Information I have recently come across (see my last post) gives me slightly more information on Jean Gaspard Weiss and his life upon his return to Mulhouse, after achieving great fame and wealth in England through his flute playing.
From 1347 to 1798 the city of Mulhouse was part of the city-state of the Republic of Mulhouse, independent from France and allied with Switzerland until the Grand Council of the Republic of Mulhouse voted to join the French Republic. During its time of independence the city of Mulhouse was a protestant (Calvinist) enclave which developed into a solid industrial city, based on the manufacture of Indian cottons, which were prohibited from importation, manufacture and use in France until 1759, despite and because of the enormous popularity of Indian cottons. So because they were prohibited but highly sought-after in neighbouring France, Mulhouse was well placed to manufacture them.
When Jean-Gaspard Weiss returned home to Mulhouse in 1783 he sat on the Grand Council of the Republic of Mulhouse, and later on the municipal council (presumably after Mulhouse joined France). Mulhouse's social and political elite had the Dollfus, Koechlin and Hofer families at the top. Of the three men who founded Mulhouse's first textile printing factory, producing Indian cottons, two were from these three families: Samuel Koechlin (who was the son-in-law of the one of the most distinguished mayors - bürgermeisters - of the Grand Council, Jean Hofer) and Jean-Henri Dollfus (who later became Bürgermeister himself) - this textile printing business led to today's internationally known embroidery thread company DMC (Dollfus-Mieg and Compagnie). When Jean Gaspard Weiss started his own textile printing factory he worked in partnership with Jean-Jacques Dollfus, Nicolas Dollfus and his own son Jean-Georges Weiss (which seems a little strange to me because the information I have on Jean-Georges says he was born in 1785...). However, it was clearly important to be well-connected, particularly with the Dollfus family, but despite this the business venture only met with marginal success.
It is interesting that Jean Gaspard Weiss was involved in the politics of Mulhouse. From March 9 to July 25 in 1843 a Jean Georges Weiss was interim Bürgermeister of Mulhouse - this may have been Jean Georges Weiss, son of Jean Gaspard Weiss. Certainly the son Jean Georges was alive in 1843 - he was born 1785, died 1874. Jean Georges Weiss also gets another mention in the history of Mulhouse - in 1805 he was was in command of the reorganisation of the "old body of gunners" (I think there may be something lost in the translation here... Réorganisation de l'ancien corps des canonniers, sous le commandement de Jean-Georges Weiss), and was in charge of the town fire engines, of which there were four. Of course, it is possible that this was a different Jean-Georges Weiss - Weiss was apparently a very common name in Mulhouse.