Much of the substance of the lectures which I have delivered before the Royal Academy since the year 1880 has been incorporated with the present manual, but it is necessary to state that some of the original material to be found in the following pages has been long before the artistic world, and has found its way into the books and essays of other writers. I say this, not for the purpose of making reclamations of priority, but in order to prevent myself from being charged with plagiarism. For instance, so long ago as 1859, I described, for the first time, some of the artistic uses of solid paraffin in a paper on the processes of painting, read before the Oxford Architectural Society; further details were given in a lecture to the Architectural Association in 1862. On many other matters connected with the chemistry of paints and painting, new investigations and studies were published by me between the years 1867 and 1872, particularly in notes and essays entitled 'Chemical Aids to Art,' and 'The Chemistry of the Fine Arts.' But my statements and results, whether contained in the above publications or in my Academy lectures, have not been, in all instances, referred to their source, or reproduced with accuracy, while some have been overlooked or forgotten.
In preparing the present volume I have made considerable use of several of the works named in my Bibliographical Notes; I have consulted also the standard chemical dictionaries of Watts and of Wurtz, the treatise by Roscoe and Schorlemmer, besides many special papers
