Recipes, which originated at a time when empiricism ruled in chemistry, have been omitted, since they would only detract from the clearness of the matter. As far as it is possible I have avoided the “recipe fetish,” and have endeavoured to make clear to the reader the chemical processes to which regard must be had in the manufacture of the different pigments. Since the appearance of the first edition there have been many valuable innovations in the mineral colour industry, to which regard has been given in preparing this second edition in so far as they possess a really practical value. A critical examination of proposals and formulæ, which are found in large numbers in the journals, has been avoided, since I wished to keep for my book that character of a reliable text-book and book of reference which was ascribed to it in the form of its first edition. DR. JOSEF BERSCH. TRANSLATOR’S PREFACE. If excuse be needed for presenting a translation of Dr. Bersch’s book at so long an interval after the publication of the original (1893), it must be sought in the paucity of the English literature on the subject. It is hoped that the practical nature of the work will make it acceptable to the English reader. The subject-matter of the original has been preserved in the translation without alteration or addition, with the exception of an unimportant change in the order of arrangement. The metric system of weights and measures has been used throughout; for the convenience of those who are not familiar with this system, directions are given in an appendix for converting into English weights and measures. The section on paint grinding (Chapter LXIX.) is perhaps somewhat incomplete; for a more detailed and modern account of this branch of the subject the reader is referred to _Practical Paint Grinding_, by Mr. J. Cruickshank Smith, B. Sc., shortly to be issued by the same publishers. A. C. WRIGHT. HULL, _January, 1901_. TABLE OF CONTENTS. PAGE CHAPTER I. INTRODUCTION 1 CHAPTER II. THE PHYSICO-CHEMICAL BEHAVIOUR OF PIGMENTS 8 CHAPTER III. RAW MATERIALS EMPLOYED IN THE MANUFACTURE OF PIGMENTS 14 CHAPTER IV. ASSISTANT MATERIALS 16 Water—Chlorine—Ammonia—The Hydrometer—Sal Ammoniac or Ammonium Chloride—Ammonium Sulphide. Acids.—Hydrochloric Acid—Sulphuretted Hydrogen —Sulphuric Acid: Oil of Vitriol, Nordhausen Sulphuric Acid—Nitric Acid—_Aqua Regia_ —Carbon—Carbonic Acid Gas. Organic Acids.—Acetic Acid—Oxalic Acid—Tartaric Acid.