I was glancing through a history of Laflin & Rand on Cast Pics, and saw that L&R had bought a powder mill in WI. Intrigued, I rooted about, and found a short write-up
http://genealogytrails.com/wis/grant...atteville3.htm
"After some negotiation, the property formerly known as “Griffith’s saw-mill,” on the Little Platte, about one and a half miles northwest of the present city, was purchased as a site, upon which buildings were erected, and the mill fairly put in operation during the summer of 1849."
Wow, they had a few corking good explosions.... I can't prove it, but I would expect that the powder was for blasting in the mines, not for shooting.
Platteville (Platte refers to the lead mines) is where the Wisconsin School of Mining is. Now part of the University of Wisconsin - Platteville.