The county of Williams is unique, because they had many gaps in recording the Naturalization records in the county. Records are stored in two separate locations. They are the Common Pleas Court and the archives in Bowling Green.
The records at the county level are located at the Common Please court in Bryan. Dates are sporadic on their coverage. Here are the dates from the archives and they will be the same at the courthouse. 1836-1839, 1842, 1860-1864, 1873-1906 and 1922-1929. Be sure to check ahead prior to looking for your records to make sure your relative falls within these dates. Another place to check would be the neighboring counties and Toledo. They have no letters of intent.
Searching for these types of records in Williams Co will be a challenge. Have a great day.