As a “famous investigator into the most recondite mysteries of Nature”, Raimondo di Sangro achieved and created an unknown number of discoveries and inventions. Some of them were presented – in different phases of completion – to the scientific community of the time; others were donated to the Sovereign or shown to a number of especially chosen interlocutors, and still others were used in the Sansevero Chapel, and can still be admired (e.g. the mastic used for the cornice and the capitals of the columns, the incredible Floor Labyrinth, the polychrome inlay, the spectacular colours of the vault, the unusual inscription in relief on the Tomb of Raimondo di Sangro and the Anatomical Machines).
His fundamentally esoteric conception of knowledge meant that almost all the “secrets” of his inventions – as Giuseppe Maria Galanti wrote in 1792 – “either died with him, or lie unknown in some corner of his home”. The literary sources and archives give further information on the variety of his experiments. Here follow some of his inventions not yet mentioned or explored in depth in the texts published here.
In the field of the arts, he invented the so-called “colori oloidrici” which had – explains the Short note on what can be seen in the house of the Prince of Sansevero – “the beauty of colour proper to the miniature, but […] the strength of oils”. This technique could be used on any material, unlike the normal miniature, which could only be applied to ivory, parchment, paper or other perishable materials. He was able to colour marble so that the colours penetrated “from layer to layer” and did not remain only on the surface. He made a number of artificial marbles, which he put on show in his palace. Here were also displayed two pictures made from “wools of various colours”, which created special optical effects and were characterised by mezzotints so delicate as to “rival any other oil painting”.
He did various experiments in manufacturing, in chemistry, mechanics and in other areas of research. He produced an above average and differently manufactured porcelain, whose formula was asked for by Ferdinando IV of Vincenzo di Sangro, son of Raimondo, soon after the death of his father. Back in 1748, he had made two different types of completely impermeable cloth. A riding coat sewn with one of these fabrics was given to King Charles by the Prince, and he used it during the winter hunting season. The following year, “he produced the most perfect painted silk cloth which the French call Pekin”. He built an automatic canteen, which served diners with all kinds of food without the need for waiters.
Another example. He invented “his own paper for artillery cartridges, which does not catch fire, nor does it spark, but immediately turns to carbon”. He invented wood and coal which did not produce ash upon combustion. He obtained artificial blood by treating chewed food and dung. He desalinated sea water. This is how the Short note ended: “the Prince made a large number of other fine discoveries, some of which seemed beyond the Natural order”.