Deciphering Two Letters of the Prince of Castelcicala on the Commercial Treaties of 1816 and 1817

Two letters of Fabrizio Ruffo, prince of Castelcicala, kept in the Archivio di Stato di Napoli and photographed for the DECODE database as records R9586 and R9588, are written in a numerical code that had not been read. I show that it is a one-part code, in which the numbers run in the alphabetical order of the syllables and words they stand for, and I give a key and a reading of both letters. Of the 969 code groups, 955 now have a value and six are nulls. The letters were sent from Paris to the Neapolitan envoy at Madrid in 1817, one in February and one in the summer, and they deal with the abolition of the old commercial privileges of Britain, France and Spain in the Kingdom of the Two Sicilies. Files: the paper (PDF); castelcicala-transcription.txt, a transcription of both letters made from the DECODE photographs, with the uncertain digits listed; castelcicala-key.tsv, the reconstructed key; castelcicala-decoding.txt, a line-by-line decoding. No images of the documents are included.