I get some off white powder from St.Louis from time to time and it's always in caps and it's always really good shit, always had a normal lasting high for me, If the shit you get is white and you rush good and then it goes away after 2 hours that sounds like Fentanyl laced shit or Fentanly cut with dope , cause Fentanyl shots will give you a hella rush and the high lasts about 2 hours, I don't want to say it is Fentanyl laced though, just sounds kinda like a Fentanyl buzz, but it is over after 2 hours, but I dunno, it's likely just got a bit too much cut maybe, dunno..The white shit I got every time from St.Louis was always not cut very much it seemed to be pretty fire shit, and lasted as long as any other good dope did..guess it comes down to different dealers and shit..