In attempting to classify the compositions in Frézier’s book one is staggered by the grotesque character of many of them and by the extraordinary variations in the proportion of their ingredients, even amongst compositions designed for a similar effect.
Presumably with the intention of impressing his readers with the wonders of the science, he added ingredient after ingredient, which, if they did actually no harm to the composition, certainly in no degree assisted its functioning.
In what he calls a simple star there are eleven ingredients, of which, in fact, four only are essential.
Further, beyond the multiplication of unnecessary ingredients in individual compositions, there is often their incompatibility and innate unsuitability for the purpose. Such components as ink, onion juice, and the drainings of a dung-heap suggest so strangely the formulæ of the alchemists that one almost expects to come across “the hair of a Barbary ape,” or similar absurdity.
Ruggieri, who may be considered as the last of the old school, is the first author to deal with the subject in such a way as to convince the professional reader of the practical knowledge of the subject.
His additions to the list of ingredients are not many, but they are genuine. He is the first writer to make use of metals or their salts in the production of colour; he includes among his chemicals metallic copper and zinc, also the acetate and sulphate of copper, and chloride of ammonium. The notable advance in his colour compositions, besides the use of metal salts for that purpose, is the introduction of a chloride, which has the effect of improving the colour by assisting in the volatilisation of the metal. For this purpose he used sal-ammoniac, the use of which has now been almost discontinued on account of its hygroscopic nature, notwithstanding that its base of ammonium is very useful in compositions containing copper. Its place is now generally taken by calomel; in such compositions chloride of sodium had been used for many years, but not as a chlorine carried. Ruggieri appears to have been the first to produce colour on anything approaching modern lines, and although he did not progress greatly, what he did achieve was undoubtedly a marked advance in the art.
His account of the invention of this composition is interesting. He says that he was told by a returned traveller from Russia of a set piece representing a palm tree, “the colour of which rivalled nature.” This piece he set out to imitate, which he did, at any rate to his own satisfaction. The result he obtained would undoubtedly give a good colour, if the method of firing was very clumsy. He remarks that he does not know if his method was as that adopted in Russia, and later of the “merit if not of discovering a new fire at least to have imitated or rather to have rediscovered it.” It appears, therefore, that there may be some doubt as to the originality or priority of Ruggieri’s achievement in this direction, but he must be credited at least with independently arriving at the result. Indeed it is more than probable that the piece seen in Russia was quite different, a transparency or illumination, either imported or copied from the work of Eastern pyrotechnists, and that the whole credit of introducing colour into the art belongs to Ruggieri and to him only.
He mentions that he puts it on record with the object of “thus preventing writers from attributing it to the Chinese, the Medes, or Arabs, as is the custom in Europe, and above all in France, where more than elsewhere there is a mania for enriching foreigners with our merits and to rob ourselves of the birthrights of genius.”