DIETRICH (Philippe Frédéric de). Description des gîtes de minerai, des forges et des salines des Pyrénées, suivie d'observations sur le fer mazé et sur les mines des Sards en Poitou. Paris et Strasbourg, Didot l'aîné, Cuchet et Treuttel, 1786. 2 parts in 1 volume in-4°, bound in full marbled basane, spine ribbed and decorated, title page, edges reddened (Binding of the period). First edition, illustrated with 6 hors-texte plates, including 4 fold-outs in colour, and 7 fold-out tables. This work forms the first volume of the "Description des gîtes de minerai et bouches à feu de la France", published in 6 parts in 3 volumes. Very important work: one of the 20 rarest books in the Pyrenees (Labarère). Spine skilfully restored (original ornamentation preserved), a small tear to the lower corner of the first cover (7 mm). One page (307) with a transverse tear over 3/4 of the leaf, without missing. Apart from these defects, a very fine copy, complete with all the plates, virtually free of foxing. Baron P.F. de Dietrich (1748-1793) was Secretary General of the Swiss and Grisons, a member of the Royal Academy of Sciences and the King's Commissioner for the visit of the Mines, the Bouches à Feu and the Forests of the Kingdom. He was the first constitutional mayor of Strasbourg. Although he embraced revolutionary ideas, he remained attached to the constitutional monarchy. It was at his home that Rouget de l'Isle composed and sang the Marseillaise for the first time. Having officially protested against the invasion of the Tuileries Palace on 21 June 1792, he had to take refuge in Basel. On his return to France, he was tried and acquitted by the Doubs court, but was then brought before a revolutionary court, which sentenced him to death. He was beheaded on 28 December 1793. Labarère 489 - Les vingt livres pyrénéistes les plus rares, N° XIV - Dendaletche 601.