They started using .925 earlier than 1919. What year was the coin you found I couldn't make out the date. 1919? I found this coin two years ago it was a 1915. I haven't found any US coin older than that. Although I have found a few older foreign coins but they weren't silver. Nice find you have there. Congrats.
Frank, mine is 1919. It has an attractive toning of high content silver. Your dime is in much better condition. The other old silver foreign coin I found is a 1913 india one rupee, which has 91.7% silver.