There are a number of literary references to condoms by authors such as the Marquis de Sade, Casanova and James Boswell, and condoms - which in those days were used more than once - can be seen in the backgrounds of contemporary paintings, hanging up on hooks to dry, ready for the next excursion.
For the curious, here's how to make a sheep-gut condom, according to a publication in 1824. Soak a sheep's intestine caeca in water for a number of hours, then turn inside out, and macerate them again in weak alkaline, changed every 12 hours. Scrape them carefully to remove the mucous membrane, leaving the peritoneal and muscular coats, and expose them to the vapour of burning brimstone. Then wash them in soap and water, inflate them, dry them and cut to a length of seven to eight inches. Finally, border the open end with a ribbon to tie round the base of the penis, and before use soak the condom in water to make it supple.
http://www.bbc.co.uk/dna/h2g2/A375446