In addition, moreover, most of the leading makers, anticipating some form of restriction on this admixture, had been for some time previously seeking substitute colour formulæ, and although it may be said by some that colours were obtained by the use of chlorate and sulphur which have not been equalled by subsequent formulæ, yet most have not only been equalled but improved upon, and the small minority remaining are an insignificant price to pay for the security and safety gained in manufacture. Between the publication of Chertier’s book in 1856 (nearly thirty years later than his first pamphlet) and the close of the century, several works on pyrotechny made their appearance, several by Frenchmen: Tessier, 1859, “Traité Pratique des Feux colorés,” two works in the Roret encyclopædia series, “Pyrotechnie Civile” and “Pyrotechnie Militaire,” published 1865, and in 1882, “Traité pratique des Feux d’Artifice,” by Denisse. The English works of any value during this period were: “Pyrotechny,” by Practicus, Brown’s “Practical Firework Making,” and “The Pyrotechnist’s Treasury,” by Kentish, 1878. Hutstein and Websky’s “Art of Firework Making,” published at Leipzig in 1878, a book published under the same title by Oscar Frey about 1885, and “A Theoretical and Practical Treatise of Civil Pyrotechny,” by Antoni, published at Trieste in 1893, together with some works on military pyrotechny published both in Europe and the United States, complete the list. Some of the military works are of considerable value, but are chiefly directed to the study of rockets and signals; some, however, are in the same category as “The Artillerist’s Manual and British Soldier’s Compendium,” by Captain F. A. Griffiths, R.A., published in 1852. The section dealing with fireworks in this work might almost be taken as an attempt to be humorous on the subject. The author quotes in all seriousness formulæ dating from the days of Bate and Babington, and knows so little of his subject that he gives instructions for making the same firework under different names under the impression that they are distinct units, the information being obviously pillaged from earlier writers. Generally a study of the above-mentioned works indicates that the tendency in pyrotechnic compositions has been in the direction of simplification. During the eighteenth century the useless ingredients had been in a great measure eliminated. The “burnables” had been reduced from a long list of alchemistic survivals to a mere half-dozen or so. Gums had been reduced practically to shellac alone (the use of gum arabic as an adhesive is quite distinct), carbons to lampblack and charcoal, and these with sulphur and sulphides of antimony and arsenic practically completed the list. Of the metals the use of pure zinc, copper, and brass has been discontinued, and the two almost revolutionary additions of magnesium and aluminium made, the former about 1865 and the latter in 1894.