causes of the complaint made of the quality of certain colours prepared in the dyeing laboratory of the Gobelins, I was at once convinced, that, although the complaints concerning the instability of the light blues, greys, and browns, might be well founded, there were others, especially those of a want of vigour in the blacks employed for the shadows of blue and violet draperies, which were not so; for, having procured black-dyed wools from the most celebrated dye works in France and other countries, and having found that they were not superior to those of the Gobelins, I saw that the want of vigour alleged against the blacks was owing to the colours contiguous to them, and that the matter was involved in the phenomena of _the contrast of colours_. It was thus demonstrated to me that I had two absolutely distinct subjects to investigate, in order to fulfil my duties as Director of the Dye Works; the first being the contrast of colours, considered in the most general manner, both in relation to science and to its applications: the second—the chemistry of dyeing. These are the two centres around which have converged all my researches during the last ten years.